Bosch Model EFEP 515 Fuel Injection Pump Test Bench

This post is a plea for help.

I have this Bosch injection pump test bench, Model EFEP 515:

dscf2945It came with precious little information.  I do have the “Operating Instructions” manual, which is 40 pages long and written in four languages.  It contains roughly 10 pages of written English instructions that give the basic information necessary to operate the test bench.

What I don’t have is anything that tells me how to actually hook up, test, and calibrate an injection pump.  I feel that there is probably no way that I would ever be able to figure out on my own what I need to know to use this machine.  I need a knowledgeable person to give me a few lessons.  I think a retiree who has actually used these machines is just what I need.

I would be using this machine, probably exclusively, to test and calibrate Bosch “VE” injection pumps as used on the Volvo D24 Diesel engine, or the similar Volkswagen Rabbit Diesel engine.  See:

If I were to rebuild and test a half-dozen such pumps in a year, I would be surprised, so I’m really not going to be serious competition to anyone, or pose a threat to their livelihood.  I’m a hobbyist, nothing more.

So, I’ve posted this in the hope that someone who knows how to test and calibrate Bosch “VE” injection pumps will see it, or perhaps someone who knows such a person will see it.  If they’re willing to show me how to test Bosch “VE” injection pumps, I’d be willing to pay them a reasonable fee for their trouble.  Or, perhaps, they’d like to have an all expense paid “vacation” in the great State of Maine.

The test bench came with this additional equipment cabinet:

dscf2946As best I’ve been able to determine, this equipment is used to maintain the test fuel at proper operating temperature for testing the injection pumps, probably in a high-volume production environment.  I believe I will not be needing to use this equipment.  So, I suspect I will be looking for someone who can use it.

If you know anyone who can help me, please ask him to contact:

Tom Bryant
32 JBS Way
Wiscasset, Maine 04578



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Volvo D24 & D24T Diesel Power Steering Pump Bracket

I now have available reproduction Power Steering Pump Brackets for Volvo D24 and D24T engines as used in the North American Market for the Volvo 240 and 700-series from 1979 through 1986.  These brackets replace Volvo Part Number 1328517-7, used on the 240-series, and Part Number 1257805-0, used on the 700-series.

After discussing the two applications with members of the D24 mailing list, a consensus was reached that, since the cost of reproducing these brackets was high, and since the D24 (240-series) bracket could be used on either engine, whereas the D24T (700-series) bracket cannot easily be used on the Volvo 240-series because of interference with the top radiator hose, we would reproduce only the D24-type Power Steering bracket.

These D24 Power Steering Brackets are applicable to Volvo 240, 244, 245, 260, 740, 744, 745, 760, 764, 765, 940, 944, and 945 vehicles with D24 or D24T engines.

Here’s a photo of one of my finished D24-type power steering brackets:

Applicable to Volvo 240, 245, 260, 740, 744, 745, 760, 764, 765, 940, 944, and 945 vehicles with D24 and D24T engines

Volvo D24 Diesel Power Steering Pump Bracket
Fits D24 & D24T (Volvo 240, 740, 745, 760, 765, 940, and 945 vehicles)

The replacement Power Steering Pump Brackets are sand castings, whereas the original brackets are die castings.  Sand castings are much less expensive to make in the small quantities anticipated for these reproduction brackets.

To make these sand castings, I first engaged a pattern maker (Gage Pattern in Norway, Maine) to make a wooden pattern.  Here’s a photo of the pattern:

Applicable to Volvo 240, 245, 260, 740, 744, 745, 760, 764, 765, 940, 944, and 945 vehicles with D24 and D24T engines

Volvo D24 Diesel Power Steering Pump Bracket
Sand Casting Pattern and Mold

The pattern is painted gray and is shown in its place in the black casting form.  I will explain the casting process as best I can, based on my conversations with Auburn Stove Foundry, New Gloucester, Maine,  but I may not have all the details quite correct, so if anyone knows more about the sand casting process than I do, please set me straight on the particulars.

To make a single casting, a steel form is placed around the black form and packed with sand.  Then the form is turned upside down, the black form is removed, leaving the gray pattern in place, and a release agent is applied to the resulting split line.

Next, another steel form is placed atop the pattern and risers are placed in the top half to carry molten metal into the mold.  The top half is then packed with sand, forming a two-piece sand mold.  The two halves of the mold are separated and the grey wooden pattern removed.  Then, the two halves of the mold are re-joined and molten aluminum is poured into the cavity.

As you can imagine, this is a time-consuming and costly process, but in small quantities, it’s far cheaper than developing the tooling for the die casting method.

Next is a photo comparing the wooden pattern with a raw aluminum casting:

Applicable to Volvo 240, 245, 260, 740, 744, 745, 760, 764, 765, 940, 944, and 945 vehicles with D24 and D24T engines

Volvo D24 Diesel Power Steering Pump Bracket
Raw casting on left. Wooden pattern on right.

The raw aluminum casting is on the left, and the wooden pattern is on the right.  Notice that the casting is a bit smaller than the pattern.  That’s due to shrinkage as the molten metal solidifies and cools.  The pattern is made larger than the final finished dimensions to compensate for the shrinkage.

Here’s a photo of four raw aluminum castings, showing what they look like from four different directions:

Applicable to Volvo 240, 245, 260, 740, 744, 745, 760, 764, 765, 940, 944, and 945 vehicles with D24 and D24T engines

Volvo D24 Diesel Power Steering Pump Bracket
Raw Castings, Four Views

The castings and an OEM D24-type Power Steering Bracket, as well as a D24T engine (for fitment) were all delivered to a machine shop (Maine Tool and Machine, LLC, Brunswick, Maine)  Using the OEM bracket and the D24T engine for guidance, the machine shop developed a shop drawing and built tooling (two special fixtures) for machining the reproduction brackets.

Next is a photo of a finished bracket resting atop the first of the two machining fixtures that the machine shop made:

Applicable to Volvo 240, 245, 260, 740, 744, 745, 760, 764, 765, 940, 944, and 945 vehicles with D24 and D24T engines

Volvo D24 Diesel Power Steering Pump Bracket
Finish Machined Bracket and Machining Fixture


The next photo shows this first fixture in use on the milling machine:

Applicable to Volvo 240, 245, 260, 740, 744, 745, 760, 764, 765, 940, 944, and 945 vehicles with D24 and D24T engines

Volvo D24 Diesel Power Steering Pump Bracket
Partially Machined Bracket and Machining Fixture
Mounted on CNC Milling Machine

Note the steel clamp at the left of the photo, holding the bracket down to the fixture.

Next is a photo of the second machining fixture:

Applicable to Volvo 240, 245, 260, 740, 744, 745, 760, 764, 765, 940, 944, and 945 vehicles having D24 and D24T engines

Volvo D24 Diesel Power Steering Pump Bracket
Machining Fixture


Next is a photo of the second fixture with a finished bracket attached:

Applicable to Volvo 240, 245, 260, 740, 744, 745, 760, 764, 765, 940, 944, and 945 vehicles with D24 and D24T engines

Volvo D24 Diesel Power Steering Pump Bracket
Finish Machined Bracket Mounted on Machining Fixture


And now a photo of the second fixture in use on the milling machine:

Applicable to Volvo 240, 245, 260, 740, 744, 745, 760, 764, 765, 940, 944, and 945 vehicles with D24 and D24T engines

Volvo D24 Diesel Power Steering Pump Bracket
Partially Machined Bracket Mounted on Fixture in CNC Milling Machine

Notice that the bosses for the rubber bushings have been surfaced to properly locate and orient the rubber bushings.

Next is a photo showing how the bosses are bored to accept the rubber bushings:

Applicable to Volvo 240, 245, 260, 740, 744, 745, 760, 764, 765, 940, 944, and 945 vehicles with D24 and D24T engines

Volvo D24 Diesel Power Steering Pump Bracket
Boring the Bushing Holes with a CNC Milling Machine

You’d never know it from the above photo, but the fixture is designed to hold the bracket such that it’s tilted forward at the top by a 1 degree angle.  That is to compensate for the flex of the rubber bushings when the V-belt is tightened so that the Power Steering Pump pulley will be properly aligned with the crankshaft harmonic balancer and fan pulleys.  The one degree angle was determined by careful measurements made on the OEM bracket that was used for guidance.

Next is a photo of three Power Steering Pump Brackets:

Applicable to Volvo 240, 245, 260, 740, 744, 745, 760, 764, 765, 940, 944, and 945 vehicles with D24 and D24T engines

Volvo D24 Diesel Power Steering Pump Brackets
Original Equipment D24 (Volvo 240) Bracket at Front
Reproduction Volvo D24 Bracket at Center
Original Equipment D24T (Volvo 700-Series) Bracket at Rear

In the front is an OEM D24-type bracket.  In the middle is one of my reproductions, and at the back is a brand-new, never used, D24T-type bracket.

Notice that the reproduction D24 bracket, when used in place of an OEM D24T bracket, will result in the Power Steering pump being attached a little lower on the engine, and therefore closer to to the Power Steering rack, such that the original power steering hoses will be a bit longer than they need to be and therefore a little more flexed (looser) than with the OEM bracket.  This should never be an issue.

Despite the change in pump location, the same V-belt is used on both D24 and D24T engines.  That is, the 240-series, and the 700-series Diesels both use the same power steering belt.

Although you can’t tell from the picture, the reproduction bracket is considerably thicker and wider than the OEM bracket, and it weighs about 775 grams, compared to about 573 grams for the OEM bracket.  The reproduction brackets were intentionally beefed up in critical areas to reduce the chance of breaking.  The foundry also claims that the sand casting alloy used (Tenzaloy, Alloy Number 713.1) is considerably stronger than the die casting alloy used in the OEM brackets.

Finally, we have a photo of the reproduction bracket installed on a D24T engine:

Applicable to Volvo 240, 245, 260, 740, 744, 745, 760, 764, 765, 940, 944, and 945 vehicles with D24 and D24T engines

Volvo D24 Diesel Power Steering Pump Bracket
Mounted with Pump on D24T Engine

Fitment is quite good, I believe, and alignment of the belt pulleys is just about as good as it could possibly get.

Development and production of these reproduction brackets was not cheap.  Altogether it cost me $7918.47 to produce 22 brackets, but one of those (the first prototype) didn’t come out right, and isn’t something that I can sell.  So, to break even, I have to get $377.07 for each of the 21 usable brackets; I’m going to round that up to $380.00 each.  So, if you’d like to order one of these brackets, that’s my price, plus shipping.  I’m sorry that the price is so high, but that’s what it has to be.  If these 21 brackets ever sell out, I can make more for less cost, but that will never happen unless I’m able to sell these ones first.

Tom Bryant
32 JBS Way
Wiscasset, ME 04578

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MGBrescuepilot Please Contact Me

Today (Sept 1, 2016) I received the following e-mail (below the row of xxx’s) from “” regarding a post that had just been made to this thread:,2566009,3345754#msg-3345754

For reasons that are unclear to me, the post has been removed, and the account of MGBrescuepilot (aka Jeff R) has been disabled.  I would like very much to contact Jeff R, but have no way to do so, since his account has been disabled.  So, if anyone out there knows who Jeff R is, could you please ask him to shoot me an e-mail at



Revision dated 9/3/2016:

MGBrescuepilot (aka Jeff R) has contacted me, and we have exchanged a few e-mails.  And no, I do not know his actual identity, or where he lives.  It seems that his post, copied below, to the forum is most probably what got him expelled from that forum, although the reasons are not clear, either to him or to me.  He has shared some speculations with me, and I tend to agree with his thoughts, but I guess I’ll not be sharing those speculations here.  I’ll just let you, the reader, make your own.



MGBrescuepilot wrote in Re: SU carburetor rebuild instructions


Did you know Tom Bryant put a link to the negative comments here, “in the interest of fairness” at the beginning of the H4 article?     Looks like he added the link shortly after this  discussion aired on MGE 2 years ago.  I found this discussion searching the MGE archives for info on rebuilding SU’s.  I was also specifically looking for info on the rebushing of throttle shaft.

In this other article on HS-6 rebuilding,  (about 6 paragraphs into it)  he updated in May 2016 that he has gotten a ultra-sonic cleaner to make the carbs he rebuilds pretty.  Before (2014)  he asked that the customers understand the carbs were not going to be cleaned, so if they were not already clean, to do it before sending them to him.  I guess he read the posts here about customers wanting clean,  and he thought about it, and decided it was a good idea to change.  Gotta give him points there. B)-  He discusses centering the jet pretty thoroughly, so if someone wants to roll their eyes about some sentence in that or any other of his discussions, I’m sure they can find something to poke at.  Overall his write-ups on SU’s, in comparison to other similar  write ups, is quite different and more in depth, so I would say better.  Dave Braun says he does not like the write up, and Hap thinks it is a waste of 5 minutes.  Hap does not say why it is a waste, but I imagine it is because he already has his own way of doing it right, and there was nothing for him to learn?  Fair enough, but what has Dave B got to say about what is wrong with the write ups?  I ask because I want to know what not to do, as well as what to do. Is there some bad info there, or just a different way of doing it?

As for the SU bashing, I have read his SU articles and must have missed it.  He gives a lot of tips and pointers, and as he says, he has got more SU’s to rebuild than he can handle, so the informative articles about how he does things are meant for people thinking of rebuilding their own carbs, including some of the best and detailed info on re-bushing with Delrin bushings, and even giving cutting tools sizes for the job.  Like using a 0.358 reamer and 0.366-0.371 delrin bushings, assuming the holes have not already been enlarged, which as he points out, must weaken the casting .  He talks in one about using Teflon O-rings to replace cork glands and bottom jet seal.  He shares info of .090 jet Teflon o-ring sizing, and shows an interesting technique to recess the jet holes to avoid damaging the Teflon.

Don’t know what his prices are now that he (ultrasonic) cleans the carbs, if different,  but price had been including new throttle shafts and delrin bushings with a (“the works’) rebuild of SU pairs for $220, using Teflon and other improved parts he discusses,  and new Joe Curto jets (he also shows you how to figure out if your old jets are any good).  I don’t recall seeing that anywhere else.  And who else uses the Delrin for shaft bushings?  I don’t know, I am asking, does anyone and how much?  Lifetime bushings sounds good to me.

So all I am saying is “a rather harsh review” I think, from MGE members back in 2014, with no real specific reasoning for the negative I can see, except the “cleaning” thing which was a good part of the discussion.  Has anyone use this guy, and can give a review of his work or delrin bushings in general?  thanks-

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Volvo 700/900-Series Fuel Filler Lid & Hinge

This post will be of interest to an extremely limited number of people, but I had a few requests for pictures, so figured I might as well.

In what follows “Before” refers to the condition of my Blue Lid before I “straightened” it.  “After” is after “straightening” that Blue Lid.

Over the past few years, I have heard of several people having problems with new replacement plastic hinges for Volvo 700 and 900 series fuel filler lids not fitting the old lids.  The consensus seemed to be that the problem was that the quality (especially dimensional control) of the new replacement hinges was sub-par.  That is, that the problem was with the hinges, not the lids.  My recent experience would indicate otherwise, that the problem is actually in the lids, not the hinges.

The hinge is Volvo Part Number 1380664-1, and I believe that part number has never been changed since the 700-series was first introduced in the early 1980s.  The lids, however have gone through several revisions, as follows:
1334649-9, supersedes to
3503391-9, supersedes to
3526601-4, supersedes to
9171105-1, supersedes to
All of these lids are clearly intended to fit onto the same hinge.

Here’s a photo of three lids and three hinges:

DSCF1980The Red Lid, at the top left, is from my 1985 745 TurboDiesel.  The hinge that was used to attach it to the car is to its right.  It’s unbroken and still fits the lid.

The Blue Lid, at lower left, is from my 1986 745 TurboDiesel.  It was attached to the car with the broken hinge shown at the center right.  When that hinge broke about a month ago, I purchased a brand-new hinge from Volvo, which did not fit the lid.

That brand-new, Genuine Volvo, hinge is shown at the lower right, just above a brand-new (Green) Lid, Volvo Part Number 30779269-7.   The Red and Blue lids are most likely Volvo P/N 3503391-9, but they could be the earlier P/N 1334649-9; I have no way of knowing which.

The new Genuine Volvo hinge, at the bottom, and the old, unbroken hinge at the top appear to be essentially identical in all their dimensions.  Each fits the Red and the Green lids perfectly.  But, neither fit the Blue Lid when I first tried them in that lid.  I found that quite surprising since the broken hinge (at the center) had fit the Blue Lid perfectly well until the pins broke off the hinge.  Those new hinges, however, fell right out of the lid.  Either the pins on the hinges were too short, or the distance between the “ears” on the lid was too great.

Notice, in the photo above, that the distance across the flats (at the base of the pins) is about 1.975″ for the new, Genuine Volvo, hinge at the bottom, but about 1.990″ for the broken hinge in the middle.  Initially, that difference indicated to me that Volvo had changed the design of its hinges, with new replacement hinges being shorter across the pins.  I believed that the pins on the new replacement hinge were too short, since the old (broken) hinge had fit just fine.  Eventually, however, I took that top hinge off my red car and compared it with the other two, and found that it matched the bottom (new, Genuine Volvo) hinge perfectly.

I now think that the broken hinge, from the blue car, had been larger than normal and that it quite possibly pushed apart the ears on the Blue Lid, such that it no longer fit a standard hinge.  Perhaps someone installed an aftermarket hinge on my blue car, but I don’t know; I’ve only owned the car for a couple of years, and I don’t know much about its history.

Subsequently, on recommendation from people who had used them, I purchased, via the Internet, a supply of Uro brand hinges and tried them in my Blue Lid.  They did not fit, either, although they were a smidgen (0.015″) longer across the pins, and so they came a bit closer to fitting.

The next photo shows a new, Genuine Volvo, hinge on the left, and a new Uro brand hinge on the right:

DSCF1981The above is actually an “After” photo, but I didn’t take a “Before” photo, so this will have to be good enough.  Had I taken a “Before” picture, the hinge on the left (whether Genuine Volvo, or Uro) would not have stayed put in the holes in the lid, but would have slipped right back out, similar to what is shown above.

But, this an “After” photo, and if one were to slip that left hinge into place, it would stay there.

The hinge on the right is Uro brand, and it fits my Red Lid perfectly.  The new Genuine Volvo hinge (at the left) also fits the Red Lid, although not quite as securely because the distance across the hinge pins is about 0.015″ shorter than across the Uro pins.  But it is exactly the same as the old Genuine Volvo hinge that had been holding that lid on my red car until I removed it a couple of weeks ago.

We’ll come back to the pin dimensions shortly, but first, here’s a shot of the Blue and Green lids:

DSCF1982This is a “Before” photo, but I was trying to show the outside dimensions of the ears, not the inside.   Those outsides differ by only about 0.012″, which is not very significant; the new Green Lid is narrower.

Next, another “Before” photo of those same two lids:

DSCF1983Here I was trying to show that the inside dimensions, at the root of the ears, was essentially the same.  Since the photo missed the right dial, you’ll just have to take my word for it that they are essentially the same.

I’m including this photo here because it shows fairly clearly the reinforcement buttresses that were added to the ears on the right lid, which appear to be intended to prevent spread of those ears, such as apparently happened to the Blue Lid on the left.

If you look carefully at the previous photo, you can also see those buttresses, but they’re not as obvious.

Next is an “After” shot of the three lids, comparing the distances between the insides of the “ears”.

DSCF1984The calipers are measuring the distance between the slots through which the pins get inserted.  That measurement is 2.148 for the Red Lid, 2.145 for the Blue Lid, and 2.180, for the Green Lid.  So, theoretically, the new Genuine Volvo hinge should fit the old Red and Blue lids a bit more securely than it fits the new Green Lid.

Again, the above is an “After” photo.  If I had a “Before” shot of the Blue Lid, that distance would be a bit larger.

Now, as promised, we come back to the hinges.  In the next photo, the brand new, Genuine Volvo, hinge is at the top, and the new Uro brand hinge is at the bottom:


The measurement across the pins of the Genuine Volvo hinge is 2.270″.  The Uro hinge measures 2.185″, a difference of 0.015″, so the Uro brand hinge should fit any of the lids a bit more securely, and it does.

So, how did I “straighten” the Blue Lid?  The next shot shows the fixture:

DSCF2010I simply put a C-clamp across the “ears” and pushed them inward, then I set the Blue Lid in a wooden cradle, and used a second C-clamp to bend the center of the lid, between the ears, outward to a more convex shape, as seen from the outside of the vehicle.

Then I put the Blue Lid in my wife’s oven at 200F for about 2-3 hours.  That was about a week ago, and the lid is still holding its “new” shape just fine.  It fits each of the hinges just fine, too.

So, which hinge do I recommend, Uro or Genuine Volvo?  I’m not sure.  The Uro brand hinges are less expensive, but a not a lot less.  And they do fit the Lids a bit more securely.  Assuming they’re made of the same plastic, they should each last equally long.  So, you be the judge.


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Volvo, Volkswagen, Audi Diesel Pierburg Vacuum Pump Rebuild

In Memoriam: JRC, Unity, Maine, December 27, 1949 – October 30, 2014.

This post describes, in general terms, how to rebuild a Pierburg vacuum pump as used on Volvo D24 and D24T engines from 1979 to 1986 in North America and through the 1996 model year in Europe.  The six-cylinder D24 and D24T engines were built by Volkswagen and were also used in the Volkswagen LT truck series.  A similar five-cylinder engine (the D20) also used the same Pierburg vacuum pump and was used in certain Volvo and Audi vehicles.  The four-cylinder Vokswagen Diesel engines of the same era did not use this vacuum pump.

The level of detail presented in this post will not be as great as in most of my earlier posts on other subjects because my intent here is to describe the problems and failure modes and to give a general idea of how to rebuild one of these vacuum pumps, but not to show all the specifics because the machining work involved is beyond the capabilities of most people.

Because I don’t have the necessary machine tools to do this work, I farmed the machine work out to a small local machine shop, which charged me $75.00 per pump for just the machine work.  It is primarily for that reason that I must get a fairly hefty price for these rebuilt vacuum pumps.  In addition to supplying the materials and paying for that machine work, I also had to disassemble and clean the pumps, then reassemble and test the pumps, so I also have a lot of labor invested in this project.

This vacuum pump comes in two basic varieties, as shown in the following photo:

DSCF1900The earlier type pump is shown on the left and the later type is on the right.  Only the earlier type was used on vehicles imported to North America from 1979 to 1986.  The later type is more difficult to rebuild; in fact, I’ve never rebuilt one of them, and I’m not sure that I would be able to if it should be needed.

I currently have a supply of 11 of the early style pump, all rebuilt, tested, and ready for sale at $120.00 each, exchange, plus shipping.  Although I will accept the later type of pump as a core, I prefer not to because they may prove to be impossible for me to rebuild, and I may decide that I will have to charge extra if someone wants to send me a later pump as a core.

I first rebuilt one of these pumps, by the methods described below, on March 30, 2003.  Since then I have rebuilt about 3 dozen of these pumps, and collectively, they have been used for hundreds and hundreds of thousands of miles without any significant problems being reported.  Some of these pumps have been used for well over 100,000 miles.  So, the repair methods and materials have been well tested and are “tried and true.”

The next photo shows how I usually disassemble one of these pumps for repair:

DSCF1901Note the Vise Grips on the back side.  That was necessary for this particular pump because the bolt that holds the piston in has a round head on it.  Some of the pumps use a bolt with a 15 mm hex head, which is a bit easier to deal with.

The next photo shows that bolt, partially removed, as well as the shaft seal:

DSCF1902The shaft seal consists of a plastic ring surrounded by an o-ring.  The seal is held in place by a steel cup-shaped piece that also serves as a base for the spring.  That steel part is not shown in the above photo, although the similar outer washer is partially visible at the top of the photo.

The next photo shows the same seal, but without the shaft:

DSCF1903This seal was in good condition, but many of them are not.  They frequently wear severely, causing the pump to not work well.

The next photo shows the same pump after removal of the seal:

DSCF1904Note the brass (or bronze) bushing that is still in place in the bore.  The plastic seal may be seen lying on the workbench, to the right of the pump.

In the next photo, the brass bushing has been removed:

DSCF1905The shaft (bolt) is lying to the right, with the bushing and o-ring on it, and with the plastic seal lying on the workbench, just above the shaft.  Note that the bore hole for the bolt is stepped so that there is room for the plastic seal and o-ring at the outer end.

The repair procedure involves enlarging the bore hole to accommodate a Delrin bushing, which replaces the brass bushing, as well as the plastic seal and o-ring, with a single component.

Most of the pumps that I’ve disassembled have failed right here at this bushing.  The bushing wore out, which in turn caused the plastic shaft seal to wear out, which resulted in leakage along the shaft and caused the pump to not draw a decent vacuum.

The next photo shows two shafts with their respective bushings, seals, and o-rings:

DSCF1907Notice that in the lower photo, the bushing is worn completely away in one area, as has the shaft seal.  In my experience, this is the most common failure mode for these Pierburg pumps.

Other failure modes are:

  1. Broken valves.  One such broken valve is shown at the lower right of the above photo.  Compare that valve with the one at the top right.  The first few pumps that I repaired had failed with broken valves, and I once thought that was the primary failure mode, but it is not; the shaft seal fails much more frequently.
  2. The rectangular o-rings that seal around the valves often get hard and don’t seal well.  Sometimes they get brittle and break.
  3. I suppose the seal around the large (2.95″, 75mm) piston could fail, but I’ve never seen one that did.

I don’t believe I’ve ever seen any other type of failure, other than caused by misuse or abuse.

In the next photo we see some of the internal components of the pump:

DSCF1908The large rubber seal comes in at least three varieties.  The two siamesed holes for check valves, at the left side of the photo, sometimes don’t have rubber rings all the way around them.  Sometimes one lacks the ring; sometimes the other also lacks the rubber ring.  The smaller of the two rings is used with a 5th check valve, which isn’t always present.  If the larger rubber ring is missing, then an o-ring is used instead.

Also shown in the above photo are:

  1. At top, two plastic spacers.  There is only one of these per pump; I’ve put two in the photo to provide two views of the same item.
  2. At the center, four check valves.  The one at the far right is broken.  This is the first broken check valve that I’ve seen in several years.
  3. At the bottom, two spacers.  Each pump has only one of these.  They come in two varieties; the one at the left includes that aforementioned 5th check valve; the one at the right lacks the check valve.  Each of these two types seems to work well; I’ve never seen any difference in performance between pumps that have the 5th check valve and those that lack it.

In the next photo are all the o-rings, seals, and bushings that I removed from the current batch of 12 vacuum pumps:

DSCF1910 There are twelve of the brass bushings, twelve plastic shaft seals, and 12 shaft seal o-rings. Notice that at the right of the row of 12 bushings are four that are worn out; the eight good bushings are shown end-on; the 4 bad ones are shown lying on their side.  Although it can’t be seen above, the four corresponding plastic shaft seals are also badly worn, and one of them (at far right) is broken, although that isn’t easily seen in the photo because the o-ring is touching the plastic seal at its 4 and 5 o’clock positions.

At the top of the photo are 40 of the rectangular o-rings used for the check valves.  Each pump has at least 3 of these.  Among these 12 pumps, four of them had the fourth check valve o-ring, the rest had the later type gasket, with the integral check valve seal, as described earlier.  We’ll come back to this again a bit later, near the end of this post.

Below we see three repaired vacuum pump bodies, ready for reassembly:

DSCF1939The vacuum pump body at the top has a reddish-brown bushing installed in it.  That bushing is made of Teflon-impregnated Delrin.  When I first started rebuilding these pumps almost 13 years ago, I made some bushings from plain Delrin (white) and some from Teflon-impregnated Delrin to see which would work better.  I could find no difference in performance or longevity, so now I use only the less expensive white Delrin.

The white bushing at the lower right is a new Delrin bushing, and the one at the lower left is a plain (white) Delrin bushing that was originally installed in a 1984 Volvo 760 in January of 2008, and has since been used for about 62500 miles.  The bushing shows a bit of discoloration, but has no detectable wear.  The pump was recently returned to me because the owner thought it had failed.  I reassembled the pump, tested it, and found that it worked just fine.  The owner has since admitted that he didn’t actually check his brake booster for problems before condemning the vacuum pump.  I have returned the pump to its owner; he will put it back in the car and see what happens.  I’m sure the pump is okay.  In fact, it tested the absolute best of any pump I’ve ever tested.  I measured it at 29 inches Hg.

Next we have the same three pumps, with the same bushings, and located in the same positions, but showing the other end of the bushings:

DSCF1940Because of the glare and reflections, the bushing at the top of the photo looks lighter than does the pure Delrin bushing at the lower left, but it is in fact the reddish brown Teflon-impregnated Delrin bushing.

Next is a photo comparing a pump that was just disassembled, at the left, with one that has been re-machined and has a Delrin bushing installed, at the right:

DSCF1945In the pump at the left, you can see the step in the shaft bore hole.  The larger diameter portion (toward the front) is empty space, which doesn’t help with the pump shaft sealing or pump performance.  The Delrin bushing, in the right pump, fills that space and contributes to the shaft sealing and bearing surface area.  It also probably helps to improve pumping performance a bit.

In the next photo we see the back side of the same two pumps:

DSCF1947Notice the stepped hole in the left hand pump.  When re-machining the pump, that step is left in place to ensure that the bushing is securely held in place by the stepped hole, but the inner diameter is enlarged a bit to enable use of a bushing of adequate thickness.

The next photo shows how I re-assemble the pumps, using a gear puller:

DSCF1949Notice the strategically-placed hose clamps at the outer end of the jaws.

DSCF1950Those hose clamps hold the jaws out, away from the bore of the pump, so that I can easily install the 2.95″ diameter piston, shown installed in the next photo:

DSCF1959Also shown in the above photo are the four check valves.  Three of them face outward, and one faces inward.

The next photo shows the same pump with the two aforementioned spacers installed:

DSCF1960Notice that the spacer at the upper right also contains that 5th check valve, which not all pumps have.  As I said earlier, both types of pump seem to work equally well.

The next photo shows the same pump with the gasket installed:

DSCF1963Sorry the lighting isn’t all that good, so things are not easily visible.  So be it.

Next is a close up of the same gasket:

DSCF1964Notice the damage that has been done to the gasket between the 4 and 5 o’clock position due to improper assembly.  Someone else did that.  I reassembled this pump, very carefully, using this gasket, then tested it, and it works well.  But, I have installed this pump on my own vehicle.  It’s not among those that I have for sale.

This check valve, the one that is “backward” from the other three, is the one that sometimes has an o-ring around it and sometimes doesn’t.  The o-ring, if present, is used in place of the rubber ring shown damaged in the photo above.  Gaskets that lack this piece of rubber use a separate o-ring instead.  In pumps that have damaged rings, such as the one shown above, I have occasionally cut away the damaged area and replaced it with an o-ring as is used on the other 3 check valves.

Next is a shot of the above pump being tested on my 1986 Volvo 745:

DSCF1970This particular pump tested at 25″ Hg.  Every one of these dozen pumps tested between 23″ and 29″ Hg.

The 11 pumps that I currently have for sale are shown in the next photo:

DSCF1972The above pumps are not pretty, but in the photo they look a lot dirtier than they actually are.  I make no excuses; they are what they are.  My game is making things work, not making them pretty.  But next time I’ll probably sand blast the pumps while they’re apart.

If you would like to purchase one of these pumps, on an exchange basis, the cost is $120.00 each, plus shipping.  Each pump comes with a 50k mile replacement warranty; if it fails I’ll replace it at no charge.  I do ask for the VIN of the vehicle it’s to be installed on, as well as the odometer reading at the time of installation.  Should the pump be transferred to a different vehicle, the warranty is also transferable; just record and keep the appropriate mileage and VIN information.

My contact information is:

Tom Bryant
32 JBS Way
Wiscasset, Maine 04578


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Review, P-Brake Cables and Shoes, 1998 Volvo V70

I recently purchased some P-Brake parts for a 1998 Volvo V70 from a well-known and reputable vendor.  The Pex 9209756 P-Brake cables and the Pro Parts 271998 P-Brake shoes were so out of spec that I could not install them and had to return them to the vendor.

I have had extremely satisfying dealings with this vendor in the past and consider this particular vendor to be one of “The Good Guys”.  Since I do not feel that the problems I encountered are in any way the fault of the vendor, I will not divulge their name here.

I’m posting this “Review” here solely because it’s the most effective way I can think of to describe the problems to the vendor, whom I have asked to read this post.  When I am satisfied that the problems have been properly addressed, I will remove this post from this blog.

Here’s a shot of the first point of confusion, the packaging for the “Pex 9209756” P-Brake cables:

DSCF1807This would appear to be a Pex part number 4.1073, corresponding to Volvo P/N 35465905 whereas the vendor’s website describes it as Pex 9209756.  I have no explanation for that discrepancy; perhaps the root of the problem is that the vendor sent me the wrong part, but I don’t know that.

Next photo, a shot of the brake handle end of the original Volvo cable (top) and the Pex cable (bottom):

DSCF1808Notice that the Pex cable is about 3/32″ shorter on the brake handle end.  That, in itself, is not a problem, but when combined with the discrepancy in the next photo, it does add to the problem.

Next, the other (wheel) end of the P-Brake cables, original Volvo at the top and Pex at the bottom:

DSCF1809Notice that the Pex cable is about 1/8″ short on this end.  Combine that with the 3/32″ discrepancy on the handle end, and the result is that the inner cable is about 7/32″ too short, either that or the outer sheath is 7/32″ too long.  Either way, the cable is so short that it could not be easily installed, especially in consideration of the problem shown in the next photo:

DSCF1811In the photo above, we see the wheel end of the Pex cable.  It’s sticking out of its socket by about 1/8″.  Try as hard as I might, I could not get that cable shoved in that last 1/8″.

So, add that 1/8″ to the 7/32″ that the cable was short, and you now have a cable that is effectively about 11/32″ (nearly 3/8″) short. I could not install that cable without first removing the hand brake handle from the car’s chassis.  And, even after removing the hand brake handle, it was difficult, and also difficult to stretch the cable into place enough to re-install the handle.

And then, after getting the handle bolted back in place, the cable was so short that I could not pull the handle upward more than about one “click” on its ratchet.  And yes, I did loosen the cable adjustment at the handle as much as possible.  And, BTW, the cable was not yet attached to the shoes at the wheel end, so it was pulled forward as far as it would go.  Still way too short.

So, why couldn’t I slide that cable into its socket at the wheel?  The next few photos show the reasons:

DSCF1812In the photo above, we see that the OD of the o-ring is about 0.845″ for the OEM Volvo cable, but about 0.905″ for the Pex cable, a difference of about 0.060″.  So the o-ring was too big to fit into the socket.

Next is a shot comparing the two o-rings:

DSCF1814The OEM o-ring measures about 0.064″ thick, whereas the Pex o-ring measures about 0.090″, a difference of 0.026″, or roughly .052″ on the diameter.  Hmmmm… remember that the diameter differed by about 0.060″?  Well, the extra 0.008″ is fairly well accounted for by the next photo:


Yep, sure enough, as you can see in the photo above, the diameter of the groove that the o-ring sits in is about 0.008″ bigger for the Pex cable.

In the next photo, the OEM o-ring is at the top and the Pex o-ring is at the bottom.

DSCF1816The size difference is readily apparent.

Another difference between the Volvo and Pex cable is shown in the next photo:

DSCF1818Notice that the innermost diameter of the plastic end is about 0.025″ larger on the Pex cable.  That makes the cable rather difficult to insert into its socket at the wheel.

Onward to the next problem:

DSCF1819Notice in the above photo that the Pex cable is longer between the wheel end on the right and the mounting clamp toward the left of the photo.  Although it’s hard to tell from the photo, that difference is almost exactly 1 inch.

But, it gets worse:

DSCF1821Notice in the photo above that the mounting clamp is not symmetrical; the screw hole is about 1/8″ off center.  Also notice that the clamp on the Pex cable is installed backward, which moves the screw hole about 1/4″ forward of its proper location.  Add that to the 1″ length discrepancy noted above, and you now have a cable that is effectively about 1-1/4″ too long between its two mounting points.  That makes it impossible to properly mount the cable, causing a large bend in the cable and kinking it too much for proper operation.  Totally unacceptable.

Onward to the next problem:

DSCF1830Notice that the crimped ferrule on the OEM cable (top) is round and measures 0.322″, whereas the ferrule on the Pex cable probably started out round but has been crimped to a hexagonal shape.  There are two problems here:

  1. One problem is that the hex does not fit well into the expander, which is designed for a round ferrule.
  2. The bigger problem here is size; the Pex ferrule measures 0.348″, roughly 0.026″ too big to fit into the expander as shown in the next photo:

DSCF1834The round OEM ferrule fits easily into its expander (top).  But the hexagonal Pex ferrule will not fit into its expander without being forced.  Using Vise Grips and screwdrivers, I was able, with difficulty, to force the Pex ferrules into the expanders.  But, then, because I had to return the two cables for the reasons noted herein, I later had to remove those ferrules.  That was extremely difficult and took me about 15 minutes each for the two cables, costing me about 1/2 hour total, just to remove those stupid oversize ferrules from the expanders.

The above comments all pertain to the Pex 9209756 P-Brake cables.  I called the vendor on Friday, 10/16/2015 and requested they send me some replacement cables; this time I ordered Febi 9209756.  The vendor didn’t have any of those in stock, so had to order some for me from their supplier.  The replacement cables arrived here as promised on Tuesday 10/20/2015.  They fit well and were easy to install.  No problems whatsoever with the Febi cables.  But, I did lose more than 4 days of productivity due to my lift being unavailable for other jobs.

And, of course there is the additional expense of paying for shipping on the replacement parts and the cost of shipping the defective parts back.  Overall, it’s a rather aggravating experience.  Then, to add insult to injury, the Pro Parts P-Brake shoes were also defective, which pretty much wasted the rest of day 5.

Now I’m moving on to document what was wrong with the Pro Parts 271998 P-Brake shoes:

DSCF1850Once again, as seen in the above photo, none of the part numbers on the box match the part number I ordered.  I’m not sure why that is.

When I tried to install these Pro Parts P-Brake shoes, I could not get the brand new rotors to slip over the brake shoes.  Not no way, not no how.  And yes, the brake shoes were well-centered, and yes, the expanders (both top and bottom) were loosened as much as possible.

After trying, unsuccessfully, for about a half hour, to install the new rotors, I began to suspect that the problem was too thick a lining on the brake shoes, so I went over to Goodwin’s Volvo and compared them with a brand new OEM set of shoes, as shown in the next photo:

DSCF1852It’s not terribly obvious in the above photo, but the linings are indeed thicker on the Pex shoes (top) than on the OEM Volvo shoes (bottom).  That difference is a bit easier to see in the next photo:


The Volvo shoes are at the top, and the Pex shoes are at the bottom.  The Pex shoe linings are definitely thicker.

After making several measurements of each shoe and averaging the results, I concluded that the Pex shoe linings are about 0.026″ thicker, making their outer diameter about 0.052″ larger than that of the OEM Volvo shoes.  No wonder I couldn’t get the rotors on!

To avoid more lost time, I bought the OEM Volvo shoes and installed them; they went in easily.  I will be returning the Pr0-Parts shoes.

Altogether, I lost more than 5 days of work because of these defective parts (cables and shoes).  And I had to pay extra costs for shipping and for replacement parts. If I were doing this for a living, I’d go broke.


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SU Carburetor Tuning

Today I will discuss tuning of SU carburetors.  Tuning includes mixture adjustment, idle speed adjustment, and synchronization.  It is assumed that your carbs have been properly rebuilt and the jets centered; if not, stop here, because your carbs are likely not tune-able.  Instead, go study one or more of my posts on SU rebuilding, starting with:

The particular carbs in this post are installed in a 1967 Volvo P-1800, owned by a guy in Waterford, Maine whose grandparents bought the car new in Sweden, so it’s a family treasure.  The carbs were rebuilt by the owner, with some assistance from Joe Curto.

Although these particular carbs are HS-6s, on a Volvo P-1800, the procedures described in this post are generally applicable, with only minor variations, to virtually all SU carburetors.

Here’s a photo of the car and its current owner.



And here’s a shot of the carburetors.  These are the nice “3-hole” variety, with threaded holes for screws to hold on the air cleaners, vice the earlier “2-hole” ones, which used bolts and nuts, a lot less convenient.


Here we have a photo of my ancient PSW Tool, which is designed for tuning SU carburetors.  It contains a pair of tubes and wires for balancing the carbs, a jet adjustment wrench, and a (completely useless) “jet centering” tool, which may be seen peeking out of the plastic pocket, just to the left of the jet adjustment wrench.

DSCF1755The jet centering tool is useless because it does not work, nor can I think of any way it could be re-designed to work.  That’s because jets and needles, and jet bearings, are all a bit different, and they really must be centered individually, using the actual parts to ensure proper centering.  Typically, the holes in the jets are a bit off center, so just use your own jet, and your own needle, and center the thing, as shown in my posts on rebuilding.

A tool set similar to my PSW tool is available as item “B” from:

It’s worth having, particularly if you have Type H carbs.  And the wrench, item “C”, is really nice to have.  In my opinion, the “Uni-Syn”, item “A”, is worthless; I can’t think of a less useful tool for adjusting SUs.  And, for reasons noted above, I don’t believe that item “D” (for jet centering) would be of any value, either.

Next is a photo of the PSW tool in use.

DSCF1756But, not everyone has a PSW tool, so I’m going to show you how to make your own synchronization tool from a wire coat hanger.  The homemade one actually works better than the PSW tool for synchronizing and balancing; that’s because the stiffer wires don’t vibrate as much.

Nevertheless, the PSW tool has its uses; the oval tube (at the right in the photo above) being just perfect for adjusting Type H floats, for example.  And that short jet adjustment wrench is really nice to have.

Note that the center-to-center distance between this pair of SUs is about 8-1/2″.



So, cut and bend your coat hanger so it looks something like this.  Notice that the sharp wire ends are bent inward to prevent scratching the dashpot bore holes.  You should read the rest of this post before you make your own synchronizing wires because I’m going to show you what I consider a better design at the end.  But the ones shown in the next photo are the ones I used on this car, so here they are:


The first thing you have to do is to start the car and get it warmed up to normal operating temperature.  If you’re installing carbs that I rebuilt, the jets adjustment nuts will be turned all the way up.  That’s to ensure that the jets are properly centered.

You should turn each jet adjustment nut down about 2-1/2 to 3 turns, then pull your “choke” and start the car.  As the car warms up, push your choke in to lean out the mixture.  Do whatever you have to do to keep the car running at a reasonable speed while it warms up.

Shut the engine off and loosen the linkage between the two carburetors so that each throttle shaft will turn independently.  For Volvo HS-6s, loosen the two nuts that are facing upward, one on each end of the center linkage shaft, as shown in the next photo.  When installing your carbs, make sure those nuts on the linkage face upward; you’ll regret it otherwise.

For other types of SUs, and other makes of cars, the linkage is different, but the principle is the same; you want the two throttle shafts to turn independently, and you don’t want any input from the accelerator pedal.

DSCF1766Also, if necessary, back off the two “fast idle” screws, one on each carburetor, so they don’t contact the “choke” cams and thereby prevent the throttle plates from closing fully.

Now, with the engine still off, put the wires into the carbs as shown in the next photo and align the pointers so they’re both at the same height.

Now, re-start your engine, and adjust the idle screws on the carbs to obtain about 1500 RPM; the exact value isn’t critical, but it should be in the range of 1200-2000 RPM.  You might also check the timing at this point, just to make sure that it isn’t grossly off.  For Volvo B16, B18, and B20 engines, the timing spec is usually given at 1500 RPM, so that’s a good engine speed for checking your timing and for starting to adjust your carburetor mixture.

In the next photo, I’m adjusting the idle screw of one of the carburetors to achieve 1500 rpm while keeping the pointers at the same height to ensure equal flow through each carburetor.  Obviously, you have to adjust both idle screws, alternately, to achieve the goal.

DSCF1760BTW, see that fuel filter, just beneath my right hand?  Get rid of it.  Do not use any fuel filter on your SUs.  Totally unnecessary.  There is nothing that will go through your fuel pump that won’t also go right through your SUs without doing any harm.  Fuel filters on SUs are, quite simply, a breakdown waiting to happen.  You’re better off without them.  And putting a fuel filter upstream of the fuel pump is particularly detrimental, as it can cause vapor lock, starving your engine for fuel.

Well, it’s pretty hard to see in the next photo, but the Tach/Dwell meter shows about 1500 rpm, and the pointers are both at the same height.

DSCF1761Next, adjust each carburetor jet mixture nut while watching the Tach/Dwell meter.  Turn the nuts up and down alternately until you find the position of each nut that maximizes the engine RPM.   It’s not necessary to keep the RPM constant at 1500 RPM.  But you should try to keep it in the range of 1200 to 2000 RPM.

You may have to turn one, or the other, or both, idle screws to maintain equal flow through each carburetor as well as the desired RPM.

I like my analog Tach/Dwell meter much better for adjusting carbs than a digital one.  The analog meter stays relatively steady during adjustment, whereas the digital one I  recently tried jumped around all over the place, making it hard to see the effect of small adjustments of the jets.

DSCF1762Forget about those lift pins under the pistons; they’re useless.  That’s my opinion, anyway.

After maximizing the RPM with one nut, switch to the other and adjust it the same way, then go back to the first one.  Keep at it until you’ve found the point of maximum RPM, where moving either nut, in either direction, causes the RPM to decrease.

You have to wait a few seconds after each adjustment to give the engine time to stabilize at its new RPM; so be patient.



Okay, here we are.  RPM is maximized; pointers are at the same height, and the engine speed is around 1440 RPM, as shown in the next photo:

DSCF1764Note that this analog Tach/Dwell meter has an RPM scale (at the top) for 8 cylinders.  The reading must be doubled for use on a 4-cylinder engine.  So 720 x 2 = 1440 RPM.

Now that you’ve found the point of maximum RPM, you should probably turn each jet adjustment nut downward (i.e., richer) about 1/6 to 1/3 turn (one or two flats).  This seems to help prevent hesitation on acceleration.  So, wait until after you’re able to try your car out on the road, and then decide if you need to richen the mixture by 1 to 2 flats on each carburetor.

Now, adjust the idle speed to about 800 RPM, using the idle screw on each carburetor.  Be sure to keep the pointer wires at the same height to ensure equal flow through each carburetor.

Remember those two linkage rod nuts you loosened a while ago?  Here’s the photo, again:

DSCF1766Well, now it’s time to tighten them.  Unfortunately, I don’t have hands enough to do the job and take pictures too, so I’ll show you two pictures of the process, whereas the job was actually done in one step.

Take a screwdriver and push one of the linkage arms downward until it just touches the bottom of the fork on the end of the throttle shaft, as shown here:

DSCF1767At this point, rather than take a picture as I did, use your other hand to hold a nut driver and tighten the nut while holding the lever arm downward.  See the next photo:

DSCF1768As I said, you really need to hold the lever down at the same time as you’re tightening the nut.  I just don’t have enough hands to do that and take photos too.

Now, do the same operation at the other end of the linkage:

DSCF1769And, of course, you tighten the nut such that the lever arm just touches the bottom of the fork on the end of the throttle shaft.

For Type H carburetors, which have a different center linkage arrangement, just tighten the linkage, being careful to ensure that neither throttle shaft is moved during the process.

At this point, you should grab the throttle linkage at the middle and use it to open both carburetors a bit.  The two pointers should move up simultaneously and at the same rate and height.  If not, recheck your linkage and readjust to ensure that both carburetors open at the same time.

Now it’s time to add oil to the dashpots.  Use Mobil 1, 15W-50:

DSCF1770Nothing else I’ve ever tried works as well.  Nothing.  For more information, refer to:


DSCF1771Fill the dashpots to about 1/4″ below the top of the inner tube.  If you put too much in there, it won’t do any harm, but it will get squeezed out and wasted when you install the dampers.

After installing the dampers, lift each of the two pistons all the way up and use a rag to wipe up any excess oil that gets squeezed out.

Now, before re-installing the air cleaners, go out for a road test, and see how it runs.  You may want to richen the jet adjustment nuts by 1 to 2 flats.

At this time you should also adjust your fast idle screws so they don’t contact the fast idle cams with the “choke” pushed all the way in, but such that they do make contact with the cams as the “choke” cable is pulled out.  Where you leave these screws is pretty much up to your personal preference.

Now it’s time to re-install your air cleaners.

Now, as promised above, here is a photo of my later-design adjustment and synchronization wires:

DSCF1781The bends are at the top of the inner dashpot tubes, rather than at the bottom.  This configuration works a bit better because it holds the top of the wires more steady, with less vibration.  It also makes it less likely that the sharp cut end of a wire might scratch the dashpot tube inside the carburetor.  Also, you can easily cut a little off the bottom end, if you need to, to adjust the height.

Here’s a shot of this later design in use on another P-1800.

DSCF1783Note that the ends of the wires don’t overlap; rather they’re cut so that they almost, but not quite, touch.  That works better; it’s easier to tell if the carburetors pistons are at equal heights.



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