Pierburg squaretop fuel pump vs Brosol squaretop

[Frodge]

I just received a used squaretop fuel pump in he mail. It was advertised as a pierburg unit but it is in fact, a brosol. They look nearly identical. Are there any real world differences between the two? I’m just looking to rebuild it.

[Frodge]

I just finished the preliminary cleaning of the fuel pump body. I want to soak it overnight. Is carb cleaner the best thing to soak with? Is it necessary to remove the internal valve before soaking this? Since that valve is not included in the kit, I don’t want to disturb the Bakelite valve if unecesaary. Thanks.

[baldessariclan]

I recently rebuilt one of each, and found them to be pretty similar for the most part. The overall fit, finish, and function were slightly better on the Pierburg unit, though, in my opinion.

I used carburetor cleaner as part of the cleaning process on the ones I rebuilt. I did remove that internal valve before soaking, as well -- didn't want that Bakelite disc to get eaten / melted by the carb cleaner. Just use a small punch and hammer (from the top side) to carefully drive out the aluminum retaining ring for that valve. Also be careful not to lose the small spring underneath.

Reinstall in similar manner, and finish by lightly peening the housing edges around the ring -- you should be able to see / use the old peening marks. IIRC, the Pierburg unit had several around the periphery, while the Brosol had fewer.

Note also that I wouldn't recommend soaking aluminum parts any longer than 2 - 3 hours at a time in carb cleaner without rinsing & checking in-between -- it's pretty harsh stuff, and sometimes seems to frost / "eat" smooth finished surfaces on aluminum a bit if left in longer than that.

[Pruneman99]

[Cusser]

[Frodge]

What is the correct Wolfsburg west kit? There are two listed. One for slip style fittings and one for screw style fittings. I don’t know what fittings they’re talking about....

One more question I have is the actual diaphragm. The main diaphragm that was in there is in pretty damned good shape. It’s nice and pliable. Should it be replaced regardless? It looks like his pump was rebuilt at one point because of the markings from a screwdriver on the screws that hold it together. My gut tells me its a vw diaphragm that was replace at some point. No cracking or tearing. What would you do?

[Cusser]

[Frodge]

I have a slip style inlet and outlet. I am also looking at their two kits and don’t know what the inlet and outlets have to do with either kit on their site. I also can’t see a difference in the twonkits they supply.

[EverettB]

Screw inlet kit
http://www.wolfsburgwest.com/cart/DetailsList.cfm?ID=111198553

Slip style kit
http://www.wolfsburgwest.com/cart/DetailsList.cfm?ID=111198555

Screw kit has the round seal for the screw-inlet pump top cap.

They also show some parts you don't need but are used in the slip style pump, not sure why.
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[Frodge]

Thanks. Which one is needed for this?
https://hotvws.com/images/hot_vws_articles/45/pump01ab_photo1_620px.jpg

[EverettB]

[Frodge]

Excellent. Thanks for clearing that up. I need the slip fit.

[67rustavenger]

I recently rebuilt a Pierburg slip fitting pump with a WW kit.

The main thing about the new WW rebuild kits is that they now have Effbee diaphragms. These have the correct pump rod length and fit very well.
The diaphragm id correct and compatible with today's crap fuels.

The Borsol pumps do not have the clips that hold the actuating lever pivot shaft in the pump body. Fortunately, the WW rebuild kits have a new pivot shaft with the clips included in the kits. A nice upgrade.

The pump rebuild is pretty straight forward if you lay out the parts in the order that you disassemble the pump and then reverse the process when everything is clean and ready for reassembly.

Soaking overnight in Berryman's is a good idea.
I soda blasted the pump body and brass bits to give it a almost new exterior look. YMMV.

Make sure to lube the heck out of the lower portions of the pump before installing it back on the engine.

When reassembled the pump. I did the top end first. Then did the bottom half. When It came to putting the two parts together. I installed the bottom half on my engine and moved the crank to get the pump stroke at it's highest level. Then installed the screws that seal the top and bottom with the diaphragm in the relaxed position.

Good Luck.
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[Frodge]

Thanks for the instruction. The Brosol I was sent has the circlips on the rod. I also have a preload tool. Thanks a bunch.

[baldessariclan]

The following was my own personal experience with the Wolfsburg West rebuild kit for the Pierburg / Brosol fuel pumps. I ordered and received a rebuild kit from them earlier this year (Feb. 2018). What I got was a kit with good main diaphragm, but most of the other parts were pretty shoddy and/or non-functional. See pics / descriptions below.

I kept and used the main diaphragm, but returned the rest to them for a (partial) refund.

The current picture on website (as of June 2018) for their rebuild kit does look like it has different / better components now — maybe they’re ok at this point?


The main pump diaphragm and spring seem to exactly match the old original component and works fine (old/original left, new right):

The new gasket set looked so-so at best, quality-wise (old/original on left, new on right):

Spring set seemed more-or-less similar (old left, new right) — I chose to reuse the old / original springs:

The new rocker pin looked to be of softer steel and/or not plated, compared to original. The original internal valve disc was made of Bakelite / phenolic material, while new valve disc was made of some sort of rubber. Once again, chose to reuse the old parts instead of the new (old left, new right):

Both the new rocker arm and internal valve retainer were received with corrosion on them. The new internal valve retainer was also of different diameter than the original, and too loose to hold in the corresponding hole in pump body. Yet again, I chose to reuse the original parts (old left, new right):

Original internal valve retainer:

New internal valve retainer — too small:

The anti-backflow valve / diaphragm didn’t fit or work right either — central rubber valve disc sat too deep. Returned it and ordered a NOS one from another vendor (old left, new right):

Old valve assembly seemed to sit and seal correctly (unfortunately however, old diaphragm was too dried-out and stiff to reuse):

On new part, had to press down very hard for inner gasket to seal, causing outer diaphragm to deform excessively. Internal spring not strong enough to make it seal / function correctly when reassembled. I ended up having to order and use a separate NOS component to make this part of pump function correctly.

However, Wolfburg West’s current picture for this pump kit does seem to show different / better quality components now, though (June 2018). Maybe it’s a better kit nowadays — ??

Please let us know if your current rebuild kit from WW seems of better quality than what I show in my earlier pics from above...

[kreemoweet]

There were some manufacturers in Mexico/South America who made the fuel pumps under license from Pierburg, and were
virtually identical. If the pump has the triangular "APG" trademark on it, I think it would be fair to call it a Pierburg pump.

That's one outstanding analysis by baldessariclan of the deficiencies of the pump rebuild kits that WW is/was selling. I had all of the exact same issues
with the WW kit several years ago, and WW was informed at that time, in detail, of all the problems with it. They nevertheless chose to continue
selling the same bogus parts, at least up to February of this year.
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[AlmostHeavenWV_VW]

I'll just drop this here re: Wolfsburg West pump rebuild kits. Seems they are of much better quality nowadays:
From the main Pierburg thread in the stickies:
https://www.thesamba.com/vw/forum/viewtopic.php?t=...p;start=60

[Frodge]

Great info guys! Thanks for all that information, it’s extremely helpful. I’ll be taking my pump body out of the Berrymans in a little bit. I asked earlier About the diaphragm I took out. It looks like an original vw one. It was replaced somewhere along the way in this pump because I can see the marking on the screws from being removed somewhere along the line. I inspected this diagram and it still seems supple with no cracks. Not being cheap, I just know these are superior, should I still use this? I can snap a photo. It look to my eyes as being perfect.

[kreemoweet]

[AlmostHeavenWV_VW]