Pierburg square-top pump leaking from filter cover

[kpf]

Hi all,

I assembled my restored square-top pump, installed it, and after I attached the fuel line, I noticed it was leaking. I had read previous threads in which people tightened up all the various screws to resolve leaks, so I did that. I finally realized that the culprit is the big bolt that covers the built-in filter. The rebuild kit included one orange gasket for that, but maybe it isn't thick enough. It feels like maybe the bolt has bottomed out without completely sealing. It is close, but still leaking.

Can I double-up two of the orange gaskets (I'd have to buy another rebuild kit I suppose...)? Any other ideas?


Thank you,
Kris
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1971 Super Beetle

[wcfvw69]

[kpf]

Thank you very much for your advice, Bill. I'll take a close look at the casting to see if I can find any cracks. I've ordered another rebuild kit in order to get a second gasket...


Regards,
Kris
_________________
1971 Super Beetle

[wcfvw69]

[bluebus86]

many an autoparts store, hardware store carry gaskets, or sheets of gasket material so you can cut your own.

Bug On!
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[Glenn]

[kpf]

[kpf]

The pump leaks just the same with two gaskets as it did with one. I can't see any defect, but there must be some small crack or something. It's a tiny leak. It basically only shows up overnight. The next day there is "sweat" on the surface of the filter section of the pump, and of course the whole place stinks of gasoline.

Shopping for another new pump now...
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1971 Super Beetle

[mukluk]

I'd try some gasket shellac on the plug threads and packing/gasket to see if that stops your fuel seep before replacing the pump. It'll seal up any imperfections and treat the gasket material if it's wicking on the offhand, and it doesn't make removal difficult in the future.
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1960 Ragtop w/Semaphores "Inga"

[sb001]

There is a product I've seen at Dollar General called "Seal-All" I'm sure other places have it too, not very expensive and is oil and gasoline resistant

https://www.dollargeneral.com/seal-all-contact-adhesive-and-sealant-2-oz.html?_br_psugg_q=seal+all

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I'm the humblest guy on this board.

1969 autostick sedan, family owned since new
1600 SP engine
Solex 30 PICT 3 carburetor
Bosch 113905205AE autostick distributor

[Cusser]

Note that gasoline resistant doesn't mean that 24/7 contact with gasoline is OK !!!
_________________
1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[bluebus86]

assemble without gasket, and then hold up to bright light, with magnification if your eyes are weak like mine, look for warpage of the cover or base. And /or, try to put a slim feeler gage between the surfaces, if the gage slips in between the cover and base in some spots, then the part is warped, manytimes near the screw holes, the metal base or cover gets distorted, from decades of being over tight. the two mating surfaces no longer are planar, no longer flat the distorted metal can be filed or sanded flat again by removing the high spots, which often are around the screw holes

Bug On!
_________________
Help Prevent VW Engine Fires, see this link.....Engine safety wire information

Stop introducing dirt into your oil when adjusting valves ... https://www.thesamba.com/vw/forum/viewtopic.php?t=683022

[wcfvw69]

The fuel filter plug area is an unusual area for a leak. I've never seen a crack there restoring hundreds of these pumps. I can see it happen though if someone cranked down on the 13MM brass plug.

I'd look carefully for a leak at the top cover area. Many people do not level that plate when rebuilding them. They can leak at the top and appear to be leaking elsewhere.
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[Meiang]

Minor scratch marks or minor buildup of gasket material can cause a leak.

Two gaskets should never be used on a pressure sealing service, even on a low pressure service such as a fuel pump.

The factory sealing gasket for the filter bolt is 1.2mm thick. The bolt bottoms out with about 0.3-0.4mm clearance. So there is plenty of gasket crush available.

With some aftermarket kits, the diaphram under the top cover does not fit that well and can cause leaks. Sometimes the diaphram rubber and the gasket material is too thick again this can cause leaks. The factory diaphram is 0.2mm thick and the gasket 0.36mm thick.

You did not mention whether you have rebuilt a pump that you have previously used or it is a used pump which you have obtained without any operational experience - ie did it work before?.

Pictures of the sealing surfaces of your fuel pump would be useful.

The picture below is of a good example of the sealing surface for the filter bolt. No leaks after a rebuild.

The picture below is a bad example of the filter bold sealing face and should be replaced.

The pictures below are a good examples of the top cover sealing faces. No leaks after a rebuild.

I should mention that the above fuel pump was rebuilt after 500,000+ miles (it was the original fuel pump) and no work was required to resurface gasket surfaces.

[kpf]

[kpf]

Thank you all for your suggestions. I won't be able to work on it again for another week or two. When I find out more, I'll post it here.


Thank you,
Kris
_________________
1971 Super Beetle

[sb001]