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Late style fuel pump oil leak

Posted: Sun May 12, 2019 11:48 am
by jule block
I am chasing a not insignificant oil leak that now appears to be coming from the fuel pump. At first I thought the 3rd piece might be leaking where the external oil circulation boss is, sent it out west for rewarding but does not appear to have solved the problem. My question is, can the seal on the shaft of the later style fuel pump leak a significant amount of oil? Enough to coat the exhaust and drip from the side of the 3rd piece? There is no evidence of oil leaking from any where else.
Thanks for any help,
Jule

Re: Late style fuel pump oil leak

Posted: Sun May 12, 2019 1:03 pm
by Chuck Allard
Yes, if you don't have the proper O-ring installed.

Re: Late style fuel pump oil leak

Posted: Sun May 12, 2019 2:02 pm
by jule block
It has a new o-ring. I'm wondering if the seal on the shaft can leak very much and then out the external weep hole.

Re: Late style fuel pump oil leak

Posted: Sun May 12, 2019 8:09 pm
by Chuck Allard
Stoddard sells the proper O ring 999-701-043-50 that won't leak. Some in the engine gasket sets DO leak. When they do, it's a significant leak around the fuel pump where it goes into the 3rd piece.

Re: Late style fuel pump oil leak

Posted: Sun May 12, 2019 9:27 pm
by jule block
Well it is a significant leak and easy enough to put in a new seal. Wish I could get it next day.

Re: Late style fuel pump oil leak

Posted: Sun May 12, 2019 10:38 pm
by Mark Roth
I had that leak recently. It puts out quite a bit of oil.

Re: Late style fuel pump oil leak

Posted: Sun May 12, 2019 11:37 pm
by Mike Wilson
You're close to Stoddard. My guess is they can get it to you fast.

Mike

Re: Late style fuel pump oil leak

Posted: Mon May 13, 2019 10:42 am
by MICHAEL FOSTER
I also had a late style fuel pump leak around the pump shaft . Took pump off and disassembled pump to find that very small seal staked to inside of pump had come loose allowing oil to leak profusely around shaft into pump and from there down engine. Replaced pump with rebuilt and never looked back.
Never did get around to attempting fix on leaking pump.

Michael Foster

Re: Late style fuel pump oil leak

Posted: Mon May 13, 2019 11:06 am
by Dave Wildrick
jule block wrote:
Sun May 12, 2019 9:27 pm
Well it is a significant leak and easy enough to put in a new seal. Wish I could get it next day.
Had the same shaft seal leak on a C pump a few years ago. I believe the new rebuild kits include this seal, whereas the older ones did not. You might want to ask Stoddard's about this. Took me quite a while to find the leak source before I actually saw oil pumping out of the vent holes on the back side of the pump.

Re: Late style fuel pump oil leak

Posted: Mon May 13, 2019 9:46 pm
by jule block
Thanks, I am waiting for both seals to arrive before I dig in and hopefully solve the issue

Re: Late style fuel pump oil leak

Posted: Wed May 15, 2019 11:17 am
by Mike Horton
The factory 912 supplement refers to this "seal", as a "wiper. be sure to install the "seal, in the correct direction, to keep the oil in. Also, re-stake the part, into the housing. As Dave said, my early Pierburg kits didn't contain this part, but my last, about a year ago, did,

Re: Late style fuel pump oil leak

Posted: Wed May 15, 2019 2:06 pm
by jule block
Pump is now apart and full of oil below the diaphragm. Did not appear that the "wiper" seal was peened in place. Amazing how much oil it could pump out the weep hole. Now the wait for parts.

Re: Late style fuel pump oil leak

Posted: Thu Jun 06, 2019 11:22 pm
by Ken Lubke
Had the same issue of the leak. I bet I took that pump apart too many times and finally found that the shaft seal comes with metal sleeve. Seal was gone but metal sleeve still stuck in position. A pik and some patience, and the metal piece popped out. New seal pressed in and peened. All good and no leaks. Yipee

Re: Late style fuel pump oil leak

Posted: Thu Jun 06, 2019 11:48 pm
by Mike Horton
I've been rebuilding my spare S90 engine, and just this afternoon, ran the fresh overhauled pump, and fresh split shaft Solex, on the old engine, to check for leaks. So far, all I had to do was tighten the 8mm fuel pump screen cap bolt, to clear a slight fuel leak. Outside, with a fire extinguisher on hand.

I made a seal/wiper removal tool, from one of those old advertising pocket screwdrivers, with a magnet in the handle end, which companies gave away, as gifts, by bending a roughly 90* bend on the tip, and went through the shaft hole, and lightly drove the old one out. Be sure to place the lip seal, to keep the Fuel in the pump (higher pressure), & oil in the third piece, and re-stake it after using a small socket to drive the new seal into the bore.

A bit "fidgety", but basic fix.

Re: Late style fuel pump oil leak

Posted: Fri Jun 07, 2019 7:23 am
by jule block
I put my old style pump back on and amazing no leaks. I'll rebuild the newer pump but is there any good reason not to continue to use the old style?