Fuel pump leak

[ncsurfer]

Hi everyone, I am trying to get the 280sl ready for the 50th Anniversary and have it in the shop to finish up a few items. Got a call from the owner today telling me I have a slight fuel pump leak. He said it seems to be coming from the brown plastic at or on the electrical connection on the pump. I told him I would post it on this site to see if there s a seal or gasket in this area. I had taken the pump apart last year to get it running, but I did not put in new seals. Any help would be appreciated. If not, he will have to take it apart again and go through it. Thanks, ncsurfer

[Benz Dr.]

There are O rings around each electrical terminal inside the pump housing. You will need to melt the solder on each terminal and remove the wires to install new O rings.

[ncsurfer]

Thank you Dr. Benz, I really appreciate it. Since I have to take the pump apart, should I replace the other O rings as well? Is there a rebuild kit available that includes all of the O rings?
Thanks....

[KevinC]

Try sending PM to George Des (find him on the "Members" tab). He has assembled what you'll need and sells the parts very reasonably.

[ncsurfer]

Thanks Kevin, will do....

[George Des]

If the leak is from the terminal area, you will need to disassemble the pump and desolder as Dan mentioned. The orings under the terminals have a square cross section. Sourcing suitable metric rings with this cross section is difficult. Some have had luck using a round cross section ring. I have not been so lucky. What I have done is to source some non metric square section rings from McMaster Carr and custom fit them to a tight fit by carefully cutting out a very small section with a razor blade and carefully supergluing the ends together to form the ring. Sounds crazy but this is exactly how custom rings are fabricated. Once you form the ring, pack the terminal recess with a little Permatex non hardening gasket sealer and place the new ring and then insert the terminal through the ring. Resolder the terminals. I would replace the other 4 orings while I am in there. You should be good to go

[George Des]

Regarding the square cross section oring. Unfortunately, I'm not where I can get to the size oring that I've used to do this custom fitting. As I recall it was the SAE size closest to the metric round that some have suggested will work. I had to experiment with a few sizes before I found the one that would work best.  The key is to get a very tight fit on both the inside and outside of the ring when placed in the terminal recess. The Permatex will help to lubricate the plastic terminal so it can be inserted through the rings and will help it seat better. This procedure should be added to the Tech Manual if someone here know how to do that. This is a common source of leaks on the short style pump. Hope this helps.

George