993tt oil scavenge pump retrofit question

[Jmattiko]

Hi.

I have a 90' C4 converted by Protomotive to a stage 4 twin turbo.

During an engine refresh I did recently I installed a 993TT turbo oil scavenging pump to capture and return the post turbo oil back to the case. Old Protomotive design used a gravity feed back to a tube welded to the lower valve covers.


Am having flywheel seal leaks now that all is back together. Second seal did same thing despite what I thought was much care. Have rebuilt air cooled 964 engine in past without leaks so I think I have decent knowledge and skill.

Red posts on seal thoughts... Did no see anything definitive on root cause for situations with no crank scoring or other defect issues.


QUESTION: Is it at all conceivable that my 993tt scavenge pump is contributing to my RMS leak? Did not make internal provisions for the 993 part as it looked pretty simple/obvious.

Any thoughts or typical flywheel seal issue that just needs sorted?

Thanks

Joe.

[Walt Fricke]

Joe

I bought a reasonably fresh NA race motor. Seller said it had a flywheel seal leak, and provided a new seal he hadn't gotten around to installing.

I pulled the flywheel. There was a leak, all right, but the patterns of dust and so on on the seal did not look like what I'd expect if the leak were from the crank to seal face.

I replaced it, and the leak was still there. Crank did not look like it needed a sleeve, and I installed the new seal at a small offset from the old one. It looked like it might be from the case parting line where that meets the seal surface. Curil-T on the new seal did not solve the problem, though it is one I can live with on a race motor where I know I will have to get in there after every track weekend with brake cleaner and rags anyway.

I don't think my leak is due to excess crankcase pressure, because I could see the leak continue with the flywheel off. I added extra epoxy over all plugs in the area, to no apparent benefit.
With the flywheel on, hard to tell since residual oil spread around will migrate down over time.
So I don't have much to say to help you.