Persistent Oil Leak...getting worse...

[Keithc8]

I can not see an engine builder taking an engine that is running perfectly fine back because of an oil leak on a used block. I tell everyone that gets a FE engine do not be surprised if it leaks at the rear main seal. I have built enough of the new and old ones to know. We have tried evrything that we can find and since we do not make the block or machine the seal area we can not stand behind rear main seal leaks. We do check them on the dyno and if they leak we do all that we can to fix them. We have even gotten Chrysler Big Block rear main seals and worked on them for the blocks that seem to be a little big in the rear seal area and have had some suddes doing that in bad situations. It is not only the size of the seal area it is also how it is machined in relationship to the center of the mains. We machine the early 302 and 351 blocks that we do for a one piece rear main seal and find the original two piece seal area of center as much as .030 and it is hard to seal up something that is that much of center. The blue prints for the origins FE engines had most of the tolerances at a plus or minus .025 for areas like this. Even the lifter bores are listed with a plus or minus .025 tolerance for their location. This means that you could have one bore plus .025 and another minus .025. This is mone reason the factory used a rope seal. I have not been able to find any rope seal of late and then they had their own problems. I have had this with all of the original and new FE blocks. You can not machine these blocks for a one piece seal because of the size of the flywheel flange and bolt pattern. Now if we had cranks made with a small block bolt pattern and we could get flywheels with a small block bolt pattern with a 184 teeth we could do this. Maybe I need to look into a new way to go and any ideal would be nice. If I get a FE engine that runs good and is giving me no problems and only leaks a one to two inch circle after setting over night I am happy. Good luck, Keith Craft