Nismobishi
Well-Known Member
I did not. Please tell me more about this!
How much rear main seal oil loss is considered normal for our cars?
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4406bbl
Well-Known Member
There is some truth to this, when chrysler built the 360 no rope seals were used and the crank had lines narrower so the seal had a smooth surface. The problem with some big blocks is how the groove is machined in the block. It is usually on the passenger side that the seal is barely touching the crank because the groove is too deep I assume. In the 70s with a MOPAR neoprene seal I never had a leaker, now with the red/brown Vinton seal I have had 2. The fix in my case was to pull the crank, install the seal and retainer, then you see the problem. In both cases the lips on the 2 seal ends were out of alignment by
.020, the fix was when installing pry the passenger side forward by that .020. This is why a fastfish seal fixs a lot of them because with the seal cut in the retainer it guides the retainer into alignment. Some still leak because the groove in the block just does not let the seal touch the crank enough, usually on the passenger side so far for me. I have fixed that by epoxying some
.010-.020 shim material in the groove, and offsetting the seal about a quarter turn. When you remove the crank and look close, it all becomes clear. I also never put in a seal and trust it, it is always engine on blocks with crank pointing down, pour oil in, it should not leak.....when you do this you will see it is always where the seal meets the crank, usually near the crank parting line, usually passenger side. A .020 fatter seal would fix this, but maybe that would not last in the engine, but it sure looks to me like the 440 seals are not as tight to the crank as the 360 seal. The pics show the narrowed lines of the seal area of a 360 crank, for which a rope seal was never used.
4406bbl
Well-Known Member
On this block the drivers side of the retainer needed to be flush with the back of the block for perfect alignment, and moved .020 forward to align on the passenger side. No way to know this in car. The retainer slides a lot, always offset the seal in problem blocks if changing in the car or use the fastfish seal, or a rope. The rear main cap should also be slide forward until the relief groove lines up, so the seal retainer can move forward as needed. Polishing the grooves all the way our will guarantee a leak as the crank will be substantially smaller, maybe a slight polish and fill the grooves with epoxy/ jb weld.
R413
Well-Known Member
It all this mystery surrounding it, and 3 page long threads With all these “must do items”. I think this causes leaks, just put the seal in and don’t make a big thing about it.
i use fel-pro rubber seals and I don’t do anything to the grooves on the crank, seals fine with no leaks.
i use fel-pro rubber seals and I don’t do anything to the grooves on the crank, seals fine with no leaks.
Nismobishi
Well-Known Member
Honestly, I think my silicone job on the base of the cap or the side seals has a small leak. I don't think it's the seal itself. I'm just going to redo it but instead of using of the side seals I will pump silicone into the side channels until it comes out of the seams.
I agree that the side seals are likely the cause of a majority of rear main seal leaks. I personally found it hard to get them installed without them slipping out of the retainer; it took me a couple of tries.
I think the Mancini instructions said it very well: After after you install the retainer, if ANY part of the side seals are sticking up, then STOP - do NOT trim them. Take it out and do it again. The side seals are the exact length they need to be. If you trim the top it means they slid up from the bottom, creating a gap that allows oil to leak.
I think the Mancini instructions said it very well: After after you install the retainer, if ANY part of the side seals are sticking up, then STOP - do NOT trim them. Take it out and do it again. The side seals are the exact length they need to be. If you trim the top it means they slid up from the bottom, creating a gap that allows oil to leak.
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