help understanding why rear main seal can leak if in too deep

[pampadori]

I recently reinstalled my crank and rods and sealed up my case. I had slid the RMS onto my 2.7L crankshaft and then set it in the one case half and then got the other case half on top and all closed up. Only then did i realize that there is a recommended depth for the RMS and installing it too far in can cause leaks.

I don't, however, understand why that would cause a leak. The crank is flat all the way back to that little ring thing that I figured was there to prevent from pushing the seal too far in. Now i'm not sure what that ring's purpose is. The case seal area appears to allow you to have the seal in all the way as well.

Can anyone explain why this causes a leak and maybe explain it with a picture or something? I'm just not getting it.

I'll likely remove the new flywheel bolts (waste of money there) and dig the seal out and replace it with a new one at the correct depth unless someone tells me otherwise.

Here is a pic of the seal...

[KTL]

Good question. The seal shouldn't leak if it's installed squarely. Plus, the inside diameter of the seal should seal as well or better since it's riding on a new location of the crank. That's assuming the previous seal was installed flush.

But it's hard to install the seal squarely when you push it below the surface of the case. The case surface gives you a nice reference of uniform seal depth.

I wouldn't worry about the flywheel bolts. There's nothing in the factory repair manual documentation that indicates these bolts are a one-time-use-only bolt. I have reused the smaller M10x1.25 bolts on 9 bolt crankshafts. I see no reason why you can't use the larger M12x1.5 bolts in the 6 bolt crank. Seems to be some rumor out there that got started about these bolts being "stretch bolts" and that's not the case.

But I do see you used the Curil T green goop around the seal bore. Not sure how it came to be a recommendation to use that product for installing the crank seals. A lot of people have experienced leaks when the seal somehow manages to walk its way out of the bore, thanks to that sticky non hardening stuff allowing the seal to move out of position.

[boyt911sc]

Originally Posted by pampadori

I recently reinstalled my crank and rods and sealed up my case. I had slid the RMS onto my 2.7L crankshaft and then set it in the one case half and then got the other case half on top and all closed up. Only then did i realize that there is a recommended depth for the RMS and installing it too far in can cause leaks.

I don't, however, understand why that would cause a leak. The crank is flat all the way back to that little ring thing that I figured was there to prevent from pushing the seal too far in. Now i'm not sure what that ring's purpose is. The case seal area appears to allow you to have the seal in all the way as well.

Can anyone explain why this causes a leak and maybe explain it with a picture or something? I'm just not getting it.

I'll likely remove the new flywheel bolts (waste of money there) and dig the seal out and replace it with a new one at the correct depth unless someone tells me otherwise.

Here is a pic of the seal...

Shaun,

Next time you have the rear main seal out, you could do some measurement where the lip oil seal is located with respect to the crankshaft. In your picture, it looks like the oil seal is recessed about 2+ mm and that would put the oil seal lip very close to the edge of the circular sealing surface for your crankshaft.

Tony

[yelcab1]

looks good to me. but I might be seeing some kind of optical illusion.