mj 4.0 rear main seal

[PaulL]

My 88 mj had a bad rear main seal leak. I had it replaced and it still leaks bad. The mechanic said the crank had a nic in it. What options do I have to repair it?

[87MJTIM]

A sleeve over the end of the crank, or replace the crank.

 

https://www.rockauto.com/en/moreinfo.php?pk=257668&cc=1180178&jsn=9

[ghetdjc320]

1 hour ago, 87MJTIM said:

A sleeve over the end of the crank, or replace the crank.

 

https://www.rockauto.com/en/moreinfo.php?pk=257668&cc=1180178&jsn=9

 Whoever installed the rear main should have felt the journal for any burs. 

[Pete M]

is the nick in a place that the double-lip RMS can fix?

[Eagle]

2 hours ago, Pete M said:

is the nick in a place that the double-lip RMS can fix?

 

Pete beat me to it. One of the aftermarket gasket makers has a rear main seal that has two wiper lips on it. The second wiper rides on a part of the crank that won't be worn, so it should seal even if the crank is scored. Be sure to lube the new seal with Vaseline when you install it. You should never install a seal like that dry. Just don't get Vaseline on the ends where they have to be glued together with RTV.

[Minuit]

In addition to the above, the factory service manual also specifies a specific place on the #7 main bearing cap where anaerobic sealant (and it has to be anaerobic sealant) is supposed to be placed. I'd know, because I got fleeced at the dealership when I did the RMS in my '91. I doubt most mechanics know this. A piece of my engine block even came out with the seal, but I've put something like 30k miles on it since with very little oil leakage from that area.

 

 

That graphic isn't present in the '91 FSM I have, but it is in the '94 FSM.