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'90 XJ 4.0L

tjmotter

NAXJA Forum User
NAXJA Member
Location
Texas
Background:
The engine has 198,000 miles. I replaced the rear main seal on this engine about 12,000 miles ago. I don't put a lot of miles on this vehicle so this equates to about 6 years. It has been tight and dry ever since with absolutely no issues.


In prep for a 140mile drive I took it into a local shop for an oil change and it appears that they over filled it. I didn't check before the drive but when I parked it after the long drive I found a puddle of oil under the rear of the engine this morning. I immediately checked the oil level and it is about 1/2 to 3/4 of a quart over the fill line.



I strongly suspect that the over-fill is the cause of my leak but my question is: is the rear main seal shot (again) or will it re-seal after I drain some oil?


thoughts?
Todd
 
On any suspected rear main seal leak start at the top and work your way down. I guess I would start by removing the excess oil. Nearly every oil leak on the XJ will run down to the rear main seal area and make it look like you have a rear main leak when it could be a number of other leaks causing it.

Valvecover -> Distributor gasket (replace with oring) ->Oil filter adapter O-rings -> Front timing cover seal/gasket -> then start looking at your rear main.

Another less common area to check is the passenger side of the head gasket. That is a non pressurized part on the head gasket that simply seals the oil galley for oil from the head to drain back down into the engine. It's possible for that portion of the gasket to spring a leak and again when that oil runs down the block it makes it's way down to the rear main seal area and looks like a rear main leak.

You could also order up a dye kit and a UV light. This makes finding leaks and their sources pretty dang easy.
 
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