Repeating Oil Leak in 88 YJ. -
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post #1 of 5 Old 02-21-2013, 08:38 AM Thread Starter
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1988 YJ Wrangler 
Join Date: Feb 2013
Location: Manchester
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Repeating Oil Leak in 88 YJ.

Hi there. After years of having CJ's, we picked up an 88 Wrangler YJ automatic, 6 cylinder, 4.2 for her. Guy told us it needed a new rear main seal & it did have drops of oil each night in driveway. Great deal. Ran her for a couple days to see how bad leak was & it was steady drops. Looked all that up on here and other sites & got great information on what to do/not to do & also bought a Haynes Manual. Pulled it into my shop after degreasing at car wash, carefully followed the directions, & replaced the rear main seal (yes, facing the correct wayl) & oil pan gasket. Will say the upper main seal went right in with no issues or concerns as did the entire job. Also, while we were into it, gave her some more care & replaced spark plugs, rebuilt existing carb, adjusted idle, new oil filter, new fuel filter, new air filter, & fresh oil (high mileage 5w30), etc. Fired her up and oil came gushing out in same location. Gushing.

Enough to make us go what the heck? (no, heck was not said.)

So, went back and took everything apart again. *Will say the new oil that we drained out looks really dark and thicker already. put in another new rear main seal, used black RTV seal this time (let dry 24 hours), put everything back together, (oil pan gasket looked fine, no issues with over tightening bolts), filled her back up with oil.

Fired her back up & oil not gushing out but definitely steady drops worse than what we started with before doing anything. Again, what the heck? (no, heck was not said, but can't say here what was actually said ).

So, let it run a little thinking maybe it just needs to seal up some, or maybe this is just residual oil leaking out. Called it a night. Went back up this morning & a lot of oil leaked out overnight (puddled & ran to side).

So, what is my next step as my girl is like really, how long have you worked on Jeeps and you can't figure this out? I've looked in the Haynes Manual & online & everything mentioned so far that I've read, I've checked. I haven't overtightened the oil pan bolts & the gasket appears fine. The leak is coming right at the bell housing plate & it's a lot.

I'll take any suggestions at all.



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post #2 of 5 Old 02-21-2013, 12:56 PM
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1995 YJ Wrangler 
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Just a thought...could it be dripping out the back of the valve cover or somewhere up higher on the engine?

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post #3 of 5 Old 02-21-2013, 04:45 PM
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1998 ZJ 
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i just picked up a 90 4.2 & same thing. first check all valve cover bolts.all mine where so loose i could almost pull them right out. second after i did that i got a steady stream of oil coming out bottom of bellhousing when running. long story short the pcv valve & breather hose on valve cover where clogged causing too much backpressure making engine drip. i was under jeep about to start a new RMS when i pulled off pcv & hose & it all stopped. hope this helps. good luck. with a jeep it never ends.....
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post #4 of 5 Old 02-21-2013, 07:12 PM
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1988 YJ Wrangler 
Join Date: Aug 2004
Location: Versailles
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I bought mine like that. It was the oil sending units leaking on the starter and running out at the rear main.

Anything is possible if you don't know what you are talking about.
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post #5 of 5 Old 02-26-2013, 08:33 AM Thread Starter
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1988 YJ Wrangler 
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Location: Manchester
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Replaced the RMS again. This time, really cleaned out the upper part before putting the top seal in. Used compressed air, pipe cleaners & blew the heck out of it. Only used little RTV on the ears of the bottom seal & the chamfered edge. After 1 day, looks like only little bit of residual oil leaking little bit, nothing like the gusher I had. Hopefully with doing that, using the 10w30 oil, putting in some stop leak, I'll be ok. Checked again this morning & no leak at all. Hopefully, I got it. Thanks for the help!
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