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Old 08-22-2014, 01:22 PM   #1
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oil dripping out since last night

Hello team,
My Jeep started a nasty leak last evening on my way home. Im attaching the pictures here. Can you please let me know what this could be?

I looked up online and this is the most hits I get:
MJR Features: Jeep Tech Writeups, Installations & Articles » Rear Main Seal Removal and Installation
1989 Jeep Wrangler YJ (Sahara), 5 Speed manual, 4.2 Inline. 4.5 inch rough country lift with 33 inch tires.
214K miles and counting.
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Old 08-22-2014, 06:54 PM   #2
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hate to say it but that's what it looks to be,will have to drop the tranny to fix it.not that hard to do,just takes time.might want to think about putting in a new clutch kit while it's out....russ

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Old 08-22-2014, 07:11 PM   #3
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The 4.2L has a 2-piece rear main seal. It doesn't require dropping the trans to replace, although you do have to drop the oil pan and remove a couple main journal bearing caps to do the replacement.

If that indeed is the oil leak. The 1st place I would check is the back side of the valve cover. I replaced my rear main thinking that was my oil leak only to find out that after I did the replacement the leak was still there. Turned out to be the rear of the valve cover gasket that was the culprit. But a rear main is a common seal to fail on the 4.2L as well.

Usually starts leaking after a bad PCV valve. The 4.2L is noted for having high crank case pressure, and if the PCV valve starts to clog or goes bad, it will almost instantly take out either the rear main or the valve cover gasket, and when it gets real bad you will see oil spew out of the dip stick tube as well as where the distributor meets the block.
'87 YJ, 4.2L built and bored, 8" of lift, 8.8 rear, AX15/NP 231J, Tom Woods drive shafts, Flat fenders, 12,000LB winch, Custom bumpers, Rattle can paint job. Never completed...
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Old 08-22-2014, 08:18 PM   #4
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0III0forlife is right about checking if its the valve cover or rear main. I have done 2 4.0l & 1 4.2l rear seals. You do not drop the granny. Need clean space to work. Pull pan and rear main cap. 1 half will be in the lower half of the cap and the other piece is pushed up between the block and crank. This is the only tricky part. If its never been replaced its gonna kind of be stuck. I used a Klein 6"#1 standard screwdriver and 12oz ballpeen to start. Tap firmly until it breaks loose. Takes a little bit of patience but once it starts moving grab the half that starts protruding with needle nose and play the push and pull game. On 1 repair it quit moving half way out. So I took a 16 handdrive framing nail and bent it into a curve an lightly tapped to get it moving. On replacing with new part use OEM MOPAR! The aftermarket seals (we tried 2) were just a tiny bit off and would get the outer portion cut or "trimmed" off by the sharp part of the block. Builders grease (I use Lucas break in grease) and start making sure you use the correct side facing the flywheel with needle nose lighlty pressing into the entrance point. Lube lower half in cap, main bearing and put RTV where the 2 half's meet and torque to spec. Replace oil pan gasket with a rubber coated steel Felpro and you are good for years to come.
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Old 08-22-2014, 09:01 PM   #5
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Hmm... I will have to do some more looking. i ordered in a new oil pan gasket, since that seems to be the obvious source of my leak. But now... I notice that the spark plug sockets have oil in them...

But the above sure looks like a rear main to me.
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Old 08-22-2014, 09:08 PM   #6
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You said the spark plug "sockets" have oil in them. Before you start pulling things apart check the valve cover. There is a chance it could be the valve cover gasket.

You can also clean the engine up, add dye to the oil and try finding the leak that way.
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Old 08-23-2014, 03:53 PM   #7
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my bad,I thought it was a 2.5...russ

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