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Old 01-05-2011, 10:48 PM   #1
Join Date: Sep 2010
Location: Wahiawa, HI
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Rear main seal replacement

Looking to replace the rear main seal on my '88 yj. Engine is a stock I6 4.2l. Looking for any help I can get. Have a Chiltons that I will be referencing but it looks unpleasant. Instructions in the Chiltons are as follows
This seal is a two piece neoprene type with a single lip.
1. Raise and support the vehicle on jackstands. (probably going to put it on a lift).
2. Remove the oil pan.
3. Remove the rear main bearing cap and discard the lower seal.
4. Using a center punch, carefully drive the upper half of the seal out of the block just far enough to grab with pliers and pull out.
5. Remove the oil pan front and rear seals and the side gaskets.
To Install:
6. Clean all gasket surfaces.
7. Wipe clean the sealing surface of the crankshaft and coat it lightly with engine oil.
8. Coat the lip of the upper seal with engine oil and install it in the block. The lip faces forward.
9. Place the lower half of the seal into the bearing cap.
10. Coat the outer curved surface of the seal with liquid soap. Coat the seal lip with engine oil.
11. Install the lower seal into the cap, pressing firmly. Be sure the seal is flush with the cylinder block pan rail.
12. Apply loctite 515 or equivalent to the rear bearing cap. The bead should be 3.0mm thick.

Now I don't know how to remove the oil pan or rear main bearing cap. Guessing I have to drain it first then pull it. If anyone has done this and has any tips or anything that would help I would greatly appreciate it.

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Old 01-06-2011, 12:22 AM   #2
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Try this link. I used it when I changed the seal in my 93 with a 4.0. The engines are basically the same. Good luck.

Jeep TJ Wrangler Rubicon 4.0L Oil Pan, Rear Main Bearing Seal Install | SavageSunJeep | SavageSun Engineering


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Old 04-04-2013, 05:41 PM   #3
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That is a good link. Make sure you take your time and be particular about cleaning the surface of your oil pan and block so that the gasket seals properly. The torque specs must be followed when you put it back together or you are asking for problems.
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Old 04-04-2013, 06:03 PM   #4
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I recomend dropping the oil pan the day before you change the seal, that way you dont have as much oil dripping in your face wile youre under it.

I've also heard of lubing the top part of the new seal with dish soap to make it slide in.
4.0 power tech>32RH>231j>4:10>35" MT's
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Old 04-04-2013, 08:23 PM   #5
Join Date: Feb 2013
Location: York, PA
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I put a thin plastic shim, say .003" thick, in between the top half of the seal and the sharp engine block when sliding the upper half through the block to avoid cutting the seal. I did that before and it leaked bad soon after putting it together.
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Old 04-04-2013, 10:21 PM   #6
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There's a great video on youtube if you google it. Yes to the dish soap and the video shows how to cut a plastic drinking straw at an angle to use as a guide when feeding the upper part of the seal into it's channel. Try this link:
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Old 04-04-2013, 10:23 PM   #7
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Just realized we're responding to a question asked 2 years ago. duh.
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Old 04-04-2013, 10:38 PM   #8
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haha, didnt even notice that. O well, this topic should have a sticky as common as it is in YJs
4.0 power tech>32RH>231j>4:10>35" MT's
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Old 10-02-2013, 03:29 PM   #9
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Location: Fort Hood/ BCS, TX
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My question is, why does the parts store ask if its 1 piece or 2 piece if most of the ones I am seeing are 2 piece?

What year 4.2L came with 1 pieces?

Trying to find out before I order a seal and drop it all out tomorrow to find out I actually have a 1 piece seal and have to drop the trans and everything instead.

MY1990 "Little YJ" Build:
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