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Discussion Starter #1
I have a 87 YJ(4.2 w/MPI) that developed an oil leak that seemed to progressively get worse. It was leaking from the front of the oil pan and covering the bottome of the jeep. I dropped the oil pan, scrapped what seemed like 10 hours of old gasket material off of the pan(it had blown out in the front) and block. I used a 1 piece rubber gasket because it seemed like that was the best option.
Bolted pan up with new seal, filled with fresh oil. Cranked for about 2 secs a few times to get some oil into the pump before I started it because I figured I had just drained everything out of it. Started fine, had slight whistle(almost like belt squeak) from bottom of motor. Squeak went away after about a minute and leak started.
Leaks HEAVILY at rear pan seal by RMS. I repeated the whole process over again thinking I had mashed the seal by accident, looked perfect when I pulled it off. I bought a brand new gasket and repeated the steps even with a small amount of The Right Stuff on that portion of the pan seal. No squealing but massive oil leak at back of pan.
HELP!
Could I have blown the RMS? How? I can put in a new RMS and oil pan gasket I just dont want to go through the process and find out thats not the problem. Any help is much appreciated.
 

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Welcome to the Forum Ryadboh,

Changing the Rear Main Seal isn't too difficult on a 4.2.
You are already experienced in replacing the pan gasket.
The blue rubber Fel-Pro one piece gasket is the one to use.

When replacing the RMS, I suggest removing the rear cap (obviously) for access to the seal. Then loosen the remaining 6 journal caps. Loose enough so that the caps can drop down a bit.
I bought my RMS at NAPA because, overall, I've had better luck with their parts than some of the other parts stores. I don't remember for sure, but the seal I bought might have been a Fel-Pro seal too.
Make sure that the rear cap is spotlessly clean. I used a wire brush to clean mine.
Oil the seals well and be sure to use the little white plastic "shoehorn" that comes with the seal to help start the upper half between the crankshaft and the block.
Use a small speck of RTV on the sides of the cap, making sure to not get any RTV between surfaces where the block and the cap meet.

Don't forget to tighten the remaining 6 journal caps and torque all of them to spec with a good torque wrench.

Use a dab of RTV on all 4 corners of the pan gasket according to the instructions that come with the Fel-Pro pan gasket.

For a more detailed instruction about the RMS, look for a post by Got it at last. Look in his signature for a link to several service manuals. Click on the link and then click on the manual that most closely relates to your '87. Look in the 4.4 engine section for how to replace the RMS.

BTW, are you sure your leak is coming from the pan area?
It's common for the valve cover to leak at the rear and run down the back of the motor, to look like it's the pan leaking, when in reality, it's the valve cover gasket leaking.

Good Luck, L.M.
 

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Welcome to the Forum Ryadboh,

Changing the Rear Main Seal isn't too difficult on a 4.2.
You are already experienced in replacing the pan gasket.
The blue rubber Fel-Pro one piece gasket is the one to use.

When replacing the RMS, I suggest removing the rear cap (obviously) for access to the seal. Then loosen the remaining 6 journal caps. Loose enough so that the caps can drop down a bit.
I bought my RMS at NAPA because, overall, I've had better luck with their parts than some of the other parts stores. I don't remember for sure, but the seal I bought might have been a Fel-Pro seal too.
Make sure that the rear cap is spotlessly clean. I used a wire brush to clean mine.
Oil the seals well and be sure to use the little white plastic "shoehorn" that comes with the seal to help start the upper half between the crankshaft and the block.
Use a small speck of RTV on the sides of the cap, making sure to not get any RTV between surfaces where the block and the cap meet.

Don't forget to tighten the remaining 6 journal caps and torque all of them to spec with a good torque wrench.

Use a dab of RTV on all 4 corners of the pan gasket according to the instructions that come with the Fel-Pro pan gasket.

For a more detailed instruction about the RMS, look for a post by Got it at last. Look in his signature for a link to several service manuals. Click on the link and then click on the manual that most closely relates to your '87. Look in the 4.4 engine section for how to replace the RMS.

BTW, are you sure your leak is coming from the pan area?
It's common for the valve cover to leak at the rear and run down the back of the motor, to look like it's the pan leaking, when in reality, it's the valve cover gasket leaking.

Good Luck, L.M.
Great info. I'd clean the engine real well and be 100% certain of where the oil is coming from before digging in again. If need be add a UV dye to the oil for oil leak detection, after doing a thorough clean up of all existing leaking oil.

Good luck and :welcome: to the forum.
 

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Discussion Starter #4
Thanks for the info!
When I originally replaced the oil pan seal I heavily cleaned the motor to check for other leaks etc that I could fix at the same time, nada. A buddy of mine that used to fix all of our work trucks for the past 20 years or so is going to look at it and probably do the RMS for me hopefully next week. Both times I have changed the gasket I have used the nice rubber Fel Pro 1 piece kind because I had heard they worked great.
I was working on other things on the jeep and wanted to run it and make sure the leak was still there. Ran perfect, got up to temp quick(its about 115 degrees here right now) and no leak whatsoever, only when I moved it.
It is definitely coming from the back of the pan, I can see it just streaming out of there when the motor is running.
 
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