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Rear main seal leak

Tiny
CHIPPER4EVER
  • MEMBER
  • 1985 JEEP CJ7
  • 4.2L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 105,000 MILES
Please help CJ medevac. Okay, so, the only reason I am asking this question is because I had issues on my 4.0 Cherokee rear main seal it was melted in. But anyhow. I have my 1985 jeep cj7 motor 4.2l and it had a small leak from the rear main seal until I replaced the valve cover gasket. Now it is a big leak more than both leaks combined before which was 1 quart. Every 200 miles now I get 75 miles to 1 quart. I am looking for in your opinion the best gasket or the oil pan and the rear main seal. And any tips you may have like desired tools that make life easier on this one. And anything else you would like to add as well would be greatly appreciated.
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Thursday, January 2nd, 2020 AT 3:35 AM

15 Replies

Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,005 POSTS
I was just told that you pulled into the garage.

I need a little time to get to your rear main and oil pan gasket.

Check this valve cover answer out and let me know if you can do it.

https://www.2carpros.com/questions/cj-medivac-please-help-42l-1985-jeep-cj7-valve-cover-gasket-leak

We'll jump on the rear main next.

The Medic
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Thursday, January 2nd, 2020 AT 4:45 PM
Tiny
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Okay, I am patiently awaiting your reply. And thank you again.
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Friday, January 3rd, 2020 AT 4:29 AM
Tiny
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Also the valve cover gasket has been changed and no longer leaks. Your instructions there were flawless. I do not know if I was clear on that. I just had 2 pre existing cracks in the valve cover but that was also resolved. At least for now.
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Friday, January 3rd, 2020 AT 11:49 AM
Tiny
CJ MEDEVAC
  • MECHANIC
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This is going to give you the info and keep my typing down (I'm pretty slow!).

At the bottom of answers is the "date and time" (It would be nice if it were at the beginning)

This whole post is full of info. This is page one below

If you are going into the pan, let's think about a high volume oil pump while we are in there. They really make an engine last longer!

See MONDAY, SEPTEMBER 8TH, 2014 AT 4:50 PM

at this link.

https://www.2carpros.com/questions/1978-jeep-cj5-engine-wont-start

Here's the deal all about the rear main seal!

Go to:

THURSDAY, SEPTEMBER 18TH, 2014 AT 8:22 PM

at this link.

https://www.2carpros.com/questions/1978-jeep-cj5-engine-wont-start/page/2

The next few answers past that deal with the oil pan gasket!

Since that post, I was able to get a couple of pics of this new type gasket!

It's so neat! It's all one piece, unlike the original 4 piece (2 rubber ends and 2 cork strips)

It goes on so much faster and neater.

Four studs temporarily replace the four larger pan bolts.

The gasket "pops" over these 4 studs, then the pan itself pops over them.

Everything is held perfectly in place while the smaller pan bolts are installed.

Then the 4 plastic studs are removed and the 4 larger bolts are re-installed.

You are done!

Two new pics below.

Like I said, the whole post I linked you to is very informative, but I have steered you more towards what you originally asked for.

Let me know if you need more info, and how you are progressing.

A pic of your Jeep would be nice on your post!

The Medic
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Friday, January 3rd, 2020 AT 9:21 PM
Tiny
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Okay, so all of that reading aside which was informative but long. I got the part number for the oil pan gasket but I did not see one for the rear main seal or the oil pump. I have found a few on my own but I want to be sure to get the best. I do not want junk installed on my jeep. And a lot of these box stores sell junk. Not to mention I know the rear main is a 2 piece and advanced has a one piece listed.
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Saturday, January 4th, 2020 AT 2:25 PM
Tiny
CJ MEDEVAC
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Here's 2 rear mains from AutoZone.

Typing is wrong on the 2nd one (this same one is also available at "Amazon") This one is praised more than black rubber one.

I thought I had posted this last one already- seems you have seen it.

The oil pump will come with a gasket.

Are you considering the high volume oil pump?

Have you found one?

The Medic
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Saturday, January 4th, 2020 AT 4:04 PM
Tiny
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Yes, I am considering a high volume oil pump. This is my daily driver now so it needs to last. Picture for viewing pleasure and for those that will eventually read this and look at the photo and say this is not an 85 cj7 it is a yj well you are only half right. The body is the only yj about this Jeep.
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Sunday, January 5th, 2020 AT 10:05 PM
Tiny
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Also, I forgot to say thank you for your help yet again.
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Sunday, January 5th, 2020 AT 10:08 PM
Tiny
CJ MEDEVAC
  • MECHANIC
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Glad to help!

Thanks for the pic, you have done a super job making it look good!

All you have to do now is keep fixing, let us know where you find any hardships or a better way or more assistance.

Keep the updates coming till it's finished.

The Medic
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Monday, January 6th, 2020 AT 2:32 PM
Tiny
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Well this is going to be it for a while I have to save up some cash to get this thing done. Unfortunately I do not get paid what I once did.
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Tuesday, January 7th, 2020 AT 4:26 AM
Tiny
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So after some time for my engine to stop dropping all the left over oil all over and 1 week has passed since I have put oil in it is still full and I have been parking it in fresh snow and no oil leak. Look at me saving money. Haha however I do have at least one more issue to resolve and that is the ball joints on the passenger front.
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Wednesday, January 8th, 2020 AT 4:28 AM
Tiny
KEN L
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I'm glad you got the oil leak fixed up, for the ball joint issue. Please post your new question here, you must be logged in:

https://www.2carpros.com/questions/new

Cheers, Ken
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Friday, January 10th, 2020 AT 10:58 AM
Tiny
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Well, I already posted a new question about that and CJ medivac basically told me to take it to the shop for that one since I will need an alignment as well. Thank you though.
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Friday, January 10th, 2020 AT 5:44 PM
Tiny
BAS6366
  • MEMBER
  • 1 POST
  • 1985 JEEP CJ7
  • 6 CYL
  • 4WD
  • MANUAL
  • 90,000 MILES
My 1985 cj7 mileage 90,000
has a rear main oil seal leak that is getting worse, how involved is the repair and do you have a rough idea how much I should expect to pay to have it fixed?

Thanks
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Saturday, January 11th, 2020 AT 2:25 PM (Merged)
Tiny
AIRSOFTSOLDRECN9
  • MEMBER
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The rear main seal is a one piece seal on the back of the crankshaft, behind the flywheel. You have to take the transmission out to do this and you might have to drop the oil pan too; however, you should be able to take off and put the seal on without too much trouble. It can take an afternoon or 2 days depending on help and tools. You need extensions and universal joints to get the bell housing bolts off. You need at least a half ton jack and a half inch breaker bar to get the bolts off the flywheel. You need to disengage the slave cylinder to the clutch and then buy a mouting tool to align the spline and the clutch correctly when putting the transmission on. Check the freeze plug on the camshaft and any on the oil gallery as they can leak and make the vehicle appear to have a rear main seal leak. The seal is a 25 dollar item. Now if you want somebody else to do it for you then you need to realize they may charge you 20+ hours in shop time which can make this repair from $400-900. One thing about the seal, don't force it in place or you will damage it then well all your hard work will be for nothing. Take your time putting it in. Find a chilton manual if you can at your parts store it has a good walkthough.
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Saturday, January 11th, 2020 AT 2:25 PM (Merged)

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