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Unread 02-12-2013, 06:39 AM   #1
OldNewJeeper
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Rear Main Seal - How hard is it really?

Hi:

Well I am new to Jeeps. I tried to avoid the temptation but my wife bought me one for Christmas anyway . Here is my question. It checks out great for a 99 with 160K. Now the only issues were a leaking oil pan gasket, a leaking cover gasket and a seeping rear main seal.

Originally I thought I would just change the oil pan gasket but I was told that I might as well replace the rear main seal as well. The oil pan gasket seemed to be fairly easy and within my limited skill set, but I am somewhat concerned about the RMS. You understand that my father and brother are/were gear heads, I missed that gene. Not that I don't understand the technology it is that I just went a different direction. So, here is the question. Is this simply beyond the "first project" and should I just pay the $400 plus materials that I have been quoted.

I really want to learn, but I am afraid I will screw it up and damage the Jeep. I am not a coward but everyone makes it sound SOOOO easy but I keep reading threads about it being done wrong. If it is so easy why do so many people seem to screw it up!

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Unread 02-12-2013, 06:40 AM   #2
OldNewJeeper
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I forgot to say that it is a Cherokee with I6 4.0L HO engine.
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Unread 02-12-2013, 06:59 AM   #3
mayeni
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It is not difficult if you are used to work with engines, I did it on my garage floor on jack stands. My biggest problem was to remove and reinstall the pan, because the front axis does not offer that much space, so it is much easier if you have a lift installed. As a first project at you cherokee it is nice, as a first engine project I think it is a bit hardcore.

http://jeep-xj.info/HowtoRearMain.htm
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Unread 02-12-2013, 08:40 AM   #4
habbyguy
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I agree that 80% of the job is getting the pan off and back on (with the gasket in place). The design of the RMS is a split design, so you have to remove the bearing cap and push out the upper half. I understand that can go wrong, but I didn't find it difficult at all, and the lower half was like falling off a log.

I had all the leaks you did (hey, Jeeps are nothing if not consistent) PLUS a leak around my oil filter housing adapter (the thing that bolts on the side of the motor and holds the filter). I only noticed it when I was doing my RMS. Now my driveway is dry at long last.
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Unread 02-12-2013, 08:51 AM   #5
Jason, aka: Jeepin.com
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It's it a job for sure, but not really all that bad. Set aside a whole day just in case, have a spare RMS on hand (they're inexpensive) in case you mess one up during the install. Get a 1-pc oil pan gasket, and have a buddy around to help out. You'll want to have a set of tall jack stands and a good floor jack. I use 6-ton jack stands for their height -- if you don't get the vehicle up high enough, you'll have trouble getting the oil pan out.

http://jeepin.com/features/rearmain
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Unread 02-12-2013, 11:41 AM   #6
OldNewJeeper
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Thanks for the help.

Perhaps I am being a bit of a puss. You see my family are hardcore gear heads, my dad worked as a crew chief at Indy for two years and my brother rebuild his Camaro from the ground up in order to get his learners permit. He was known to pull the engine and trans just to clean and paint it. I simply did not get into all that. I am inherently lazy and doing things just to do them seems silly! I already have the pan and RMS (2) with the double seal. I have some lower 3 ton units and lower jack but I will buy some new stuff.

Again thanks for the help. Normally I would have gone for the valve cover, then tried the pan, but since the RMS is right there is seemed a good idea to try.

Keep the advice coming. Mine is 4x4 the YouTube vid is 2x4. I would guess I will loose some work space because of that, am I right? I have not had it up in the garage because the wife does not want the oil on the floor. We all must keep our wives happy or nobody is happy
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Unread 02-12-2013, 12:12 PM   #7
habbyguy
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I agree it would be madness to do the pan gasket without changing the RMS. It's really one of the easier parts of the job.

FWIW, I was able to get my pan out without dropping any suspension pieces, but JUST barely, and that's with 3" of lift and some wiggling, grunting and groaning. Still, it was SO much easier than dropping the pan on my Alfa Romeo Spider that it almost seemed like a pleasure!
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Unread 02-12-2013, 01:30 PM   #8
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Tricks are spray glue, a 3/16" brass punch. Once the bearing cap is off use the brass punch (maybe in a 1/2" or 3/8" extension) to break the upper rear main free, fish it out, clean with some penetrating oil, dip the new upper half in some fresh oil and make sure it goes back in the right way (so the flap is pointed correctly, see lower part) , fish it back in carefully so as to not peel bits of it off on the sharp block edge. Clean up the pan and block areas for the gasket, use a dab of RTV in the places the main bearing cap meets the block on eitherside and where the timing cover meets the block on either side, use a little spray glue on the top of the gasket and block, stick the gasket to the block so it holds it in place, and put it back together.
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Unread 02-12-2013, 02:06 PM   #9
OldNewJeeper
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This seems like a good time to inspect the timing chain. Is it? If so, any good references on how to do that?
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Unread 02-12-2013, 03:22 PM   #10
dman27
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Hello,
If you read my thread I just did mine a week ago and scratched the crank shaft. Now I'm screwed! I would take it to a shop and make it someone else's problem
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Unread 02-12-2013, 03:30 PM   #11
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I would do the RMS last, not first. Here's why:




I'd be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.

Everybody, who doesn't own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking.

Many mechanics, friends, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?

A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don't jump on the RMS/oil pan gasket bandwagon right off the bat.

Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons.

First off, the engine sits nose-up and any oil will run back to the RMS area. Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber's adage apply here. "***** flows downhill".

Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first.

Revised 9-15-2012
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Unread 02-12-2013, 04:18 PM   #12
OldNewJeeper
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It was a pre-sale Jeep mechanic who gave the the diagnosis but I will get it confirmed. No reason to do the replacement if it does not need it! Thanks for all the advice. Scratching the crank seems to be a common "oh ****" with this. I am somewhat concerned about finding a good mechanic who has done it before. One sure way is to ask how they would do the replacement, if they say "pull the engine" I have a good idea they have never done it.

Thanks for your help. I sure don't want to screw up my wife's biggest Christmas present. That would hurt for a VERY long time.
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Unread 02-12-2013, 04:31 PM   #13
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Quote:
Originally Posted by OldNewJeeper View Post
It was a pre-sale Jeep mechanic who gave the the diagnosis but I will get it confirmed. No reason to do the replacement if it does not need it! Thanks for all the advice. Scratching the crank seems to be a common "oh ****" with this. I am somewhat concerned about finding a good mechanic who has done it before. One sure way is to ask how they would do the replacement, if they say "pull the engine" I have a good idea they have never done it.

Thanks for your help. I sure don't want to screw up my wife's biggest Christmas present. That would hurt for a VERY long time.
YOU are completely qualified to diagnose the leak.
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Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
My Jeep Technical Photos

http://www.cherokeeforum.com/g/album/1725214
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Unread 02-12-2013, 05:02 PM   #14
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Quote:
Originally Posted by dman27 View Post
Hello,
If you read my thread I just did mine a week ago and scratched the crank shaft. Now I'm screwed! I would take it to a shop and make it someone else's problem
This is why you use a brass punch to break it free. Brass is softer than steel. In your case is the damage so bad you can't rotate the crank and lightly sand with emery cloth?
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Unread 02-13-2013, 08:00 AM   #15
habbyguy
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I agree that it's a good idea to look for other sources of the oil leak. My own XJ had all four of the common leaks - head cover gasket, oil filter adapter O-rings, oil pan gasket, and RMS. I guess it wouldn't be possible to say with absolute certainty that the RMS was leaking, but my XJ had nearly 200,000 miles on it at that point, and it only added a tiny bit of work above changing the oil pan gasket. Yes, you do need to be careful to not scratch the crank journal, but it really isn't brain surgery... use a bit of care and it'll be fine. I would recommend using a torque wrench for the job, of course ($10 at Harbor Freight if you don't already have one), but other than that I'd put the actual RMS replacement (leaving out the oil pan gasket part of the job) at a 2/10 difficulty.
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