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Rear Main Seal When Replacing Clutch

W

walkngdude

NAXJA Forum User
Location
Santa Cruz California
Hi
I'm doing my clutch, bearing, plate and slave in my 1992 5 speed and I want to replace the rear main while I'm at it.



My question is:
Is it still necessary/preferred/recommended that I remove the oil pan and go at it from the bottom (as this is the only tutorial that I can find on YouTube) or can I do it entirely from behind the flywheel?


I have seen the later method used on other makes of vehicles but not for jeeps.


Thanks
Marc
 
If it ain't broke, don't fix it. If it is not leaking, I would leave it alone.
 
And NO it can only be done by removing the oil pan!
 
Changing the RMS, with the trans out is not easy, what's going to hold the engine up in place, with the trans out and oil pan remove?
These are two separate jobs.
 
Thanks guys.



From watching the videos I thought that it might be impossible to put it in from the back like I had seen on videos for other cars due to the spline on the XJ RMS.


When I called my mechanic for a quote he included the rear main along with a complete clutch job for $1300. He said that they always like to include the RMS when doing a clutch. That sounded reasonable to me considering if it blows it seems like it would soak the entire clutch compartment with oil.


I'm still considering replacing it anyways for reasons I mentioned above. And that I have over 250k on it with lots of oil seeping out around the motor so it's hard to tell where it's all coming from.


How hard is it removing the oil pan? Considering that I have a 3" "Old Man Emu" lift, is it going to be difficult to get it past the steering linkage?



OME Lift:
https://ok4wd.com/old-man-emu-2-suspension-system-for-1984-2001-jeep-cherokee-xj
 
walkngdude said:
When I called my mechanic for a quote he included the rear main along with a complete clutch job for $1300. He said that they always like to include the RMS when doing a clutch.
Click to expand...


Translation - They like to upsell. While it makes sense to do the RMS if you normally have to pull the trans to do it, I'm not sure I'd trust a mechanic who quoted it thinking you have to pulls the trans to do the RMS.


The time I took my Jeep to a mechanic to do the RMS because I had my arm in a sling, he argued that he had to pull the tranny until I showed him the FSM. It leaked worse afterwards and he kept insisting it had to be a clogged PCV valve. I gave up and did it myself 2 months later, only to discovered the idiot only replaced the bottom half of the seal and didn't tighten the oil pan bolts. He also took a chunk out of the block trying to chisel out the upper half before giving up.
 
walkngdude said:
I'm still considering replacing it anyways for reasons I mentioned above. And that I have over 250k on it with lots of oil seeping out around the motor so it's hard to tell where it's all coming from.
How hard is it removing the oil pan? Considering that I have a 3" "Old Man Emu" lift, is it going to be difficult to get it past the steering linkage?
Click to expand...

4.0s seem to leak oil from everywhere. You might try cleaning the engine well and then looking for the source, the rear of the valve cover, is a common spot as well as the oil filter adaptor and the RMS.
You may not actually have RMS leak, more than one person has changed it only to find the leak was coming from the valve cover.

To provide the room to remove the pan, I disconnect the bottom of the front shocks, disconnect the track bar and then jack it as high as the jacks stands allow.
If you have time, drop the pan and let it sit for a couple of days or at least don't start it for a few days before, this helps reduce the rain of oil onto your face.
It's one of my least favorite jobs.
 
The source of confusion regarding removing the trans to do the RMS is on account of the fact that many late model vehicles use a one piece RMS which is accessed from the back of the block. That is not the case with the 4.0. The 4.0 still uses a two piece RMS which requires removal of the rear bearing cap in order to replace. On the plus side, it isn't the rope style.

Dropping the pan with a 3" lift should not be difficult. I did mine a couple of years ago. I removed my starter, but I think that was the biggest complication in getting the pan off. My challenges all came with deciding to take care of the timing cover and front crank seal. That opened a can of worms. There is a "used to be rubber, now is hard brittle plastic" chain dampener inside there which I did not anticipate needing to replace. There is also a need for a tool to properly align the cover when reinstalling. It was all worth doing, but a PITA too.
 
Make sure they replace the pilot bearing in the end of the crank. PO of my Comanche didn't when he did the clutch and when it seized, it took out the input bearing for the transmission.
 
lazyxj said:
Changing the RMS, with the trans out is not easy, what's going to hold the engine up in place, with the trans out and oil pan remove?
These are two separate jobs.
Click to expand...

Stupidest thing I've read in a long time. You do know the engine isn't held up by the oilpan or transmission right? That's what motor mounts are for.
 
lawsoncl said:
Translation - They like to upsell. While it makes sense to do the RMS if you normally have to pull the trans to do it, I'm not sure I'd trust a mechanic who quoted it thinking you have to pulls the trans to do the RMS.


The time I took my Jeep to a mechanic to do the RMS because I had my arm in a sling, he argued that he had to pull the tranny until I showed him the FSM. It leaked worse afterwards and he kept insisting it had to be a clogged PCV valve. I gave up and did it myself 2 months later, only to discovered the idiot only replaced the bottom half of the seal and didn't tighten the oil pan bolts. He also took a chunk out of the block trying to chisel out the upper half before giving up.
Click to expand...

You also have no idea what you are talking about. I have been a mechanic for 27 years. And every single time I pull a transmission out we try to replace the rms. Even if I have to do for parts only. 99% of vehicles you have to drop the transmission to replace. It only makes since to change it when you have the transmission out cause otherwise you'd be repaying all the labor over again. It's kinda standard practice.
 
Replacing the rms as a matter of fact just because you have already pulled the transmission is dumb. Sure if it leaks, and it needs a clutch… sure, now is the best time.

But if I took my jeep in for a clutch, and was met with that kind of bravado about doing The rms, I would be looking for a new shop. Mine isn’t leaking, so go ahead and recommend it based on mileage! See what happens! If you brought up the fact that “mOst cArS cHAnGe tHE RmS frOM tHe tRAnS sIdE!”, I would DEFINATELY be removing the jeep from your service bay!

It is most definately NOT standard practice!
 
Hambone said:
Stupidest thing I've read in a long time. You do know the engine isn't held up by the oilpan or transmission right? That's what motor mounts are for.
Click to expand...

The engine is most definately partially held up by the transmission mount, which would be removed with the trans. After which, the block will rotate on the axis of the motor mounts. Is it a giant deal? Not unless you have stock style motor mounts, but is it possible to cause problems? Yup.
Not saying your post is the stupidest thing I’ve read, but you can definately see the “mechanic vs tech” argument in your posts.
 
Hambone said:
You also have no idea what you are talking about. I have been a mechanic for 27 years. And every single time I pull a transmission out we try to replace the rms. Even if I have to do for parts only. 99% of vehicles you have to drop the transmission to replace. It only makes since to change it when you have the transmission out cause otherwise you'd be repaying all the labor over again. It's kinda standard practice.
Click to expand...


I'm surprised that you've never encountered the Jeep 4.0, or any of the other multitude of engines that use a 2-piece RMS captured in the rear-most block. I can see your confusion if you didn't understand the rms is done by pulling the oil pan. (doesn't excuse the insulting post though)

Normally when pulling the trans, you put a jack under the oil pan to prevent the engine from tipping too much when you remove the rear support provided by the trans and the trans mount. Failure to do so on the Cherokee allows the engine to tip back until the valve cover hits the firewall, and the over rotation can tear the forward engine mounts rubber. If the front mounts are really shot, you can actually hit the radiator with the fan.


You're right though if it's a single piece, then it makes sense to do it while the trans it out. A good shop should recommend proactive things like replacing seals that are accessible during other work.
 
Hambone said:
You also have no idea what you are talking about. I have been a mechanic for 27 years. And every single time I pull a transmission out we try to replace the rms.
Click to expand...

That is precisely why I try to avoid taking any of my vehicles to a professional mechanic.

I have no doubt you are telling the truth.

That kind of upselling just ticks me off.

There is absolutely no reason at all to try to replace the RMS just because you have the transmission out of an XJ. None of the work overlaps. An XJ requires you to remove the oil pan in order to replace the RMS. It is best done with the transmission in place, as was already stated.

But there is good money to be made fleecing the ignorant.
 
It was definitely the ticket on my '96. It was the last thing I re-sealed, but doing that one finally got my engine leak free.

I wonder if the 27yr mechanic has ever done a rope seal. I think it was my Olds 455 that used that style.
 
cruiser54 said:
And besides, they rarely actually leak. It's something up above.
Click to expand...

Mine did. Changing it stopped the leak.

I agree it's wise to properly determine the source before committing to such a messy job.
 
Hambone said:
Stupidest thing I've read in a long time. You do know the engine isn't held up by the oilpan or transmission right? That's what motor mounts are for.
Click to expand...


I think the point here is that in order to get the pan off, it is often necessary to loosen the transmission mount and jack the back of the engine higher. Part of the steering system effectively blocks the pan from dropping and I have found that jacking the transmission up a little creates enough of a gap that I can get the pan to slide out. The motor mounts will hold the engine in place but they are located forward of the balance point of the engine so removing the transmission and bellhousing not only will cause the engine to droop a bit in the back, it gives you very few jacking points to raise the rear of the engine high enough to get the pan to slide out. I am not saying it can't be done but I would agree with the posters who note that removal of the transmission does nothing to help you replace an RMS. It is a completely different job.
 
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