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Rear Main questions....couldnt find a clear answer searching


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Ok, so driving home from work today and hear something dragging. Stop the MJ, look underneath, the plastic shield for the tank has broken and was dragging, not a big deal but....the shield was covered with oil.... the oil leak seems to be coming from the area between the transmission and engine... So I am assuming that the rear main seal has gone down... But here in lies the question..... I read in another post that the valve cover should be cleaned and the the CCV hole should be cleaned as well. If the CCV is not cleaned out, will it blow the rear main again...like within a week, or month, or year.... I will most likely have a shop do the RMS, but the valve cover is something that I can do with out a garage built... that will be soon... so any ideas..... thanks

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Probably wouldn't happen within a week, but a build-up of crankcase pressure can push oil through the rear main seal. It's more of a problem at higher speed/RPM. A couple of trips to the corner store with a light foot on the throttle wouldn't be an issue, a 3-hour drive at 75 MPH on the interstate ... you're pushing your luck.

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I just did a RMS on my '88 because I had a constant drip coming from the bottom of the transmission. A couple things I've learned from doing that job - Get the Fel-Pro double lipped seal as it supposedly works much better than the original seal that Jeep used. While your RMS is most likely junk, you may find (like I did) that the oil filter adapter o-rings are shot and you're leaking oil from there too. I know it might sound crazy that something so far away would wind up dripping oil from your transmission, but I was skeptical until I saw it for myself. The oil finds a path from the oil filter adapter to the starter to the transmission and onto the ground.

 

If you wind up doing it yourself - here are a few tips for the RMS. Loosen all of the main bolts, but do not remove them. Just let the caps hang down a little bit...this will make it very easy for the upper portion of the RMS to slide out. Use the one-piece Fel-Pro oil pan gasket - it's rubber and is a nice design. Don't over torque the oil pan bolts - they only need a few foot pounds. While you're wrenching, might as well replace the oil filter adapter o-rings for good measure (search part number 82560 on NAPA or Advance Auto...it's a kit that comes with more than you need, but it's supposed to have all of the necessary o-rings for our trucks). If you're replacing the valve cover gasket also get the blue Fel-Pro rubber gasket...it'll be the last time you'll need to replace that (be warned, it's expensive!).

 

That's all I can think of for now. I will say that the RMS was a PITA mainly because of the old oil constantly dripping on my head.

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Question... How you install a 1 piece RMS without taking the flywheel off... :hmm:

 

 

Cut it in half and install like a two piece :rotfl2:

hunnt auhhh.... 4real???

 

 

No. there are two pieces seals that are installed top portion then bottom portion, this way you no have to take out the tranny, but the shops will tell you and try to charge you for the tranny removal cause it is the right way but of course they also told me I had a 1 piece RMS as well but they are full of it as I had a 2 piece. But with a 1 piece you have to pull the tranny. :thumbsup:

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Do the valve cover first. I was almost positive my RMS was gone too, but I started with the valve cover (since it was leaking too) and it turned out that my RMS wasnt leaking at all, just the oil running down the back of the engine looked like it was the RMS.

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All the 4.0L engines use a 2-piece seal. The 2.5L uses a 1-piece seal.

 

I don't accept that the "right" way to replace the RMS on a 4.0L is to pull the transmission. I've never known anyone to do that, and there's absolutely no reason to remove the transmission since it doesn't in any way impede access to the seal.

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All the 4.0L engines use a 2-piece seal. The 2.5L uses a 1-piece seal.

 

I don't accept that the "right" way to replace the RMS on a 4.0L is to pull the transmission. I've never known anyone to do that, and there's absolutely no reason to remove the transmission since it doesn't in any way impede access to the seal.

 

 

yeah try to tell that to the shop that quoted me out at 659.63, for an 8 hr job. :rotfl2:

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I know it might sound crazy that something so far away would wind up dripping oil from your transmission, but I was skeptical until I saw it for myself. The oil finds a path from the oil filter adapter to the starter to the transmission and onto the ground.

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this is absolutely true. i've seen valve cover leaks, and oil filter adapter leaks fool people into thinking its rear main seal.

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