Changing rear main seal. Advice?

I'm about to start working on changing my rear main seal and oil pan gasket on my 97 4.0L and I was wondering if there is any advice y'all could give me for doing this. My Jeep is lifted 3.5" inches so it's not gonna be too tight in there and that splash mat was removed long time ago. I did remove the front factory skid to make things easier. Is there anything else I should know?

This forum is full of useful information for changing the RMS and I would be surprised if anyone could add anything new to what has already been posted. Here's what I would do:

1) Search, locate, print, and follow RMS installation techniques from this forum.

2) Buy quality seals, gaskets, and RTV.

3) Use utmost care to avoid scratching the upper bearing cap during upper seal removal.

4) Remove all old gasket or sealant from oil pan or lower bearing cap with appropriate devices.

5) Don't damage the lower bearing cap when clearning.

6) Loosen all bearing caps during upper seal installation.

7) Torque all bearing caps properly during installation.

8) Use rubber bands to hold the oil pan gasket in place during re-assembly.

9) Avoid over torquing the oil pan gasket.

10) It probably wasn't your RMS. Check your oil filter adapter (OFA) o-rings for leakage.

11) Get your name in red and start reaping the benefits of a paid member.

I've been told the easiest way to remove an oil pan is to lift the Jeep from the frame and let the suspension sag. - then remove a tie rod and that will give you enough clearance to slide the pan out. I guess the Haynes manual tells you a way more complicated task. then again, with your 3.5 inch lift you may not need this advice. lol

Depending on mileage you might want to consider installing a new High Volume oil pump.

I tried searching but nothing was very exact or maybe I am just not good at searching. I am hoping my lift gives me enough clearance to get the pan down. The valve cover gasket was replaced back in December. The OFA housing o-rings were replaced a few years ago and before that the oil pan gasket and rear main seal had been replaced but that was a couple years before. The Jeep has about 190,000 miles now and the rear main seal was first replaced just a little less than 100,000 miles. I know how many different leaks look like the rear main seal but I checked those too and the oil is def coming from the rear main seal as well as leaking from around the pan in various places. I figured even if it is just the pan leaking right there and not the rear main seal then might as well go ahead and replace it while I am in there.

like joe said do your oil pump while you got the pan out im kicking myself for not doing it when i did my RMS

I'll throw in another one for the oil pump, and add to check the timing chain tension. Mine was sloppy as hell. Replacing it really smoothed up my idle. If you go for the HV oil pump, use your original pick up; the one included doesn't fit.

nblanton said:

I'll throw in another one for the oil pump, and add to check the timing chain tension. Mine was sloppy as hell. Replacing it really smoothed up my idle. If you go for the HV oil pump, use your original pick up; the one included doesn't fit.

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How do I check the chain tension?

Ok so I have that wonderful bearing cap brace that runs along connecting all the bearing caps. Is there a torque spec for the bolts that hold that on? If so, what is it?

What should I torque the main bearing cap bolts to?

I wish I could afford to buy a new oil pump but I could just barely scrap together the money to do this. I know not an expensive job but I am a broke college student so I am just trying to get my Jeep to survive the rest of college til I get out and can buy something new for daily driving and retire the Jeep from its daily driving days and live the rest of its days as my big boy toy. Maybe even give it to the son or daughter that I may or may not have when they turn 16 if I still got it.

Also should I use any RTV for this? If so, then where?

nblanton said:

If you go for the HV oil pump, use your original pick up; the one included doesn't fit.

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How so?

It's about a 1/4" too long. So the pan won't fit up snug to the block and you will end up with leaks. I wish I would have taken pictures of them side by side when I did mine last month. There are no other differences between the two pickups. They have the same diameter tubing and the bracing is in the same location. Also, the pump is the same dimensions as the standard volume one, except that the body of the pump is longer to allow for the longer rotors. If you look around on the forums, you will see people mention beating the sump of the oil pans out to fit the new pickup. I just used the old one, as it is otherwise correct. The pump I purchased was the Melling HV pump. There may be other manufacturers, and they may be different.

As for the timing chain, when you get the pan completely off reach up into the timing cover from the main gallery. You will be able to see the chain and should be able to reach it with your finger. It will let you know if it is sloppy or not. There should be only about 1/4" or so play either way in a new chain. Mine had about 3/4" slop to either side.

RTV needs to be used at the corners of the gasket where it goes over the #7 bearing cap (the one with the RMS) and I use a bit where the timing cover meets up with the block.

The mains should be torqued to 80 ft-lbs. I'm pretty sure there is a sequence, but I didn't look it up. I just used my Navy mechanic training and did a three step torque sequence, working from the inside out.

I'm also a poor college student, and I would say that is even more reason to fix everything when you can. It's an extra $100 for the chain and pump. The benefit is that you know everything is good down there.

nblanton said:

It's about a 1/4" too long. So the pan won't fit up snug to the block and you will end up with leaks. I wish I would have taken pictures of them side by side when I did mine last month. There are no other differences between the two pickups. They have the same diameter tubing and the bracing is in the same location. Also, the pump is the same dimensions as the standard volume one, except that the body of the pump is longer to allow for the longer rotors. If you look around on the forums, you will see people mention beating the sump of the oil pans out to fit the new pickup. I just used the old one, as it is otherwise correct. The pump I purchased was the Melling HV pump. There may be other manufacturers, and they may be different.

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The pickups are the same. Maybe yours was defective in some way, or not indexed correctly. The reason people beat the pan is to make clearance for the oil pump itself, not the pickup.

You shouldn't use a pickup once it has been removed from a pump.

Really? The threads I read were talking about the pickup hitting the sump. The pump isn't that much different from the original (I wish I had taken measurements and pics of all of it now).

As for not reusing the pickup, if it has a tight fit I couldn't see why there would be an issue. If it were loose, I would have brazed it. In my case, the old pickup was tighter fitting into the cast iron HV body than was the new one it came with. I would have done that way before I would stick something in my engine that requires me to beat the devil out of the sheet metal pan. It would seem to me to much worse to beat on a pan up near the sealing surface if the pump body didn't fit than down in the sump.

Are there that many differences in the pans between model years? Like I said, the only difference between the pump I pulled out (OEM cast aluminum body) and the Melling HV was the rotor housing is about 1/4" longer. The pickup was also a 1/4" longer. I couldn't understand that at all, as the mount point for the pickup tube into the pump is in the same location with respect to the mating surface on the block.

http://www.angelfire.com/my/fan/HVOP.html Illustrates where to dent

I would have done that way before I would stick something in my engine that requires me to beat the devil out of the sheet metal pan.

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The pump is about 1/4" longer. You need to put a few dents in the pan to clearance it, which isn't near the sealing flange. There is no harm in putting any dents in the oil pan or valve cover. Mine has several so that the main girdle will clear with the spacers for the 258 crank. My valve cover also has a few small dents so the Mopar performance springs will clear. Its just sheet metal.

Are there that many differences in the pans between model years? Like I said, the only difference between the pump I pulled out (OEM cast aluminum body) and the Melling HV was the rotor housing is about 1/4" longer. The pickup was also a 1/4" longer.

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No difference in the pans for the 4.0L that I know of. There are a few different pans used on the 258, and I know that the 4.0L pickup won't work with a 258 pan. Are you sure you don't have a 258 pan? Other than that you may have had a bad pickup.

No, I have a bone stock 1995 4.0L. When I took the pan off last month it was the first anyone had been in the bottom end since it left the factory. There wasn't any issues with the pump body not clearing. The only thing was the pickup not letting the pan mate up to the block. I really wish I wasn't in a hurry when I did everything and took pics of everything side by side. I still have the new pickup and the old pump though. If someone wants them to compare to a HV pump and oem pickup I'd be willing to ship for comparison and forum knowledge, as I know a lot of folks swap in the HV pump and have problems with fitment.

There is no need for you to ship anything. I have both here. No difference.

In the pumps, pickups, or both? I'm just curious about it now. Also, what year did the 4.0L get the crank girdle?

The HV pump is about 1/4" longer with countersunk screws. No difference in the pickups. Main girdle was added in 1996, supposedly after weight was removed from the block.

That pump sounds different from the Melling one I got. The bosses for the bolts were flush and in the same spot.

Well got it all done. It went great for the most part except getting the pan back in with the new gasket. I ended up using the zip tie method to hold it in place. I haven't noticed any problems yet so fingers crossed it stays that way.

Now I had to take a picture of this to show off my good maintenance habits that my Dad (who is not a car guy at all) makes fun of my for and says I am wasting my time.



Now you may look at this and think at first "man you did a pretty good job cleaning out that oil pan" but oh no there was no cleaning of the pan. This is when I first pulled the pan. Not one bit of sludge and that is a 13 year old engine with 190,000 original miles on it. I also looked at the bottom end and it was sludge free and the cylinder walls that I could see up in looked spotless. I am damn proud of that since so many people around me think I am obsessive about changing oil and other fluids.

Thanks again for all the help.

nblanton said:

That pump sounds different from the Melling one I got. The bosses for the bolts were flush and in the same spot.

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Who said anything about the bosses being different? :dunno:

Oil pan looks good. What oil have you been using?