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Replacing your rear main seal |
Unfortunately, a leaky rear main seal is pretty common on the 4.0L motor found in most Jeeps. Getting it fixed at the dealership usually runs in the neighborhood of $500, however, if you’ve got a free afternoon, you can fix it yourself for under $50. But be prepared, as my uncle so aptly put it, this is definitely “one of the oiliest jobs possible on a Jeep.” New rear main seals are usually in stock at most auto parts stores, and seem to range from $13 to $15. At that price, you might go ahead and pick up two of them, just in case you mess up one seal during the install like we did… DOH! It might save you from having to make a trip back to the auto parts store, heh-heh…
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To start with, depending on how much lift you’ve got, you’ll want to jack up the vehicle by the frame, pull the wheels, and let the front axle hang down to give you clearance to get the oil pan out. Once that’s done, remove the starter and the bazillion bolts holding the oil pan to the bottom of the motor. Oh yeah, don’t forget to drain your oil first!
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Now comes the fun part of seperating the pan from the rest of the motor. The XJ we were working on had well over 100,000 miles on it, and had never had the oil pan removed before, so it was a bit stubborn. We had 3 flathead screw drivers and a Stanley “wonder bar” pry bar going around splitting the seal all around the oil pan. It finally popped off after about a half hour of work. To get it out, lower the back half and pull it out under the transmission.
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The oil pan was full of black sludge, so it was probably good we pulled it anyway. In addition, the pick-up for the oil filter was nearly clogged with sludge and crystalized gunk. The old oil pan gasket was rock hard, I’d definitely recommend getting a good gasket scraper, or a chisel! Be sure to remove the front and rear neoprene oil seals, they’re pretty easy to pull out and should come off in one piece. Don’t forge to clean the old gasket material off of the bottom of the block as well. We probably spent more time scraping off old gasket than doing anything else…
The rear main seal is located in the back-most bearing cap. It’ll probably take a large breaker bar or impact wrench to get the bolts loose. The bottom half of the seal is in the bearing cap, and if it’s old like the one we were replacing, it may take some work to get all the old seal out. Clean the bearing cap thoroughly to make sure all the old seal is out..
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The upper half of the seal is actually inside the block itself. It’s somewhat hard to see too, especially when everything’s covered in oil — the yellow arrows point to the holes where the upper half of the seal goes in. In order to get this upper half out, you’ll need to use a punch or sharp tool (we ended up using a small torx driver and a hammer) to push the seal out from one side. Be very careful not to score the crankshaft. The seal has a metal support wire inside it, this is what you’ll be pushing on with the punch to get the seal out.
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Once you get part of the seal coming out the other side, you can grab it with some needle-nose pliers to pull it out the rest of the way. Again, watch that crankshaft…
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With the upper half out, carefully insert the new seal half into one of the holes in the block and push it all the way in. An article on the International Full-size Jeep Association website recommended to “coat the block contacting surface at the upper seal with soap, and the lip of the seal with engine oil,” (refer to diagram above). It may help to put a breaker bar on the harmonic balancer on the front of the engine to manually turn the crankshaft. note: the lip of the seal must face to the front of the engine.
Once the upper half is in, coat both sides of the lower seal half’s end tabs with gasket maker, make sure not to get any sealant on the lip of the seal. Next coat the outer surface of the lower seal with soap and the lip of the seal with engine oil, as you did with the upper half. Press the seal into the bearing cap to seat it firmly. Apply gasket maker to both angled edges of the bearing cap, then replace the bearing cap and torque the bolts to the specified torque.
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The oil pan is actually pretty clean in these photos, compared to what it looked like when we first pulled it out anyway. Once we got a new gasket scraper, we were able to get the rest of the old material off before putting in the new one-piece oil pan gasket. I’d highly recommend getting the one-piece oil pan gasket, it makes like much easier, and only runs about $32. The part number is #53007568.
Now put the oil pan back into place, put all the bolts back in, put the drain plug back in, and fill the engine with oil, and you’re done!
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Thanks for posting your story with pics. I am positive that I can do this now that I had some good pics to look at first.
Thanks for taking the time to take pics along the way and posting this. Great post
Good how-to, but I’ve noticed in all the threads & how-tos I’ve read, no one seems to mention anything about lock-tite. I’ve done 3 rear mains in XJs, and of the 3, two of them were missing at least one pan bolt. It might be worth the extra $6 and 60 seconds to dab some medium-grade thread locker on the pan bolts, oil pump bolts, and valve cover bolts… I know it is to me! :o)
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If I am going to replace the rear main seal, and the clutch/throwout bearing at the same time will this make the removal easier being that the trans will be out of the way?
ill be replacing my buddys rear main seal tonight on his jeep im glad i looked here first cause i was gonna pull the trans lol thanks for the step by step
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I did the same thing on my 95 ZJ years ago. The only difference is I loosened all of the main caps (just a little) to free up the crank and give a little gap. I also replaced the timing chain, balancer and seal and water pump while I had it all apart. Was nice to see no oil underneath. I’ll be doing my 98 XJ next.
Do U Know HowTo Change The Front Main Seal, The One Thats Behind The Harmonic Balancer.. & Do U Have Photo’s Of This Process?
Thx for sharing.
Great help to newbie like myself.
good lookin out on the pics even though my motor was a 5.2 v8 the pics helped me out with 90% of the of job
Tremendous. Many thanks indeed.
Unfortunately, most write-ups and videoes/pictures available appear to deal with the 4L XJ. Mine is 2.5 L TD. I am hoping that there is no difference in the procedure for changing the oil seal.
Well, mine is also a 2,5 and I agree entirely about most of the write-ups referring to the 4L engine.
I regret to say that the informaiton I have obtained so far, points firmly in the direction of a one-piece rear. oil seal on the 2,5L. This means that changing it is a much bigger operation. You might try going up in viscosity as a first step. I will move to a 15-40 SAE semi-synthetic at next change and, if that does not help, a 15-40 SAE mineral oil – like Castrol. If that fails then I guess I will contemplate removing the transmission and getting the job done.
your a life saver oil cost to much to buy every other day
hi all would anyone be able to tell me if its the same process on the cherokee sport 2.5 diesel 1995, as mine went 2 days ago and the garage wont £650 to do it ,but looking at this post a would be able to do it myself,iam also having a trouble with it blowing soot,has any1 got an idea on what it could be its been driving me mad for the last few months,my wife keeps tell me to sell it for parts but its my baby and i dont wont to have to pulled apart so any help would be great thanks all
Well I blew my rear main seal in spectacular fashion, The Jeep drops the oil directly on the exhaust which is a nice warning if your going down the interstate. Not so much if your the poor SOB behind it.
So decided to do some research and see if it was something a mechanically inclined weekend mechanic could do and ran across this post.
I figured that it didnt look that hard to do, however looking at pictures did not prepare me for the joy of having oil drip in my face while using hammer and chisel to get the old gasket off. (wood chisel with soft taps to prevent scratching). However I was able to do it and the Jeep is running great without marking its spot.
One thing I would like to add is that not just clearance for bolts but to drop the oil pan it was necessary to remove starter and jack up engine 1-2 inches by putting board under transmission.
Tahnks for the post and taking times to post pictures.
Rob
Hi,
Agree fully about most write-ups being about 4.0 L engines. There are obviously many more of them. Min is a 2,5 TD Sport. The oil leak on it is not major but irritating. Really the only remaining issue with my 1997 XJ.
After changing my engine, the workshop put in a fully synthetic 05-40 oil. Not a good idea on high-mileage motors. Strange that workshops don’t appreciate this. So now I have a leak. I have progressively moved up the scale with motor oils and am now on a semi-synthetic Castrol 15-50 SAE for high-mileage motors. It is supposed to make seals more supple and thereby stop leaks. Has not had the desired effect after three months. I have now added an oil additive Stop Leak type product and have fingers crossed. If this does not help (doesn’t look very promising after three weeks) then I shall move up to a mineral oil 15-50 (assuming I can find one). I have purchased a new main bearing seal from Mansfield 4×4 Ltd in the UK – just in case. I can keep you posted on progress. For interest, my engine has gone 260,000 kilometers.
Mistake on previous comment. The workshop put in a 05-15 SAE fully synthetic oil.
Jeep service station has been telling me to replace this for about a year. I went today for an estimate and they want $710 and said they have to pull the transmission. It can’t be leaking too badly b/c I have never seen a leak and just went 3500 miles with no issues between oil changes. I think I’m getting raked. I can’t do this work myself, but can someone confirm whether or not they need to pull the transmission on a 2003 Jeep Grand Cherokee? Does it matter if the RMS is a 1-piece or 2-piece? And how will I know?
Would VERY MUCH appreciate any help…can’t pay $710 right now!
You info definitely helped but can’t get the oil pan out, don’t have enough clearance – What now?
Any help would be great the Jeep is in pieces on the garage!!!!
Thanks,
Ray
How would I do the rear main seal on a 1992 jeep Cherokee?
Isn’t the schematic slightly different?
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Try a pint of Auto Trans Stop Leak in the engine oil. Worked for me, swelled up the rubber main seal in about 2 days.