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…

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!

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.

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..

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.

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…

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.

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!

33 comments

33 Comments so far

  1. Timothy G. Hudson July 10th, 2010 7:06 pm

    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.

  2. Troy July 18th, 2010 5:01 pm

    Thanks for taking the time to take pics along the way and posting this. Great post

  3. Paul July 19th, 2010 2:26 pm

    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)

  4. rear main seal? - JeepForum.com September 16th, 2010 8:02 pm

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  5. Mossman September 26th, 2010 4:52 pm

    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?

  6. joe lee October 26th, 2010 12:39 pm

    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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  11. Chad Warkentin December 28th, 2010 2:16 pm

    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.

  12. ken January 11th, 2011 12:02 pm

    Do U Know HowTo Change The Front Main Seal, The One Thats Behind The Harmonic Balancer.. & Do U Have Photo’s Of This Process?

  13. Botakbeng January 23rd, 2011 4:42 pm

    Thx for sharing.
    Great help to newbie like myself.

  14. tony February 7th, 2011 2:17 pm

    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

  15. Sam March 4th, 2011 12:40 pm

    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.

  16. Sam March 8th, 2011 3:49 pm

    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.

  17. matt March 31st, 2011 12:04 pm

    your a life saver oil cost to much to buy every other day

  18. tev May 9th, 2011 8:37 am

    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

  19. Rob Irwin June 7th, 2011 3:45 pm

    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

  20. Sam August 27th, 2011 12:48 am

    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.

  21. Sam August 27th, 2011 12:49 am

    Mistake on previous comment. The workshop put in a 05-15 SAE fully synthetic oil.

  22. Jennifer August 30th, 2011 8:13 am

    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!

  23. RADoherty October 1st, 2011 8:20 pm

    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

  24. Jacob November 18th, 2011 2:26 pm

    How would I do the rear main seal on a 1992 jeep Cherokee?
    Isn’t the schematic slightly different?

  25. My New 75 CJ5 - Page 2 - Jeep-CJ Forums December 13th, 2011 6:16 pm

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  26. Alfred January 8th, 2012 8:55 pm

    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.

  27. Chlee February 20th, 2012 10:51 am

    For my 92 Sport (2WD and zero lift), in order to get the pan out I had to unbolt the shocks at the bottom, remove the oil pump (to me was easier than just the screen), and cut the exhaust pipe pre-cat in order to drop it after the Y. How anyone else does this without all this work is beyond me, drove me nuts!. Both pieces of the seal were as hard as rock after 106k miles. Used a nail punch on the upper piece to start the process of removing until could use the pliers, insuring I placed it on the wire contained within the seal before striking. The comment to use the breaker bar on the balancer when installing is gold. Used the nail punch on the last quarter inch. If possible, degrease/power wash the entire area before starting this project, it’s messy.

  28. Sam March 7th, 2012 6:39 am

    Hi,

    Mine is a 2,5 TDI 1997 with 250,000 kms on the clock and my experience is exactly the same – workshops just fill up with a high viscosity 05-15 fully synthetic and then the troubles start. Why does no one tell them. We all know. Right?
    Thanks for the tip about the auto trans stop leak. This will be my last chance before having to change the seal. I am already on a 15-50 mineral oil with Castrol Stop Leak additive, and the leak just keeps on.

  29. Steve in Toronto April 16th, 2012 12:03 pm

    ***WARNING!!!!-INSTALL PAN GASKET TO BLOCK WITH ADHESIVE AND A FEW BOLTS PLACED AROUND TO KEEP GASKET FROM FALLING ONLY!!****
    It took me 3 gaskets -jugs of oil on the driveway(what a mess)and allot of four letter words!!!!to finally realize that it could not be done with the gasket on the pan.The back “U” would not seat right and would get pinched when putting the pan up(THIS IS NOT EASY WHEN YOU ARE LAYING ON THE GROUND BY YOURSELF!!)The back of the gasket at the seal side would not seat right and after the 4th attempt poured out of the back of the engine after starting her up.There was no other way!!
    To keep this long and sad story short.
    I will think twice before I go to change my rear seal on my 95 Cherokee Sport.I still have nightmares to this day and it will forever haunt me for the rest of my life.
    Did I mention about removing the sump from the pump in order for the pan to clear there as well????I jacked mine from the frame-Dropped the axle as far as it would go–and still there was no room for that sucker to come out-so while you balance the pan on your chest -you will have to remove the sump from the pump and remember that it only goes one way on and off.Then I was able to maneuver the pan out of my @#$%&^ way!!.
    If I did something wrong -PLEASE let me know!!!–if not —LET THIS BE A WARNING TO YOU BEFORE YOU CHANGE THE REAR SEAL ON A CHEROKEE 4.0L-GOOD LUCK!!

  30. Deb July 31st, 2012 1:50 pm

    Hello, mechanics. I am feeling taken now. The dealership told me it would be about $915 plus tax, for the rear main seal and oil pan replacement. Yet, I took it in for jumping out of first gear. It felt like someone hits you when this happens. Its happened a dozen times periodically and I have just starting using 2nd gear. Do they have to look at the rear main seal to look at the clutch or a pressure plate, or something that has to do with gear shifting?

    Thanks for your help!

    Sincerely,
    Deb

  31. bbyddyof2 December 17th, 2012 10:00 pm

    How do i remove the starter? i really have no idea how to work on anything and this is a project car that i really would love to start working on.

  32. rob November 21st, 2013 3:51 pm

    I replaced my rear main seal on 2003 tj and was feeling good about it till this morning and noticed more oil than ever under the jeep?? I did put sealer on both side of gasket but did not put drops of sealer on the ends of the gasket by the seal. I need a good visual on the rv sealer and where to apply…..Thanks in advance

  33. [...] lasts a long time. If anyone wants additional information, I followed this writeup as a guide. http://jeepin.com/features/rearmain __________________ 2006 Solar Yellow LJ Rubicon Stock Rubicon Drive train / Zone [...]

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