Overfilling Jeep 4.0L causing rear main seal to leak?

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Joined
Aug 3, 2004
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Indianapolis, IN
Ok, changed the ZJ's oil Tuesday, realized I used the wrong weight Wed and drained it and refilled with the right stuff. I noticed today that there is a huge puddle of fresh oil under the Jeep. The drain plug area is dry, it is all coming from the rear main seal. I didn't drain the filter when I redid the oil, just pulled the plug and drained it, and then put in the full 6 quarts. The dipstick reads over the safe mark by about a half inch. Would the excess oil be blowing out the rear main seal and will it quit with the excess is removed? I have been keeping an eye on the dipstick level to make sure it doesn't leak out a dangerous amount. TIA Edit: Jeep has 86K on it so rear main will need to be replaced soon anyway [Roll Eyes]
 
Joined
Jul 18, 2004
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Location
ATL, GA
Check www.jeepsunlimited.com for better answers. Jeep with 86k doesn't justify rear main seal leak. I own a TJ with 4.0 in it. From my experience with 4.0 when I don't tighten up the filter well enough, it leaks oil and oil makes its way down around the oil pan and then down the rear main seal. I wouldn't expect so much oil leak as you described from rear main. Oh yeah BTW you definitely way overfilled your engine with your filter in place with full of oil in it. Michael K.
 
Joined
Jun 5, 2003
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Apple Valley, California
It's very common for the 4.0 to develop a rear main leak.....Usually well before 80K. It just means that the Jeep is marking it's territory. Do a search at JU and you will see that it's very common. Personally I don't think 1/2 qt of overfill is enough to make it leak. Make sure that the filter is tight and that your not seeing residual oil that ran down the oil pan rail when you removed the old filter. Chris-----> 02 TJ with 27K that leaks oil from everywhere!
 
Joined
Feb 15, 2006
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Location
Socorro, New Mexico
I have a 2004 Jeep Wrangler X and it has 40,000 miles on it. I think the rear main seal is leaking because a little bit of oil drips down between the transmission and the oil pan. To change the rear main seal do I just need to take off the oil pan or do I need to do anything to the transmission?
 
Joined
Sep 28, 2002
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Pottstown, PA
The 4.0 has a two piece seal ..so it can be done without taking out the trans. It's still an acquired skill ..but doable. The 4 banger, from the same engine, has a one piece seal.
 
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