2018 3.6 JLU Seal Failures - Rear Main Seal failure

  • Thread starter Deleted member 11497
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I purchased my 3.6 JLU new from the dealer 3 years ago and took advantage of the included 3 free oil changes from the dealership express lube service department. This is the first vehicle I have ever owned in which I did not change my own oil. A few months ago I noticed oil spots on my very clean garage floor so I crawled under and noticed that it was dripping from both rubber plugs at the bottom of the bell housing. I scheduled service with tthe dealership and they were 8 weeks out on appointments so I got on the list and waited, during this time I rounded up all of my oil change service records and discovered that the very first oil service record noted an oil quantity of 5 quarts added which is consistent with the owner manual's prescribed amount. I then discovered that all 5 subsequent service records noted 6 quarts, not 5. The owners manual clearly stataes that the capacity is 5 quarts and over or unerfilling will cause engine damage. Once I finally got in for my service appointment last week they diagnosed the 3.6 as having a leak on the rear main, both side valve cover gaskets, and a few other seals related to some sort of sensors or sending units elsewhere on the engine. All of this was covered under the 6/60 powertrain warranty. The dealership declined to comment on the overfill situation and so I suggested that they at least make the express lube department aware but still they declind any comment, so i let it go at that. (I have to take some responsibility on myself for not paying attention to the dealer service records indicating 6qts and / or me not noticing the excessive level on the dipstick, but in my defence I will say that the dipstick is somewhat difficult to read on the shiny metal rod and tiny gauging space making it difficult to see that extra quart on the stick, especially being brand new mostly clear synthetic oil) Unfortunately, before all of this .. I had already pre-paid for a service pack of 3 oil changes at a significantly reduced cost and those are non-refundable. I will be changing my own oil again from now on. So .. would anyone like to make an argument that these seal failures were NOT the result of an overfilled crankcase for 23,000 out of the past 26,000 miles??
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Strommen95

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I won't to pretend to know what caused the failure specifically. My hunch would be it's just defective. I don't know anything about the seals except that they seem to leak a lot. There are a lot of reports of seal failures with the 3.6 in this forum. Probably a ton on Wranglerforum for the 3.6 JK. You'll have a lot of different threads if you search "oil leak" or something similar here. My hunch, which is just an opinion by seeing how common this issue is, is that it's a coincidence. Either way, it's good it was settled during the warranty and not out of it.
 

mwilk012

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It has nothing to do with oil level. At all. 100% guaranteed.
 
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Deleted member 11497

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I did search around the forum a bit before posting and thought I saw a few others with similar overfill leak concerns. I am not a professional mechanic but I am an old guy and have learned a few things over the years. I personally have never known of anyone with serious engine damage resulting from overfilling of oil but only general concerns with optimal circulation of lube throughout the engine etc. The mechanic that officially diagnosed the rear main seal leak commented that "its an extremely rare" condition for this engine especially with such low mileage. Things are different these days with oil filters in the top of the engine and so forth, it may have been wishful thinking on my part in speculating about the overfill causing this so I wouldnt have to believe there would be so many mfg defects showing up all at once. Designing and building an engine that doesnt leak seems like a pretty simple concept, but maybe not. Yes I am thankful for the warranty coverage but not feeling so great about the long term reliability of the 3.6, and I still think the lube techs should know how much oil to use. Thanks for the replies.
 

blnewt

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I've had a rear main leak for about a year now (that I'm aware of), luckily it's just a dribble and hasn't got any worse. Seems like the seal isn't doing a great job with it's primary goal of sealing, too many around here also have this leak. I don't trust our local dealer to do any repairs on my Jeep so I'll just DIY it or arrange to take it out of town during a vacation and have it done then.

Nice that you got it taken care of, hopefully you have a decent mechanic doing your service.
 

Five Seasons

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I have done my own engine oil changes with the correct amount of fluid added. I have a leaking rear main on my JL. It is only one data point but I understand there are others in a similar situation. It is probably just bad luck.
 

blnewt

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I have done my own engine oil changes with the correct amount of fluid added. I have a leaking rear main on my JL. It is only one data point but I understand there are others in a similar situation. It is probably just bad luck.
Yeah, it's just the way the dice roll. Like I said in my post above, mine seems to just get those rubber plugs a bit wet but not to the point of dripping on my garage, it's pretty much been that way for about a year now. TBH I'd rather have just that minor leak that isn't getting worse then take it to the dealer and have something much worse happen. A lot of issues w/ my last trip there :(
 
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