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2018 3.6 JLU Seal Failures - Rear Main Seal failure

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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.
 

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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.
 

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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.
 

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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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Just out of curiosity, have you confirmed it is not the oil cooler? It is coming through the plugs, or is it wet above them on the housing? I ask because the plastic oil cooler on these is known to leak and the way the oil runs down the rear of the engine, it is commonly misdiagnosed as a rear seal or valve cover gasket leak.

Not doubting your diagnosis, I am aware of other things that lead to such conclusions with technicians.

The cooler is in the V of the engine and even small amounts of oil leaking look like the rear seal is shot. The engine tilts to the rear and the oil naturally drains down the back side of the block.

This can be confusing, though. From what I have read, one clue is the amount of oil, a rear seal lets a pretty good amount of oil out and a cooler is a slower, more controlled leak, like you are describing.

I am not 100% on that though. I would think a rear seal would leak less as it is not under the same pressure as a cooler and there is a slinger in there. At the same time, the higher pressure in the cooler would force more oil out. That is what is intuitive about it.

Over filling could cause main seal failures, but it is really rare with modern crank case ventilation. Usually, the warning about over filling is because the oil can be whipped up into a foam, causing the oil thickness to be degraded, leading to really poor lubrication and blow by, which can foul converters. Both of which tend to be pretty catastrophic.
 

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Mine is coming through the rubber plugs, still leaking the same too, just a dribble :)
 

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My Ram 2013 Ram3500HD with a big dollar CTD had the same over fill issue. 11 qts filled it but dealer put 12 qt's :whatsgoingon: I never went back even though 3 was free. My JLR had the same Bull shit.
 

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Just out of curiosity, have you confirmed it is not the oil cooler? It is coming through the plugs, or is it wet above them on the housing? I ask because the plastic oil cooler on these is known to leak and the way the oil runs down the rear of the engine, it is commonly misdiagnosed as a rear seal or valve cover gasket leak.

Not doubting your diagnosis, I am aware of other things that lead to such conclusions with technicians.

The cooler is in the V of the engine and even small amounts of oil leaking look like the rear seal is shot. The engine tilts to the rear and the oil naturally drains down the back side of the block.

This can be confusing, though. From what I have read, one clue is the amount of oil, a rear seal lets a pretty good amount of oil out and a cooler is a slower, more controlled leak, like you are describing.

I am not 100% on that though. I would think a rear seal would leak less as it is not under the same pressure as a cooler and there is a slinger in there. At the same time, the higher pressure in the cooler would force more oil out. That is what is intuitive about it.

Over filling could cause main seal failures, but it is really rare with modern crank case ventilation. Usually, the warning about over filling is because the oil can be whipped up into a foam, causing the oil thickness to be degraded, leading to really poor lubrication and blow by, which can foul converters. Both of which tend to be pretty catastrophic.

These coolers do leak really bad, and they really start to piss in the cold. Get a flashlight and look around and below the cooler. The valley will hold a quart+ of leaked oil you cant miss it. And when it fills up and you start driving it runs out the back.
 

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My Ram 2013 Ram3500HD with a big dollar CTD had the same over fill issue. 11 qts filled it but dealer put 12 qt's :whatsgoingon: I never went back even though 3 was free. My JLR had the same Bull shit.
Ummm.....the 5.9 and 6.7 both take 12qts.

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sourdough

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haha, fill line is 11Q its and that info is on many RAM and CTD web sites. 11 Alway was right on the money in my '13 6.7 CTD and I changed my oil at 5,000 miles and it had 68,000 when I sold it. When new I had some free oil change credits. had them do it twice. both time it was filled well over the top mark. Never went back.
 

TGG

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2019 JLU Rubicon 3.6/Auto here. I've had this issue since day one.

Tonight I just came in from doing it's 7th oil change and made a point of researching it... and now here I am.

I noticed this issue after the first oil change, it looked like a faint sheen of clear oil under the two rubber plugs and surrounding areas. I remember the feeling of dread and was very concerned back then as this was a brand new vehicle and I know it's a huge job to repair. I decided to watch and see.

Well, the problem is still there... it hasn't gone away but it hasn't gotten worse. I'll continue to ignore it until it starts leaving drops in the parking spot which I hope will never happen.

The engine runs great otherwise and for what it's worth the dipstick remains near full between changes and that in itself is amazing. I've owned cars in the past that would go through a quart of oil or more between oil changes and didn't have any gasket/seal leaks.

Anyway, thought I'd add it to this thread. It's too bad this issue seems to have been common for some of the early JL 3.6's

Cheers~
 

blnewt

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2019 JLU Rubicon 3.6/Auto here. I've had this issue since day one.

Tonight I just came in from doing it's 7th oil change and made a point of researching it... and now here I am.

I noticed this issue after the first oil change, it looked like a faint sheen of clear oil under the two rubber plugs and surrounding areas. I remember the feeling of dread and was very concerned back then as this was a brand new vehicle and I know it's a huge job to repair. I decided to watch and see.

Well, the problem is still there... it hasn't gone away but it hasn't gotten worse. I'll continue to ignore it until it starts leaving drops in the parking spot which I hope will never happen.

The engine runs great otherwise and for what it's worth the dipstick remains near full between changes and that in itself is amazing. I've owned cars in the past that would go through a quart of oil or more between oil changes and didn't have any gasket/seal leaks.

Anyway, thought I'd add it to this thread. It's too bad this issue seems to have been common for some of the early JL 3.6's

Cheers~
Yep, about exactly as mine, just dribbles enough to moisten the rubber plugs and that's it. My dipstick level is always the same 6k miles later when I do my oil changes. This has been going on for 28k miles now, I'm guessing it's probably about a tablespoon of oil in that oil change duration. I will not let the dealer touch my motor for such a minor issue, time will tell :)
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