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JK 3.8 Oil leak problem

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Old 02-26-2017, 03:00 PM
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Default JK 3.8 Oil leak problem

I have been having oil burning or leaking problems on my jeep for a few months now. Not really sure what is causing it but I have recently discovered a leakage on top of the engine. Not exactly sure what the part. It appears to be loose and is apparent that oil is coming from it, but I'm having trouble finding something to tighten it with. I am afraid to mess with it because I'm not exactly sure what it is if anyone could help me out here that would be great. I guess all I'm trying to ask is if anyone has encountered this before and how did you fix it. I can't get a normal wrench on it. BTW, I did change my PCV valve about 2 months ago and that didn't seem to do much with the oil disappearing, so this is the only thing I can go off now
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(the thingy with the red on top)

Last edited by JarettNuskievicz; 02-26-2017 at 03:14 PM.
Old 02-27-2017, 05:12 AM
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The part you are referring to is your coolant temperature sensor. If loose or damaged, this part would leak coolant, not oil.
Old 02-27-2017, 05:42 AM
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Originally Posted by Potato Potato
The part you are referring to is your coolant temperature sensor. If loose or damaged, this part would leak coolant, not oil.
Okay thank you!
Old 02-27-2017, 05:47 AM
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No problem.

My JK consumes/leaks about a quart between 5k oil changes. I have small drips in my driveway from what appears to be a rear main seal. Are you finding drips where you park or just noticing oil consumption?
Old 02-27-2017, 06:54 AM
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Like Potato said, the 3.8 burns oil. Its a well known problem. Its not until you start seeing drips that you have a real problem.
Old 02-27-2017, 09:03 AM
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Originally Posted by Potato Potato
No problem.

My JK consumes/leaks about a quart between 5k oil changes. I have small drips in my driveway from what appears to be a rear main seal. Are you finding drips where you park or just noticing oil consumption?
I check all over the place to see if I can see where oil may be coming from but can never find anything. A few months ago I began to notice wetness on top of the engine, figured it was a small oil leak somewhere but now I guess it is the coolant coming from the sensor. Other than that I notice nothing and always double check the filter and plug to make sure it's on right.

I only go right around 3k miles per oil change. Last time I changed it about 4-5 quarts was gone On the current change I have roughly 1125 miles on it. I checked it yesterday and had to add about a quart and a half to bring it back up to where it needed to be. I have always ran 5w-30 in it just because it was a little thicker rather than the 20 it calls for but doesn't seem to be doing much help.

Not really sure what to do other than just keep extra oil with me
Old 02-27-2017, 09:25 AM
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Originally Posted by JarettNuskievicz
I check all over the place to see if I can see where oil may be coming from but can never find anything. A few months ago I began to notice wetness on top of the engine, figured it was a small oil leak somewhere but now I guess it is the coolant coming from the sensor. Other than that I notice nothing and always double check the filter and plug to make sure it's on right.

I only go right around 3k miles per oil change. Last time I changed it about 4-5 quarts was gone On the current change I have roughly 1125 miles on it. I checked it yesterday and had to add about a quart and a half to bring it back up to where it needed to be. I have always ran 5w-30 in it just because it was a little thicker rather than the 20 it calls for but doesn't seem to be doing much help.

Not really sure what to do other than just keep extra oil with me
Thats a lot of oil after only 1k miles... IIRC the capacity is only 5ish quarts? Mine was seeping pretty bad from the oil pan gasket, where the pan meets an adapter at the motor. A gasket change fixed that.
Old 02-27-2017, 09:44 AM
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Originally Posted by Ajkaz
Thats a lot of oil after only 1k miles... IIRC the capacity is only 5ish quarts? Mine was seeping pretty bad from the oil pan gasket, where the pan meets an adapter at the motor. A gasket change fixed that.
I believe it's around 5.5-.6 or so. Were you noticing any leaking from around there?
Old 02-27-2017, 09:57 AM
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Originally Posted by Ajkaz
Thats a lot of oil after only 1k miles... IIRC the capacity is only 5ish quarts? Mine was seeping pretty bad from the oil pan gasket, where the pan meets an adapter at the motor. A gasket change fixed that.
Sorry, I misread what you said. I'll definitely have to check that out to see if it's leaking down there. Thanks!
Old 02-27-2017, 03:38 PM
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My 2011 3.8 has lost about 1qt/1k miles of 10w30 on average since new. I carry a 5qt container of 10w30 oil with me and just add about 1 qt every 1000 miles. I now have over 100k miles on my hybrid "diesel/gas" JK, lol. (Yes I have added over 100qts of mobil 1 over the last 6 years, I like that Mobile 1 burns clean lol!)

A few months ago after an aggressive wheeling trip I checked my oil at the 1000 miles mark and it was down about 2 quarts. This is unusual so I started poking around I found a lot of oil under the engine. It was weeping down from the oil pan seems, Upper and lower oil pans. Also above the junction of the tranny and engine block there were drops. Topside looks like the seem where the valve cover met the block also weeping. I started researching...

I found the 3.8 engines are known for lower intake manifold gasket leaks. These drain down the backside of the block and drop off the bottom junction of the bellhousing and block, presenting as a rear main seal leak but rear mains are uncommon leaks on the 3.8 engines not like the older TJ's where this was the main oil leak you see.

So I changed the valve cover gaskets, lower intake manifold gasket, upper and lower oil pan gaskets (lower is actually just RTV sealant), and for good measure the PCV valve. After about 2 months now I have been consistently losing (burning? Who knows?) 1qt/1k miles again.

There is not one drop of oil or any sign of seepage anywhere on my engine now and all is good with my hybrid "gas/diesel" engine once more...

Last edited by Biginboca; 02-27-2017 at 03:53 PM.


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