Kyle Post

I was driving on the high way and Rpms were high then I was getting off the high way and smoke was pouring behind me out of the exhaust then I stopped and looked and I was leaking oil bad so the smoke was from the oil hitting exhaust but I'm confused as to what is bad its hard to see with oil every where I have a couple pictures that may help, I'm thinking its possibly the rear main seal? What do you guys think

tech

The 1st thing you need to clean it up and then check the around the back side of the valve cover for a oil leak if it is clean and no oil leaking from the cover then it will probable be the rear main seal .

Kyle Post

it looked like some or all of the oil was transmission fluid (redish looking oil) so I'm confused on that if tranny oil can come out of the rear main seal also

tech

If it is trans oil then it could be the front pump seal to the trans ,you have to find out what oil it is .

fb97xj1

If its red, its transmission fluid. Doublecheck the transmission lines where they pass the oil pan for leaks, as well as the transmission pan gasket, just because. Any drips down there will get blown around. You can also remove the inspection plate and look inside the bellhousing. Grab a flashlight. If you can see evidence of trans fluid coming from behind the torque convertor, the pump seal is suspect.

tech

You need to see if the oil leaking matches the engine oil or the trans oil .

cruiser54

There are many places it could be leaking. The absolute LEAST LIKELY is the rear main seal.

I wrote this over a decade ago as a guide.

I’d be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.

Everybody, who doesn’t own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking. Many mechanics, friends, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?

A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don’t jump on the RMS/oil pan gasket bandwagon right off the bat.

Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons:

First off, the engine sits nose-up and any oil will run back to the RMS area.

Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber’s adage apply here: “Crap flows downhill”.

Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first.

Revised 1-31-2016

GreaseMonkey17

EZEARL

A new one cured the major cause of my leak.

cruiser54

Very typical. Great job.

Ozalid

Interesting, I have been chasing a leak that looks like yours, but not as bad... Up to this point after looking at all the things recommended in the leak threads, I was defaulting to a rear main seal, even though it was changed out 6000 miles ago....
But you pointing out the color of the oil has me second guessing again... I recently had the oil and filter changed..so the oil is very clean. I just assumed the color was a result of it picking up dirt on the way out....
I'll get back to you after I look a little closer at the oil color.