Rear of Engine oil leak


Parts Collector
NAXJA Member
Is there a cam plug or some other plug on the backside of the 4.0 that would leak oil? I get a few drips out the inspection cover and the rear main seal area is dry.


nobody of any consequence
take a closer look at the valve cover area in the rear. pretty sure i've seen some kind of plug back there but it may be a freeze plug.

Rick Anderson

New member
My 2.5L (the 4.0L with 2 cyl lobbed off) had the entire rear of the engine wet with oil and got all inside the bellhousing, when the changing the clutch the rear main seal area was dry.

In my case, it was the Valve cover gasket, it just barely leaked around the sides/front, but leaked like a civ at the rear of the valve cover. The Fel-Pro I used first didn't fit well, while the Reinz gasket fit much better and hasn't leaked yet.


New member
There is a cam plug..

Try this:

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, people on Jeep forums who can’t see your Jeep from where they’re at, 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. "$hit 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 02-26-2013