Leaking main seal?

[Motorhead X]

I just finished a valve cover gasket job yesterday, it went fine. Then started her up to make sure it was ok and oil started pouring like Niagara Falls out of the rear main. Dang. It's not the valve cover either. The RMS has been leaking a little bit for a while. I was crossing my fingers that it was the valve cover dripping down.

 

My neighbor just asked me if I changed the PCV on the valve cover when I did the gasket (I think it is called a CCV on the Jeep). In fact I did change the whole assembly connection to the air filter. He thought that maybe I created a positive pressure situation inside the crankcase which is pushing oil out the main seal. Could the return CCV tube to the intake be clogged and causing the major oil flood on my driveway?

[cruiser54]

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.

[Motorhead X]

Hey Cruiser, thanks for that info. I am working specifically off of your previous post(s) that had the same recommendations. That is why I did the valve cover gasket first. Now, the top of the motor is dry. No oil is leaking above the oil pan/RMS area. After the first gusher, I dried as much of the motor off as I could, so I think we are covered on your list of items. 

 

Back to the ccv... I replaced the front hose that brings fresh air into the valve cover. I also just took off the hose and connections that go from the back of the valve cover to the intake. I confirmed the thin connector hose is totally clogged.

 

So now I am looking for info on these two elbow connections. Here are the old elbows in the pic. The janky broken one with the large diameter hole was on the front previously and I replaced it with a Mopar elbow with a small hole. Should the back elbow really be the large diameter?

[cruiser54]

Parts stores should have those fittings for the valve cover. Good find by the way....

[Eagle]

Keep in mind that the larger air hose to the valve cover (the one in the front) is an intake hose. For the CCV system to function as designed, the skinny little line toward the rear of the valve cover also has to be open, because that's the one that uses engine vacuum to create a negative pressure in the crankcase to suck out fumes. It's not a great design, because hot, oily fumes tend to clog up the little line. Once that happens, you no longer have a crankcase "ventilation system" -- you now have a crankcase that gets pressurized by piston blowby, and the pressure goes out anywhere it can. If the front intake tube is also clogged, it'll force the fumes (and oil) out the rear main seal. I once had one blow the oil fill cap right off on the highway.

[Motorhead X]

Alright then! Thanks fellas...It looks like we're on to something here. The front elbow should be the large diameter hole (black color) and the back elbow is the small hole (grey color).