Oil everywhere!

Specs: 89 XJ, 4.0L, AW4, D30, 8.25 with discs, 176k miles on the motor

Possibly relevant mods: Rustys cold air intake, Rustys throttle body spacer, WJ dual diaphragm brake booster, IAC about 2 years old, knock sensor and O2 sensor about half a year old, TPS hasn't been adjusted in the last 6 years or longer so it might be due.

Within the last year or so I noticed the XJ's oil leak went "It's a Jeep Thing" to "OMG where is this all coming from?"

The entire motor and transmission appears to be covered. I mean even the top of the valve cover. I've been going through almost a quart a week if I drive it every day.

In the spring on a long 6 hour drive on a hot day I started getting a lot of oil blow-by in the cold air intake. I removed the hose from the intake tube, the one that is connected to the front vent on the valve cover, and stuck an air filter on it for the oil to drain from, and hopefully keep junk out.

Fast forward to fall and I'm tired of oil leaking out of that onto the fender and the oil coming from what appears to be everywhere on the motor.

Tonight I went to remove the valve cover so I could put a new gasket under it and replace the vent hoses. Well, I guess when I last removed the valve cover to have a look at things back when I bought the Jeep in 2005 I put the bolts in and over time the worked loose. Every bolt (except the one farthest back, naturally) was barely tight. I really didnt need a ratchet. The socket could be used alone to remove the bolts. That explains a lot of my oil leak. Doh!

The next thing I found was that the small vent line from the back of the valve cover to the front of the intake manifold was far from making a seal on the barbed connection so that might explain my rough idle.

Did I mention I have a rough idle?

It comes and goes so I'm not too concerned. I'm hoping this vent line fixing that I'm doing will help it, along with a TPS adjustment, and a new set of cheap Champion plugs.

Anyways, I'm going to be replacing those vent lines on the valve cover and putting in a new gasket (and checking the bolts after a few heat cycles).

Any other suggestions for curing my oil blow by and excessive leak issues?

I also had a oil pan gasket and rear main seal ready to go in but I'm going to wait and see if they're needed after this valve cover issue is fixed.

Thanks for any advice.

Josh

Once you get the valve cover tight and the gaskets and grommets right, make sure the vacuum line for the crankcase vent is utterly clear of gunk and buildup. Carbon and sludge can narrow it at the curves and mess up your ventilation, which is a delicate balance at the best of times. If you somehow still have the original setup with sharp 90 degree elbows, replace it with the updated type which uses wider curved elbows. It actually does help.

ON my old 87 the valve cover worked loose constantly. I don't know why, but the later ones seem less prone to that. Checking those bolts was a part of routine maintenance.

A dab of Loc-Tite Blue on the bolt threads might help...

Many years ago, I had oil everywhere. Dropped it off at a dealer and they replaced the valve cover. After awhile, oil everywhere and back at the dealer again. They replaced the valve cover again. After the third time, I replaced the valve cover gasket and there was oil everywhere again. Eventually, when I rebuilt/modified the engine and auto trans at 385,000 mile I discovered a broken ring. It would've been nice if the dealer had mentioned a broken ring, but I guess replacing valve covers makes more $$$ for dealers.

My mistake was "assuming" the dealer had checked things out. This was an expensive lesson learned for me. Now I do everything myself and I'm a lot happier. If you've got a broken ring, it pressurizes the crankcase and blows oil out everywhere. Check compression. If you need to re-ring your engine, buy the BEST rings available, i.e. unbreakable top ductile iron ring or the newer stainless steel rings. They'll cost you about a $100/set but worth every penny and they'll never break.

Best regards,

CJR