Jay420

92 Cherokee 2wd Sport, 120k miles, runs like a champ but burns oil like mad, about a quart every couple days now. And a set of plugs only last me 2 weeks. Put a fresh set in not too long ago and they are toast already, but when I hit the gas she still has all her power.
No visible oil leaks, very small rad leak, and slight oil smell on startup. I nly have dummy lights so not sure of the running temp, but the condition doesnt change with temps.
Also theres a small knock, engine related on the drivers side, but only on acceleration, and more so uphill.

I imagine they are all related in some sort of way. Pugs turn white and have ash deposits on them when I change them.

Stuck valve maybe?? busted head gasket???rear main oil seal???I dont know where to start.
Hope someone can help. Its an awesome Jeep and I plan on keeping it awhile.

offroadordnance

Read my post #23 attached thread

https://www.cherokeeforum.com/f2/oil...142734/index3/

What weight oil are you running?

Edit: it could be blowby or intake valve seals. Does it blow smoke badly out the exhaust upon start up?

Jay420

It doesnt smoke too bad on start up, but I can smell a gassy/oily smell nearly right away. Also seems to kill the #4 plug first too. New wires didnt help. Im running 10w-30 oil and a Fram filter.

storm101

Any chance you have an issue with your air filter being caked in oil as well?

If so check the ports/lines on the top of the valve cover for blockage, as it can cause oil to be spewed from one of the lines on the cover that goes into the air box, and I would imagine eventually sucked in and burnt.

Also a compression check as this point wouldn't hurt your cause either.

offroadordnance

Thicker oil would help until you can fix the problem. Attached explains symptoms of valve seals.

http://www.ehow.com/list_7448959_bad...-symptoms.html

You can pull the hose going from the valve cover to the intake manifold and look inside. If it's dripping, it's an indicator of blowby. If it's dry, it's probably valve seals.

Jay420

Oil filter looks brand new. I tried to do a compression check but my tool wouldnt thread into the chambers. Right threads, right size but no go. I think the tapered end stops it from catching threads.

I wouldnt think compression would be affected. I can lay rubber anytime, even with 235 tires.

Ill try thicker oil to see if it helps, but Id really like to solve the issue instead of sticking a bandaid on it.

tjwalker

A compression test really is the gold standard for burning oil. The compression spec for the 4.0 is 120-150 psi, with no more than a 30 psi variation between cylinders. It is absolutely the first test I would perform is this XJ was in my garage. Many big box parts stores will rent you this tool inexpensively.

Run the test dry first on all cylinders. If any cylinders are low, add a teaspoon of oil and try it again on that cylinder. If compression comes up with the addition of oil, that indicates that you have bad piston rings.

Good data = good decisions.

Jay420

Another major problem is that I live in a very isolated area, with no big parts stores within 1000kms.

Guess Ill have to hunt down another tester and hope this one will fit.

offroadordnance

You could pull off the valve cover and look if the seals are toast or crumbled in pieces, thats alot of oil and it's going to be baked on the valves if you let it go too long. Otherwise, do you have access to a vacuum gauge ?

Jay420

Checked the vacuum from the valve cover to the intake manifold and it does have fresh oil on it. Looking in through the oil cap hole and it looks clean inside.

Ive had a couple friends say its a stuck valve somewhere.

Time to make a few calls on a compression tester and change the plugs again. This is getting expensive.

racebum

you must do that compression test.

a quick one you can use to try and identify a down cylinder is a vacuum test on the intake manifold. when the engine is running vacuum should be stable, if the needle is fluttering it's showing you the down cylinder.

by the way, what are the plugs telling you? are all of them soaked in oil or just a few? my guess is you have 1-2 really bad ones which are the cylinders that are suspect. if all of them are oily the engine was abused at some point, ran with no oil or....well yes, ran with no oil is one of the only things i can think of that would make an engine trash all the plugs. this is especially true at 120k if the cluster wasn't swapped

Jay420

Cluster may have been swapped at some point, Im not sure. Just changed the plugs, back to running brand new again. All plugs are white with ashy deposits on them, no oily buildup.

After changing the plugs I ran her and noticed the aux fan wasnt coming on. And I cant remember it turning on for the last while, if at all. So after a little research here I found the how to run a switch directly to the pcm fan control wire and voila, I have a fan again.

Is it possible I was overheating the plugs to the point they went bad, but not bad enough to stop running???

Still havent found another compression tester and I tried mine again with no luck. Sucker just doesnt wanna screw in there.

racebum

probably not. ash deposits are oil burning. the only question is if it's the valve guides or rings. a leakdown test would be ideal, compression test would tell you a lot. are all the plugs ash fouled or just a few?

Jay420

#3 and 4 go first, and look the worst. Hoping to find a tester tomorrow, in between building the wife her new deck.