Hello,
I am sure this topic has been discussed a million times but my particular set of circumstances are leaving me very confused.
First the Stats:
1993 Jeep XJ 4l Ax15 with 240,000 KM on the clock. Upgraded Ev4 injectors but everything else is stock. Recently had cat hogged out because it was falling apart inside.
Sometimes my rig is blowing oil smelling smoke out of the exhaust but it is very inconsistent. Sometimes when I start it it will smoke for a bit and the smoke will increase for a puff if I rev the engine. Sometimes when I start it there is no smoke. Smoke also seems to appear after running for a while then restarting.
Engine looses oil slowly. Does have a few small oil leaks. Also looses coolant slowly but I am pretty sure it is coming from the upper radiator hose which I can't get to seat properly on the damn thermostat housing because the valve cover is in the way.
Engine has no blowbye. The CCV or PCV hoses are clean. No oil showing up on air filter. Good oil pressure. Does not overheat. Just checked all the plugs and they are pretty mint looking. If anything they look a little lean but no signs of oil. Haven't checked the compression because my tester is currently 1000km away. Recently overfilled the oil a little bit, did this do damage? Engine used to have a bit of lifter tick when cold but this seems to have gone away a few months ago. Seems to have lots of power.
I am pretty stumped. Is it the valves? Rings? My buddy suggested that oil might somehow be getting into the exhaust manifold and burning, but I am not sure how this would be happening.
Any thoughts? I am pretty bummed because I love my jeep and have been putting a bunch of time and money into fixing it up and thought the engine had many years of faithful service left.
Cheers

 

Im pretty sure if it was rings you would see it on the plugs with build up.

 

I'm betting on bad valve stem seals.

They can be replaced without removing the head.

Only way to be sure before proceeding id do a leakdown test on the motor.

BTW, welcome to Cherokee Forum.

 

Thanks guys, this forum rocks. Is it worth it doing valve work with 240,000km? I just started a new job so might not have time to get to it for a few weeks. How much harm does driving it like this cause? Cheers

 

It's worth it, that's only 150,000 miles, plenty of go go left. Just keep the oil topped up and get to it when you can.

 

No harm driving it.

You're not gonna be "doing valve work" but just replacing their oil seals. No worries.

 

Update*** damn thing didn't smoke at all today. Didn't drive a huge amount but why the inconsistency?. I guess leakdown test is in order.

 

Any changes? Oil change? Anything?

 

No Changes. I am planing on changing in 10w40 soon. I will update if the mystery smoke comes back haha

 

Try this.

First, assess the sludge buildup on the rockers etc by shining a light into the oil filler hole.

Let us know what you see.

I would suggest Rotella t3. 5 quarts of it with a quart of Marvel Mystery Oil.

Napa Silver or Gold filter.

 

Rockers look just as clean as they were when I changed the valve cover gasket 2000km ago. Nice amber colour.

 

Just stick with a good oil and filter and see what happens then.

 

Update!
Havn't been able to change oil yet. Working 12 hr days. But! Seems to be burning oil once the engine is hot. Exhaust looks pretty normal idling hot but when I blip the exhaust a little oily smoke comes out. Nothing extreme. Can anyone shed light on what this means?
Cheers!

 

Typical valve stem seal symptoms..............

 

Oh Yeah? Good news if that helps the diagnosis. They will be dealt with ASAP. Thanks for all the help!