First post so Greetings!

I bought a 1993 Cherokee Sport 4.0 HO from a pick n pull for the first couple days driving it no problems and now she's smoking out the exhaust pretty bad. I did a little bit of maintenance on it to start:
E3 plugs, new air filter, new fuel pressure regulator, cleaned out my oil soaked air box (which i thought was causing the smoke), cleaned my PCV and crank case ventilator, oil change, z-max, new oil filter.

I also ran a compression test in which all cylinders where between 120-130 lbs on 4 rotations.

My friends say it is the head gasket yet with the compression test I am uncertain of their decision and think it might just be running rich for some reason of something else. It does spit some water when I have someone rev it to like 3500 and I think it smells like water saturation but it doesn't stop smoking even after an hour of on and off (less than 5 minutes of down time).

Thank you for any advise if worse comes to worse I'll probably buy my friends 4.2 stroked and build the troublemaker into a 4.7 but if I could push that off it'd be nice.

What color is the smoke?

White. Did have a slight blue tinge but after tune up just white.

You should check to see if your spark plugs are wet. It sound like a fuel injector. Maybe your leaking oil where it shoulder be if its blue

Sadly, I would lean towards your friends statement of Head Gasket, but would verify before changing it out.


Have you checked your oil? As in, is it contaminated with coolant? If your white smoke is coming from a head gasket leaking coolant into the cylinders, some of that will end up in your oil pan. Which a quick oil change would show you that.


Check coolant? Is your coolant clean? No oil? Also, is your coolant level dropping?


White smoke out the tail pipe on a Cherokee, Head Gasket would be my first suspect, or cracked head. I would drop the oil and see how she looks. Hope this helps.

Damn he did say there was water
you could prabably seal it autozone has that but its only tempory. Its a liquid type seal. I seen a guy use it after his water pump went depending how bad it is
i wouldent suggest driving untill u check. Dont start it or u could loose a a rod i had white smoke in a pick up i had didnt care being 19 then i threw a rod

The oil looked good when I drained it Sunday and my coolant level is good too filed up my overflow cause it was low then spat it back out. as for the spark plugs when I pulled them to put in the E3s they where definitely dry. and for the reference to my water pump it runs fine my temp stays at 210 and below.

120-130 compression all cylinders sounds like the head gasket is ok to me. Some condensation in the exhaust is just a natural part of the combustion process. White/blue/white smoke is oil burning. Oil is entering the cylinders via the valve stems of by the rings or both. Black smoke is unburned gasoline/running rich.

The blue smoke was only before i cleaned out the air box and unclogged the crank case ventilator now its just white as far as i can tell

From what djb383 said the valve stem would make the only sense as far as leakage of oil into the cylinders if there where leakage from the rings it would have shown on the compression test i might pull the intake and exhaust manifolds and see if there is any oil in the runners around the valve seat

A "hallmark" of bad valve stem seals is it will puff on restart after being parked hot. Let's say 1/2 hr 1 hr. The oil can run down, then when it's started it will smoke at first.

Are you sure it's actually coming out the pipe? Oil leaking from, say the oil filter adapter O rings will blow back to where the exhaust crosses over behind the pan. There it burns, and in the rear view mirror...well you get my idea. You might look at the pipe where it crosses over.

You can tell quite a bit just by wiping the inside of the tailpipe with your finger. Antifreeze has a distinct smell as does excess fuel, water does not, oil smoke leaves an oily film...

My 4.0L HO had good compression turning it over with a blown head gasket, did a cylinder leak test and didn't need to look at the gauge, as soon as you applied pressure it would bubble in the radiator. I was just happy it was only the gasket and not the head itself. Mine had no smoke, no fluids mixing, I check due to oil weeping onto my block on the right side. Caught early.


Hopefully it's not a head gasket in this case, someone did a write up on the automatic transmission module on these could suck trans fluid back up the vaccum and cause white smoke out the tailpipe also. While try to find it when I get a chance.


The smell of the exhaust would tell a lot.

There r multiple places a head gasket can be bad. Since the OP was stating 120-130 range all cylinders, it sounds to me like the head gasket is good between cylinders.

yes check tail pipe as stated.. then check and see (when Cool) if you get bubbles out of the radiator with it running