Hey everyone, my wife broke down on the highway and she heard a loud sound along with white smoke from the engine bay, the Jeep runs but smokes a lot and she said oil is leaking from the exhaust. She said the oil is low on the dipstick and I'm wondering what your thoughts were. I'm thinking a bad head but hoping it's nothing worse, any tips?

 

Year and confirm engine size please.

If it's an 00-01, they do have a head defect that's common.

Oil shouldn't leak from the exhaust though... oil gets burned in the engine and leads to bluish smoke. White smoke is usually coolant burning. An oil leak that covers the part of the exhaust pipe right behind the engine is usually due to gasket leaks.

What's the oil pressure readings? It's pretty common for the 4.0 to burn a little oil. My Dad's 94 burned a quart between changes from the day he bought it (brand new) to the day he retired it with 400k original miles on it.. That engine still ran beautifully, easily could have gone to 500k, he retired it solely due to rust.

EDIT -- If the smoke's from the engine bay, it could be any number of things leaking coolant - It could be a rusted out exhaust system pre-cat... that exhaust will be thicker and whiter than the tailpipe exhaust. Can you see where the smoke seems to be originating??
Maybe put a coolant pressure tester on it and look for leaks (get the tool as a loaner at your local parts store).

 

Mechanic is looking at it but according to my wife it was leaking in the exhaust. IT WASN'T. Literally 0 oil in the oil pan when the mechanic knocked on it. It's a 2000 Jeep Cherokee Sport

 

The engine can't run (for more than a few seconds) with zero oil - it will seize the engine.

So either it seized or zero oil is a gross exaggeration. I'd bet it's 2 issues, an oil leak that has been neglected AND something busted with the exhaust or cooling system. I tend to think exhaust pipe broke, but you'll know soon enough.

You need to have a talk with your wife about basic vehicle maintenance. She needs to be aware if she's seeing a spot in the parking spot, and aught to check the oil every once in a while... at a minimum. Teach her to check the coolant, brake fluid, tranny fluid etc. And ensure she does it once a month or more and to inform you if anything is not in spec.

Edit -- The wife thing isn't specific to the XJ, it's true for any and all vehicles. However, it's particularly important for older vehicles and 20+ years is definitely old. The earlier you can catch and correct a problem, the cheaper and easier it will be to fix and you won't be getting as many panicked calls from loved ones being broken down on the side of the road.. lolol

 

My guess is that your wife was seeing condensation out the tail pipe (it usually comes out black and looks like oil). As for the smoke in the engine bay it could be from many many things. I personally had an oil leak from the pan onto front oxygen sensor that smoked like crazy and eventually messed up the O2 sensor. And FYI the 4.0 can run on virtually no oil - my wife's ZJ 4.0 used to burn oil so badly by the time I changed it the dipstick read nothing and was draining out maybe a 3/4 quart? We retired that Jeep at 290K.

 

Not so, Sir Patrick. My son proved that a few years ago on my 97. He was doing an oil change and had it up on ramps. Got the oil drained, filter out, put the plug back in, then started it up and took it down off the ramps so he could reach in to replace the filter. Came in the house to get the new filter and left it running. I about killed him, but the Jeep didn't seem to mind. I kept a close watch on the oil pressure, but it was fine. Well, until that Suburban pulled out in front of me, but that's another story.

Years ago there was an oil additive that claimed to be so slick that you could put it in an engine, run it a bit to circulate it, then drain the oil and drive the car. To prove it, they put it in a Vette, ran around the track a few times, then took the oil pan OFF, and ran around the track a few more times. Very impressive!

Until somebody came along and did the same thing with just ordinary engine oil.


So, yes, running with no oil will grenade your engine, but it takes a few minutes.

https://www.youtube.com/results?sear...ne+without+oil

 

Texaco did a TV ad like that with Havoline about 50 years ago