so i picked up a 2001 xj about 6 months ago, which now has around 186xxx on it. bought it and nothing visible wrong really and mechanic only found a few little things that have since been fixed or will be soon. well i started loosing coolant at a good rate. i go through about a jug or two a month. there are no visible leaks that i have been able to see but im putting cardboard under it soon to double check. oil pressure runs around 40 at first start but starts to drops around 15-20 when driving and to zero after about 30 secs at idle. no rough idle, no white smoke and changed oil yesterday which was black. no milky oil kind of stumps me on what the problem is. any ideas? i know the heads tend to crack on this year with this many miles. any help is appreciated

 

Start with a compression test, then pressure test the cooling system.

 

^^Good suggestions above.


Cue "Night on Bald Mountain". Sorry, just kidding. I suffered a cracked head last month and I'm trying to lighten the subject.

But seriously, it sure sounds like the proverbial cracked head issue. Check the oil level to see if it's higher than it should be. That's a sure sign you have coolant leaking from the top of the head.

Also remove the oil filler cap and look at the bottom of it. Check for any milky residue. Any sign of it is another indicator of a cracked head. Another indicators is steam coming out when you remove the cap.

Finally, get the engine up to operating temperature and, while the engine is running, climb up from the side of the vehicle to avoid the serpentine belt and very carefully shine a bright light through the oil filler hole. Conveniently, it's located directly above the area on the head which tends to crack. If it is cracked, you will be able to see coolant seeping out of the crack.

I hope you have another issue, but definitely rule out a cracked head as part of your troubleshooting. If you have a cracked head, we can help you decide how to proceed.

 

01 XJ, losing coolant, and low oil pressure frequently means your head is cracked and there is enough coolant in the oil to destroy the crank and cam bearings. As suggested, pull the oil filter cap and straight down between the rocker arms. If there are any signs of coolant, a "tan line", etc. then you have a problem. You might also take an oil sample and send it in to a lab for analysis. Oil labs will test of the presence of coolant, potassium, etc. High potassium means coolant. Consider the case of external leakage burning off/hard to see. Also consider that the engine had a bad head, which was replaced, and now the replacement has a problem. If oil pressure is truly that low, drive it until it blows, or replace it. If the head is good then the head gasket may be the problem, or the block might be cracked. Just some thoughts.

 

Wondering why my jeep smokes out of the engine where i pour the new oil. It seems to be full. Also smell a burning smell im lost

 

Go to this thread and ask that same question.
https://www.cherokeeforum.com/f2/ask...772/index3265/

 

Thanks guys. I'm going to check the oil cap in an hour or two, I'll let ya know. If it's a cracked head I have the money saved from taxes for a new one and a few buddies who will help me put it in. I just need this baby to run for another 5 years or so. Already replaced a break line and fuel pump. Hope this is the last big thing for a while Haha. This head might delay the new lights I wanted to get 😢

 

I had the same thing happening to my 00. No visible leak and oil level was where it should be, my oil would fluctuate from 60 down to about 20 at idle. It turned out I had a cracked head and cracked block. I had a new engine and head out in. Now she runs like a champ and hasn't complained once!

 

When my head cracked it was loseing coolant in the chamber And was barely noticeable out the exhaust. Doesn't always crack and leak coolant into oil.

Compression test and check the sparkplugs for color as there would be evidence there as well.

 

Do you recall how many miles were on your Jeep when the fuel pump went out? I'm wondering when I can expect my fuel pump to quit.

 

i think it was around 185xxx. dont think it happened more than 1k miles ago max.

new question, will a head from a 91 Cherokee would bolt right on?

 

Compression test is not the best test for a cracked 0331 head. I've seen a few pass this test but have a cracked head. Cylinder leakdown test is much better. But many have been able to actually see the cracked head by looking inside the oil filler cap with a good light. Cylinder 3-4 is right there. Do this FIRST as it's quick and easy. If you see the crack, you don't need to go any further. But if you don't see the crack, that doesn't rule out a cracked head.

Don't underestimate potential damage if the head has been cracked long enough (and it doesn't need to be that long). If it isn't caught quickly, then the coolant mixing with the oil will toast the engine bearings and you'll need either a different engine or a rebuild. Simply putting a new head will NOT be a complete fix. I've seen plenty of guys go down that road only to be disappointed.

Good luck and keep us updated!