Hi,
2001 XJ, 275K miles. It drives/runs pretty well. However, for the last several years, it has had a slow antifreeze leak where the coolant disappears. There is no coolant in the oil, and the oil level is steady. Engine performance is fine. When I noticed this (about 50k miles ago), the mechanics told me to just keep an eye on it and that the 4.0L engine is practically indestructible.

I am noticing that I am having to put a lot more coolant in these days. I probably add a gallon of 50/50 every 4-6 weeks.

The local shop pressure tested this to see if I had a radiator leak and it tested fine, so their theory was that the coolant is probably bleeding past the head gasket at some point and atomizing in the exhaust.

That would explain why I have gone through a muffler and a cat in the last few years (had to replace both of them this year). I am guessing that the coolant is superheating the cat and probably not great for the muffler.

Anyways, here are my questions:

1. If it is the coolant getting blown/boiled out the exhaust, can I just replace the head gasket? (guessing everyone here will say to just get the clearwater head, but thought I would ask).

This has the infamous 0331 head so far as I know, but I have never seen coolant in the oil.

2..My next question is this: Does it make sense to put in a new head on a block that is at 275k miles?

This XJ is going to be my son's when he turns 16 in two years. The goal is to keep her going until he can total it in his first accident.

3. Would I be better off buying a low miles XJ (with ~150K miles) for 3500ish and getting rid of this XJ?

Thanks for any thoughts

 

This is a decision that would be better made AFTER the head is off and everything is inspected. It all boils down to one difference... Do you mind getting your hands dirty or not? If not then no sense going any further with this question...

 

This is my 3rd XJ. No problem getting my hands dirty. And my son is finally old enough to help. I have owned XJs for 15 years and done quite a lot, but I've never pulled a head. I have no doubt I can do that. I just don't know how to inspect it....

 

If you are up to getting your hands dirty... then all the rest is why we are here! There are at least ten users here who would help walk you through this inspection process!

The problem would be how much damage you might run into after you get the head off. In my experience so far as a master tech learning on these is they are pretty hardy and resistant to extended damage and a head job is pretty easy.

Just don't let it sit too long before you pull it down and get that water out of those cylinders. The longer it sits the more damage will be done to the cylinders and parts. I would get on it right away if you decide to get it done yourself.

Personally I would have been on it already and been in there to take a look. You can always throw another gasket on it and sell it. Gaskets are cheap... But would it be morally correct?

That I will leave up to you... lol

 

It would be very valuable knowledge acquired for both yourself and your son...

 

Here's what happened to mine a few months ago before I rebuilt the engine:

Same as yours... Started to slowly use coolant with no signs in the oil or radiator.

It got worse and it seemed like the hotter the temp was the more it used.

Finally during a run pulling a trailer it actually got hot and I had to let it cool down and refill it.

Head being suspect I took the time to take a good look.

When I did... I found that the "exhaust leak" I had been hearing was actually compression pumping out the side of the engine where the head meets the block on #1 cylinder...

No question and pretty rudimentary after that... lol

 

Get an oil analysis done. That will tell you if you have coolant in your oil and consequent bearing damage.

Also do a test for exhaust gasses in the coolant.

If you are good on the oil test, open it up and give it the hairy eyeball. If it looks good, slap a gasket on there and get on with life. If not, plan B.

275K on the block? Just getting warmed up.

 

Lol... Yep.

 

I apologize for my ignorance here...but what are you saying happened? Where was the coolant going?

 

Ok. I ordered the Blackstone Lab kit. How would I be driving the cherokee daily if there were serious bearing damage? Wouldn't the engine have given out by now if there was that much damage? Sorry for the idiot questions...

 

Nope... Early warning preventative maintenance. Well worth the results they can give you. But... It doesn't always leak to your oil. It can be going out your exhaust and not be putting one bit into your oil at all.

Yet it is very good advice because there just might be enough sneaking past your rings to get a reading from this... Mark is right... It can indeed tell you quite a bit.

 

1. These engines are amazingly tough.
2. It might not be really bad..... yet.



I haven't seen any yet.

 

It was passing between cylinders and out the exhaust. But not in enough flow to tell. Finally other factors came into play and gave indication the gasket was bad. Just so you know... If it hadn't been for the valve seats being so bad and valves so pitted I could have used that head over again. Rather than pay the cost for all new valves it was cheaper to get a good junkyard head with good valves and relap those. As Mark says... These really will take a hammering and be ready to go with a new head...

 

Hi all,
I am not sure if I should start a new thread, but I got the Blackstone results back on my oil. I attached the full report. Here are the comments:
The Jeep drives ok now. I get the check gauge light since the oil pressure dips to 0 if I am at a stoplight. But I need to decide what to do with this XJ.

It would seem like the head replacement is not going to fix my problems and I am looking at a full engine rebuild. While I might be tempted to try that (and I think it would be great for my son and I to do together), here are some realities: 1) There are some other things that need fixing on this XJ (a/c, new rear end, and whatever else might come down the road after 275k miles, 2) this jeep is our daily driver to go surfing. I have another car but it will not haul surfboards; if we start to rebuild the XJ, I am going to need another vehicle anyways to go surfing, and 3) I regularly see XJs with 100k miles for sale on craigslist.

My thoughts now are to just buy a new XJ, sell this current one for parts. But I am asking others here what their thoughts are. If I were to buy a new XJ, I would think of a 99 or earlier so I don't deal with the 0331 head issue anymore.

Any thoughts or advice is appreciated and I am very grateful to BlueRidgeMark for nudging me towards the oil analysis. Thanks to all.

 

Rebuild the engine. Cost around $1000 with all new parts and machine work. Plus you get to teach your kid something awesome!

That is, unless the rest of the Jeep is rotting away... then I would go a different route.