1999 XJ Cracked Head?

I keep telling myself that i'm paranoid, but i think my 1999 XJ head is cracked.

I just replaced the radiator/thermostat housing/thermostat/water pump because i thought my radiator was leaking, and i'm still having "unexplained coolant loss".

I just refilled the bottle tonight was 50/50 mix because it was missing. I saw coolant leaking out of the hose that goes from right next to the rad cap to the bottle (think that's the overflow tube). Anyways, i put a hose clamp around it, and coolant is still going missing.

I just removed my oil cap, and found this on the bottom. Looks almost ... milky? Is it possible that my 99 head cracked? Why would that happen? Would it explain why my jeep doesn't like going over 3k RPMs? Would a compression test tell me if it's cracked?

Maybe it's not the head, and just the head gasket is gone? Anyway to check for these? Any other tests i could do? How long would a head gasket job take?

**EDIT** Jeep has 118k miles on it. I noticed the coolant loss about a month ago, kept topping it off for about a week, and then i changed out the entire cooling system. Do you think i cooked anything else in the engine to the point where it's more than just a head gasket? I'm seeing dollar signs right now.

Any other ways to tell/check for it?



Picture is my oil cap.

I'd put my money on a head gasket, the 2000 and 2001 are the ones that have the weak heads on them, I don't believe any of the 1999 XJ's had that problem. You could do a head gasket in probably a day or so if you keep at it. But it definitely looks like you have water in your oil from something

JRT1393 said:

I'd put my money on a head gasket, the 2000 and 2001 are the ones that have the weak heads on them, I don't believe any of the 1999 XJ's had that problem. You could do a head gasket in probably a day or so if you keep at it. But it definitely looks like you have water in your oil from something

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That's what i thought. I hate to hear that though. That's the last thing i wanted to do. Why couldn't it just have been the radiator? AAAH.

Thanks for confirming my suspicions.


**EDIT** Jeep has 118k miles on it. I noticed the coolant loss about a month ago, kept topping it off for about a week, and then i changed out the entire cooling system. Do you think i cooked anything else in the engine to the point where it's more than just a head gasket? I'm seeing dollar signs right now.

Oil Dipstick looks fine.

But is the level higher than normal. . .
Also, you can have a breach of the HG between a coolant passage and a cylinder(s) and the coolant will exit in the exhaust fumes. You should do a compression check. How does the Jeep run? Is the check engine light on?

Pull the plugs and take a look at them. That might
at least point to a specific cylinder.

Is there visible vapor coming out the tailpipe,
when at operating temperature?

Remove the radiator cap and see if there are
bubbles present while idleing.

It's difficult to tell whether the problem is a
cracked head or faulty headgasket without
pulling the head. If it hasn't overheated, I'd
assume a failed headgasket...

gradon said:

But is the level higher than normal. . .
Also, you can have a breach of the HG between a coolant passage and a cylinder(s) and the coolant will exit in the exhaust fumes. You should do a compression check. How does the Jeep run? Is the check engine light on?

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My HF compression gauge will not screw into my spark plug hole for some reason. I might need to actually buy a good quality one or borrow one from a local Advance Auto if they lend those out.

The jeep runs fine. Quite honestly, the only thing i noticed different is that the coolant is kind of disappearing.

The only other thing i could think of is the cooling system just burped out all the air in it, and i just had to re-fill it and now we're good. I just thought that it burped a lot of air out for just about the entire reservoir to be empty.

Check engine light is not on.

Runnin'OnEmpty said:

Pull the plugs and take a look at them. That might
at least point to a specific cylinder.

Is there visible vapor coming out the tailpipe,
when at operating temperature?

Remove the radiator cap and see if there are
bubbles present while idleing.

It's difficult to tell whether the problem is a
cracked head or faulty headgasket without
pulling the head. If it hasn't overheated, I'd
assume a failed headgasket...

Click to expand...

Just pulled the spark plugs. They all look fine to me. Picture is of them below.

When you say vapor coming out of the tail pipe do you mean like a lot of water dripping from it or like white smoke?

Will remove the rad cap and let it idle once the jeep cools down. I just drove it around a little. Will report back on that.

How do i tell if the head is cracked/warped? I know cracked is easier to tell than warped. I first noticed that my radiator was leaking when the temperature gauge got up rather high. It got to maybe 220-225 degrees and then i stopped, topped off the water, and kept driving. It hasn't gotten that high since. After the new radiator, water pump, etc etc, it won't even get to 210 when i'm driving.

Picture is my spark plugs.

On the right side is the very front of the engine (towards the headlights) and on the left side is the farthest back plug (towards the cabin.)

Plugs look normal to me.
However check to see that the CCV system is working correctly. Check to be sure the hose is fitting tightly to the nipple at the intake manifold and that it(hose) is not broken anywhere along its length.Check for vac at the valve cover connection.
Also short trips in cold weather will allow the condensation to build up in the oil

If your compression is good(done on a warm-up engine), then I'd doubt you'd have a warped head.

I agree plugs look good. The oil also looks OK,
at least on the dipstick.

If there are no bubbles in the radiator, and no
white vapor coming out of the tailpipe when
warm, I'd look further before pulling the head.

The coolant leak could be a heater shut-off
valve, radiator hose, etc. that seeps out and
then evaporates before reaching the ground.

You still could have head problems, but there's
no obvious signs that are showing up...???

Coolant loss can have other causes as suggested. Perform a cylinder leak down test to check the head and gasket. By applying compressed air to each cylinder in turn (with that cylinders intake & exhaust valves closed) you can isolate any faulty cylinder.

Have oil tested by a lab for contaminants (like coolant).

White goo on the oil fill cap can be from simple condensation. Make lots of short trips in cold weather ?

Just got home from work. Been plowing mountains of snow all weekend. Let me answer these before i pass out from sleep deprivation.

Wayne Sihler said:

Plugs look normal to me.
However check to see that the CCV system is working correctly. Check to be sure the hose is fitting tightly to the nipple at the intake manifold and that it(hose) is not broken anywhere along its length.Check for vac at the valve cover connection.
Also short trips in cold weather will allow the condensation to build up in the oil

Click to expand...

Those are the lines that go from the top of the valve cover to the air filter, correct? Can i just use a liquid leak finder and put it at the connection to make sure it's not leaking? I'll go check the whole hose and make sure there are no holes in it. Should it be like a mailable hose, or should it be pretty unbendable?

How do i check for vac? Just make sure it's sucking at the valve cover?

gradon said:

If your compression is good(done on a warm-up engine), then I'd doubt you'd have a warped head.

Click to expand...

To do this i need to get my engine to operating temperature, then shut it off, remove all plug wires, remove one plug and begin to check compression?

Compression should be 120-150PSI on all 4.0s, correct?

Runnin'OnEmpty said:

I agree plugs look good. The oil also looks OK,
at least on the dipstick.

If there are no bubbles in the radiator, and no
white vapor coming out of the tailpipe when
warm, I'd look further before pulling the head.

The coolant leak could be a heater shut-off
valve, radiator hose, etc. that seeps out and
then evaporates before reaching the ground.

You still could have head problems, but there's
no obvious signs that are showing up...???

Click to expand...

I'm going to go check the tail for white smoke at operating temperature and while i do that open up the rad cap and see if it bubbles at all. I changed out the radiator like a week ago, is it possible that the system is still burping, or any bubbles at this point is something else?

I've never driven a vehicle with a blown HG before. Are the signs super obvious? The jeep runs fine. Sounds normal, etc etc. It's not like studdering down the road hardly pulling itself along.

Tim_MN said:

Coolant loss can have other causes as suggested. Perform a cylinder leak down test to check the head and gasket. By applying compressed air to each cylinder in turn (with that cylinders intake & exhaust valves closed) you can isolate any faulty cylinder.

Have oil tested by a lab for contaminants (like coolant).

White goo on the oil fill cap can be from simple condensation. Make lots of short trips in cold weather ?

Click to expand...

I have no clue how to perform a cylinder leak down test with compressed air. I will use the search function, attempt to figure it out, and report back with my findings.

Once again, thanks for all the help.

Just made a video of the jeep idling. What is that test called where they put the air pump over the radiator cap and pump pressure into the system to see if it's leaking?

Would that tell if i had a problem with the HG or block? Do you think advance auto would be capable of doing this test or have the tool to lend to me?

http://www.youtube.com/watch?v=-3H9T-NB4ww

The cooling system operates at only 16psi. All you would diagnose is a cooling system leak.

You can rent the equipment to perform a cylinder leak down test.

Tim_MN said:

The cooling system operates at only 16psi. All you would diagnose is a cooling system leak.

You can rent the equipment to perform a cylinder leak down test.

Click to expand...

Can that test tell the difference between a loose hose or something like that versus a shot HG or cracked head?

Just called around. Nobody will rent out that equipment and i'm not going to buy it. I have the parts laying around to build one.

All i need to know is what type of thread is the spark plug threads? I need to buy this piece pictured below that screws into my spark plug hole.

All you would diagnose pressure testing the cooling system, is a cooling system leak.

I'd get a UOA. That will be able to tell you if you're dumping coolant into the oil or if it's just condensation.

Other year 4.0s will crack the head too. I almost bought a '96 ,rust free , but passed because it was 2wd. 3 months later, I saw it in the junkyard with a milkshake on the oil cap. I've known a few more people locally that cracked their head on ther 97- ... it's not out of the question.

Miller88 said:

I'd get a UOA. That will be able to tell you if you're dumping coolant into the oil or if it's just condensation.

Other year 4.0s will crack the head too. I almost bought a '96 ,rust free , but passed because it was 2wd. 3 months later, I saw it in the junkyard with a milkshake on the oil cap. I've known a few more people locally that cracked their head on ther 97- ... it's not out of the question.

Click to expand...

Have any recommendations on which company to send my oil out to?