Low Miles, Blown Head Gasket

Beachhead

Beachhead

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Chico, CA
So my TJ which I bought last year started exhibiting coolant use. Id drive a few miles, and the overflow tank would be down. Fill, down again.

Checked compression, was good. Out of ideas I took it to my local shop, they found some leaky hoses, fixed. It is still using coolant. So I take it back and they put the pressure tester on it for 3 days straight, and finally come to the conclusion that the head gasket is blown. There is coolant in the engine oil now.

Basic maintenance like oil changes and coolant I can do, but taking the engine apart is beyond my ability, and time.

This Jeep (2000 4.0) only has 44,000 miles on it. Why would the head gasket be going out already? I'm just wondering if there is more here that I should be looking into.

Thanks
 
Have you looked into the 0331 cracked head issue? Some 0331 stamped heads were prone to cracking which caused coolant loss but otherwise the engine runs fine. You can pull the oil fill and see if you have a TUPY head which supposedly fixed the issue.
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Yes it's an issue now. However, if you order and properly install a head from the link @bromel provided, your worries will be gone and you'll get many miles of enjoyment out of the low miles Jeep you have. Like @TheBoogieman, I've had issues in the past and installed two replacement heads in previous '00 and '01 XJs. They both went on to provide me years of reliability.
 
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Keep in mind any vehicle is subject regardless of miles to overheating possibly cracking the head or smoking the head gasket. Just depends on how it was used and maintained. My personal experiences on numerous jeep vehicles are the OEM radiators are prone to seam failure.
 
It's luck of the draw. I have a 2000 TJ with the original 0331 head and it's fine so far at 120k. I have a 99 WJ with a 0331 head with 165,000 miles and it, too, is fine. Will those heads crack? Maybe, maybe not.
 
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bromel said:
It's luck of the draw. I have a 2000 TJ with the original 0331 head and it's fine so far at 120k. I have a 99 WJ with a 0331 head with 165,000 miles and it, too, is fine. Will those heads crack? Maybe, maybe not.
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Yep, some heads crack, others go 200k with no issue, as it's a casting flaw.

Personally I owned 2 2000 XJ 4.0L's, and replaced the cylinder head in a weekend with the better casting on my own time instead of waiting for it to crack. I figured it was cheap insurance (fortunately I can do it myself) to not have to worry about it. Both Jeeps rusted out before I had any engine issues.
 
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Beachhead said:
Great. So much for the unbreakable 4.0.
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I think its more related to "tried and tested" when compared to other engines Chrysler used.
To some a cracked head or a blown head gasket is the end of the world while for others its a simple repair over a few beers with a mate but at least you know the most likely cause of the problem which is your year was prone to head cracking! another year could have been because it was cooked a few times or from driver abuse.
 
Before you spend money on a new head gasket or head I'd put an oil pressure gauge on it and verify the bearings weren't damaged running coolant. Typically a blown head gasket is caught really early but cracks can let coolant into the oil for months and even years before they are diagnosed leading to some collateral damage.
 
L J said:
I call it the "Under Powered but Decently Reliable" 4.0
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Its called Gas guzzling reliability if it didnt have a computer that made it unreliable!
Or a shit gearbox's! Lets face it, its all about the nostalgia and 4x4 capability and 4x4 has never been as reliable as 2wd anything, even Toyota land cruisers!
 
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Beachhead said:
How can I check if it's one of the 0331 heads? I can't locate the piece posted above.
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From the post above:
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The good heads have TUPY as shown in the pic. They are all 0331s.

Non TUPY heads are crack prone.

Look down the oil fill hole and check for coolant seeping or signs of contaminated oil.
 
Just to be clear, your 2000 came from the factory with a non-TUPY 0331 head. That is what you have, unless a previous owner replaced it with a 2002+ head, which are also 0331 heads but are labeled TUPY to signify the casting defect that caused the cracking was fixed. I can't imagine that is the case, here. You almost certainly have a cracked head, so you need to replace it.

To confirm, you can shine a light down the oil filler cap after turning the hot engine off. Wait a minute or two and see if you can see coolant bubbling up.
 
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