How can I tell if I have the cylinder head that is prone to cracking?
- Thread starter Craig Waite
- Start date
A 2001 4.0L should have the 0331 head that's prone to cracking. The TUPY 0331 head is the improved version. To verify yours, look down the oil fill opening.
I also have a 2001 that I purchased new when I lived in Arizona and from what I gather Jeep had a flaw in the casting that went unnoticed. Some people say they went way beyond 100,000 miles before trouble...few others not as lucky...no way to tell :nusenuse: I'm coming up on 60,000 miles and have stayed on top of maintenance so I'm crossing my fingers while hoping for many more miles!
My 2000 TJ was built in January, 2000 and I took delivery early the next month. I'm hard up on 190K miles now. A few years ago, I had to replace a blown head gasket, but the head itself appears to be OK. However, when I dump a bunch of money into the Jeep soon, I'll put a new head in at the same time. My neighbor and friend does that sort of work professionally.
Is it certain year models that are affected or is it a manufacturing time period? Either way, what’s the time period that is prone to cracking?
Nothing other than changing the cylinder head unfortunately. Unless your cylinder head already has the TUPY casting on it when you remove the oil cap, then you'll know it was an updated (fixed) cylinder head.
Jeep didn't address this problem until the middle of 2002, so many 2002 models are also affected.
Lifted straight six
TJ Enthusiast
Sorry to dig up an old thread. Mine is a 2002 and has TUPY casted into it when I look down the engine fill hole, this means I am “ok” and have the updated head that isn’t prone to cracking. correct?
Metalmoto
Member
210,000 miles on my 01' Sahara so far. Knock on wood.
Bought is used 4 years ago, so I don't know much about the history on it.
I believe engine is original. Was told the auto trans was "recent" rebuild.
Fame was repaired, but whoever it was, did an excellent job!
Only had to replace the radiator, lower steering shaft, and CPS (twice).
Don't buy cheap sensors, or you'll be replacing them a year later.
I do all repairs myself, unless it can't be done without a lift.
Bought is used 4 years ago, so I don't know much about the history on it.
I believe engine is original. Was told the auto trans was "recent" rebuild.
Fame was repaired, but whoever it was, did an excellent job!
Only had to replace the radiator, lower steering shaft, and CPS (twice).
Don't buy cheap sensors, or you'll be replacing them a year later.
I do all repairs myself, unless it can't be done without a lift.
Rustee
Member
Rustee
Member
What exactly are we looking for under the oil cap? I'm having issues with my 2000 right now. Not sure if it's cracked or head gasket is gone.
Rustee
Member
TUPY casting, right? But mine is a 2000 model so it wouldn't have that casting since they starting doing the TUPY casting in 2002? will it have 0331 under there then?
If it says TUPY, it's the newer head. If it doesn't say TUPY, it's the older, crack-prone head. It may say something else, but who cares?
The original head on your Jeep may have been replaced, which is why you should check, regardless of what was in there originally. I think the factory replaced some of the heads under warranty.
The original head on your Jeep may have been replaced, which is why you should check, regardless of what was in there originally. I think the factory replaced some of the heads under warranty.
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