Should I avoid the 0331 head?

[Travis Connell]

Hey guys, I’m new to this and looking to buy a TJ. I’ve seen a lot of posts about the 0331 head and I just was wondering how common the problems with them really are. I’m going to look at a 2001 Sahara with 41,000 miles this weekend, if it has the 0331(which I’m guessing it does) should I just walk away? If I do get one with the 0331 is it a ticking time bomb that I should look into replacing ASAP? Or will it be fine if it’s taken care of? Do the majority of them have problems or does it just seem that way online?

A few weeks ago I knew almost nothing about Jeeps, thanks to you guys on this website I’ve learned so much. People like all of you, are a huge reason why I want a Jeep. This community is honestly the best, there’s not another one like it. Thank you guys so much!

 

[Chris]

Hey guys, I’m new to this and looking to buy a TJ. I’ve seen a lot of posts about the 0331 head and I just was wondering how common the problems with them really are. I’m going to look at a 2001 Sahara with 41,000 miles this weekend, if it has the 0331(which I’m guessing it does) should I just walk away? If I do get one with the 0331 is it a ticking time bomb that I should look into replacing ASAP? Or will it be fine if it’s taken care of? Do the majority of them have problems or does it just seem that way online?

A few weeks ago I knew almost nothing about Jeeps, thanks to you guys on this website I’ve learned so much. People like all of you, are a huge reason why I want a Jeep. This community is honestly the best, there’s not another one like it. Thank you guys so much!

See here:

https://wranglertjforum.com/threads/how-to-identify-0331-or-tupy-head.8112/#post-117209
If it's the updated head, no need to avoid it.

I have owned a Cherokee XJ with the 0331 head (non TUPY) and it cracked. So yes, I would avoid them. They are problematic due to the bad casting.

 

[Travis Connell]

Im gonna look that over right now, thank you so much for your help!

 

[bromel]

Enough crack that it's a problem, but most probably don't. There are so many high-mileage Cherokees, TJs and WJs out there with the 0331 head that haven't cracked yet. I have a 2000 TJ with 111,000 miles and a 99 WJ with 150,000 miles, both with the 0331 head, and I've had zero problems. But I monitor my coolant like a hawk. Worst case, you buy a new head for $500 and find some fairly skilled friends to help you.

I would not avoid a 0331 non-TUPY head, but you should be vigilant and prepared that they could crack at any moment. They aren't like Cadillac Northstar engines in that they are *guaranteed* to blow a head gasket—I know guys with 300,000-plus miles on their original head. I also know guys who take care of their 4.0, never overheat it, and the head still cracks. It's luck of the draw.

 

[Jerry Bransford]

If the engine runs well I wouldn't worry about its 0331 head. If it ever gives you a problem obtaining the better TUPY head will not be a problem.

 

[Davidtj]

If you get it and it cracks might give you the opportunity to try this

https://www.edelbrock.com/performer-jeep-4-0l-cylinder-head-50169.html

 

[Vasq]

I've got 235k on a 0331 head and it's fine. And like Jerry said, if it ever rears it's ugly head its easy enough to get parts and replace it. If the jeep is clean in all other regards i wouldn't let that scare you away.

 

[Jerry Bransford]

If you get it and it cracks might give you the opportunity to try this

https://www.edelbrock.com/performer-jeep-4-0l-cylinder-head-50169.html

Are you running one? That product is not compatible with the 1999 and newer 2-piece exhaust manifolds. Not to mention I wonder if its higher compression wouldn't require timing changes and that it would likely require 89 or higher octane gasolines. Personally I would consider a high compression head as a potential bunch of issues getting it working well.

 

[Vasq]

https://www.cylinder-heads.com/product/new-jeep-cherokee-laredo-4-0-0331-cylinder-head-complete/

 

[Davidtj]

Are you running one? That product is not compatible with the 1999 and newer 2-piece exhaust manifolds. Not to mention I wonder if its higher compression wouldn't require timing changes and that it would likely require 89 or higher octane gasolines. Personally I would consider a high compression head as a potential bunch of issues getting it working well.

Not running one. Maybe at some point someone on form will test