I have an 01 XJ with the usual cracked 0331 head...

I got a replacement motor out of a 2000 with around 110k on it in good shape.

My question is, do I find a 0630 head and get an aftermarket header, or can I run the 0331 thats on the motor with a low temp thermostat and a flowcooler high flow water pump?

Thanks for the help guys!

 

I'd run the head you have with a stock thermostat. Running a lower thermostat temp doesn't mean the engine will run any cooler. If that head cracks, which it may likely never do, then consider your options for a replacement.

 

With the probability of another problem down the road since there are known issues with these heads, I would fix it once.

Someone told me in another thread to find a 03 or newer TJ or WJ with a Tupa casting. Whatever that is.

 

TUPY...a Brasilian foundry that casts the heads

If there's nothing wrong with the head on the replacement engine, you can use it...but make sure your cooling system is in prime condition. That said, I am also of the mind to replace it now, while everything is out and easily accessible. Those heads are prone to cracking, as stated and as you have found out with your old engine, it may cost a little more right now and take some more time to do, but if it were me, that's what I would do. Remove the weak link while you can.

 

get rid of that 0331... ive even had 0630's crack

 

Appreciate the intel guys!

 

How do you know that the head in the replacement engine is not cracked? Others may disagree but 00-01 heads fall in two categories: ones that have/are cracked and ones that will crack sooner or later.

 

The guy I got the replacement motor from said it ran well, no coolant in the oil, and good oil pressure. At this point I'm just going to replace the head as a precaution. Don't want to do this again!