Purchased a 2001 Cherokee Limited some time ago and wondered if there was a way to look at the engine and determine if it still has the 0331 or if it has been replaced?

 

http://www.naxja.org/forum/showthread.php?t=1053502

 

Should be able to take the oil cap off and look right inside to see the TUPY casting, if it was replaced with a 0331 series.

If it was replaced with a non-0331 head (unlikely), you can find the casting number just below the middle of the injector rail, partially covered by the valve cover.

 

The 2000 and 2001 came with the original casting 0331 head. The TUPY head was also a 0331 head that had been redesigned with a thicker deck. You can also buy an aftermarket 0331 head from Clearwater that has a thicker deck to prevent the cracks. All three of these are are 0331 heads because of the design of the ports, and all three of them have "0331" cast into them in the same spot.

If it's been replaced, there's a high probability that it has been replaced with an aftermarket 0331 head that has been redesigned with a thicker deck to prevent cracking. What you want to know is whether you have the original 0331, an aftermarket 0331 or a 0630 head from a '99 or prior.

For the casting number, look on the driver's side of the head near the center, and you'll see a number peeking out from under the valve cover, like so:



Again, the original will have this number, and the replacements with the fixed deck will also have this number. The only way you won't see "0331" there is if someone has swapped in an earlier head.

To find out which 0331 you have, shine a light down in the oil filler cap and look at the surface of the head between the #3 and #4 cylinders. Below is a pic another member here posted a while back of an original 0331 on the left, and a Clearwater 0331 on the right.



You'll notice that the Clearwater head (right) has a number cast into it between the #3 and #4 cylinders, near where the original 0331 liked to crack. The original 0331 (left) has nothing cast into that spot.

A TUPY head will have "TUPY" cast into it right there, like so: