Hey everyone. New to jeep in general but in the next week or so I will be getting rid of my '13 wrx and hopefully getting a 99-01 xj. Plan is to be a dd with just enough done to have some fun on the weekends. I am choosing the xj because of the high reputation they have of reliability.

 

Welcome to the forum.

Just a heads up, very late 99-01 have known issues with the cooling system, especially the 0331 heads. Do research on that before buying anything

 

How do you tell which heads a xj has?

 

The casting number is cast on the head on the driver side of valve cover. Near the oil fill cap.

You should see the markings such as this one






99 has either 0630 or a 0331 heads. Thankfully my 99 (July mfg date) had a 0630 head.


In the picture the valve cover has been removed, but you aren't required to remove it in order to see the casting number.

Sometimes oil or grime would cover it up, u just need to wipe it away and u ll see the number.

NOW, just if because u saw a 0331 doesn't mean it's automatically no good. You have to check the oil if it's milky color, shine a flashlight down the valve cover and see if there is any greenish tint. With the engine and radiator cool, take off the radiator cap and start the engine, and either listen or wait for smell of exhaust coming out of radiator.

If the seller allows you, u could do the cylinder compression test.

Question the owner if the engine has ever been overheated in the past.

Some members here on the forum has gotten their xj or WJ over 200,000 miles on the original 0331 heads, with extreme care and maintenance, it's possible.

 

If you love to wrenching, has plenty of junkyards around you, and don't mind new projects. U could find a 0331 TUPY head from a 02-04 grand Cherokees (WJ) or a 02-06 wranglers (TJ). And then replace the head.

That's what I did with my 2001 cherokee.

 

What XJ said!

I think the 99 might be the best year if it doesn't have the 0331 heads.

Also check it for rust thoroughly!

Welcome!