blown head need advice?

i have a 2000 xj 4.0 had block test done failed runs good uses little water. Any body know if its ok drive as long as watch the temp.

The 2000 models are notorious for suffering from cracked heads. Remove the oil filler cap, peer under the valve cover, and look for telltale signs of chocolate brown sludge which would indicate coolant getting into the crankcase via a crack in the head. The most common site for cracking is in the middle between the no.3 and 4 cylinders.

Yep it is a casting flaw in the head to which Chrysler has so far never admitted fault. So what to do?

We've all been there. Human nature makes us tend to not want to have to deal with something as expensive or as labor intensive as a head replacement. So we say to ourselves "OK, I know the head is cracked, but the engine still runs OK, so if I watch the temperature gauge I can defer the work or expense a while". Or "yeah, the needle is in overheat but I just need to get to the next exit."

Problem is, your temp gauge is a somewhat delayed indication of what is actually occurring in the block. If you are cruising down the interstate at speed and you see it begin to rise, the engine block overheat event is already happening and that temperature is more than the indicated temperature you are seeing on your instrument panel.

There are lots of posts on this board from guys who have run a cracked 00 or 01 head for some time (six months or more). But there are also lots of posts from guys who tried and trashed their engines. Bottom line, you are now gambling with a problem you know can get a lot worse for your entire engine. In the immortal words of Dirty Harry, "Do you feel lucky?"

My advice is search the posts on the "how to" install a 97 or 98 head on your 2000. It's not exactly the same as your head and requires some mods. Worth the effort. If you put on a late 99, 00 or 01 head, history will repeat. Get it fixed as soon as you can.

Don't bother with an earlier head. Too many compromises and hoops to jump through in the intake and exhaust manifold area. Get a used 2003+ head and have it checked out by a machine shop or get a new after market one that has been strengthened. Both will be direct bolt ons.

Also, stop driving it as coolant + oil = acid to bearings.

There's also a company called Clearwater Cylinder Head (727-299-9058 or eBay) that offers a new design casting (not used or rebuilt) that will bolt on.

Talyn said:

Don't bother with an earlier head. Too many compromises and hoops to jump through in the intake and exhaust manifold area.

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The main problem with using an earlier head is having to use an earlier exhaust header and having to modify the downpipe. That's an issue if you have a 2-into-1 downpipe with precats. You also need to fabricate mounts for the coil packs.
Nowadays there are more junkyard '02+ TUPY heads to choose from and these reinforced castings are seemingly problem-free.

It is still an issue if you don't have the precats. Sure you don't have to worry about the cats, but the down pipe will still have to be modified if you go with an earlier header.

Actually, I forgot to mention that you can use an earlier head with a later aftermarket header with out issue. That eliminates the issue of modifying the down pipe or eliminating the cats. You still have the could rail support to deal with, but that is a very minor issue.

Sand-Dog said:

There's also a company called Clearwater Cylinder Head (727-299-9058 or eBay) that offers a new design casting (not used or rebuilt) that will bolt on.

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I swapped one of these heads on my 99 and was impressed with their quality. If you can't find a good cheap replacement locally I highly recommend it.



This is the center of my old 6280 head, shown for comparison.


The new aftermarket casting:


Intake:


Comb. chamber is a little rough, but typical for most Iron heads.

Sand-Dog said:

There's also a company called Clearwater Cylinder Head (727-299-9058 or eBay) that offers a new design casting (not used or rebuilt) that will bolt on.

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3rd recommendation for Clearwater. I threw one on my '99 when I rebuilt the engine. It is a NICE piece.

notamos said:

3rd recommendation for Clearwater. I threw one on my '99 when I rebuilt the engine. It is a NICE piece.

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Did you notice any difference in power in between the 0630 and the 0331 head? Just asking since the 99' XJ's got the 0630 head with the newer style intake manifold.

streetxj said:

Did you notice any difference in power in between the 0630 and the 0331 head? Just asking since the 99' XJ's got the 0630 head with the newer style intake manifold.

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my (august) 99 has a 0331 head.

GrimmJeeper said:

my (august) 99 has a 0331 head.

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Oh okay. So it's a 00' model made in 99'. I understand now.

streetxj said:

Did you notice any difference in power in between the 0630 and the 0331 head? Just asking since the 99' XJ's got the 0630 head with the newer style intake manifold.

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I doubt there would be much of a difference, although the 0630 does have larger exhaust ports. The primary benefit is that it's simply a good strong and well built replacement.

Clearwater is by far the best choice if you have the funds for it. But if you're strapped for cash like I was, older heads are fine to use without changing the downpipe a bit, I have a 1999 motor in my 2001 with the 0630 head. I used my factory manifold/downpipe/pre-cats with the manifold gasket from my year and about half a can of copper gasket spray, no leaks. The only thing you need to do is make a mount for your coil packs.

Isn't Clearwater and Titan the same companies?

Nope. One is in Ocala Fl, the other in Clearwater FL

I put an Alabama Cylinder Head unit on my 2001 a couple years ago. Works fine and decently cheap given what it is.