Jeep Cherokee Forum - Cylinder head

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- - Cylinder head (https://www.cherokeeforum.com/f2/cylinder-head-250069/)

Hey guys, so I went to do an oil change yesterday and notice a lot of sludge in my cylinder head. I have a 1990 XJ that i bought used, and I've notice that the cylinder head has the 0331 stamp. I know this is the one that is notorious for cracking between #3 and #4, but I thought they were only used in the 99-00 models. Anyway I'm pretty sure its cracked and coolant is seeping in. So I want to buy a replacement head, but dont know what to buy? Im not the best at mechanics so I dont know if there had to be mods done to fit the 0331 in my jeep in the first place. Is it possible that I could just get the reinforced 0331 from Clearwater, and it would fit the same as the old 0331? Or should I be trying to find the head made for the 90 renix?

The 0331 problem was 2000-2001, maybe some 99s.

https://www.cherokeeforum.com/how-to...rmation-398176

These also didn't have distributors anymore, so IMO stick to a straight up replacement.

Well I have a 1990 with the 0331 head and its cracked. There's a lifter tick and sludge build up. I just want to know if I can get the 0331 Clearwater replacement head. I must be able to since the 0331 is in the truck right now

Can you actually see the crack since you have the valve cover off?

Quote:

Originally Posted by Jamrock37 (Post 3544658)

I suppose you could, but why? I would get a straight 1990 replacement head. TTBOMK your engine should have had a 2686 head. I think somebody pulled a fast one on you!

Oh wait-- what's the serial number of the engine?

Do you have a distributor or coils?

Quote:

Originally Posted by lawsoncl (Post 3544664)

Can you actually see the crack since you have the valve cover off?

Certainly the best place to start (find out what needs fixing before you try to fix it).

OP previously posted that he has a distributor, so the engine is a hybrid. The 0331 head could be a bad 0331, a good 0331 (TUPY), or even a Clearwater et al.

And cracked or not. Could just be a head gasket.

IMO OP needs to identify block:

Quote:

Originally Posted by cruiser54 (Post 3360289)

4.0 Engine date codes

The date code is on the passenger side of the engine, on the block, just forward and up from the distributor on a machined flat surface.

The digits of the code identify:
 1st Digit-The year (8 = 1998).
 2nd & 3rd Digits-The month (01 - 12).
 4th & 5th Digits-The engine type/fuel system/compression ratio (MX = A 4.0 Liter (242 CID) 8.7:1 compression ratio engine with a multi-point fuel injection system).
 6th & 7th Digits-The day of engine build (01 - 31).
1. FOR EXAMPLE: Code * 801MX12 * identifies a 4.0 Liter (242 CID) engine with a multi-point fuel injection system, 8.7:1 compression ratio and built on January 12, 1998.

If the existing head is bad, find out what head is SUPPOSED to be there.

Then find out what mods (if any) were done.

Then review options, perhaps considering going to 7120s.

And if original owner knowingly put a crap 0331 on there, you need to take your crowbar and do a Marv on him.