disguay

Bought a 00 cherokee with what I thought was the notorious cracked 0331 head. Discovered the head was not original and had been replaced with the updated TUPY stamped 0331. Now I know my head gasket it pretty badly blown, but I am wondering if my head could also be cracked. If TUPY heads are not known for cracking, I'm just going to throw a new HG in her and hope that deals with the coolant loss. If TUPY heads have been known to crack or warp, then I'm going to have it ported and machined and what not.

Just curious as to what people have experienced with XJ's with the TUPY head swap.

freegdr

If you pull a cylinder head you have it looked at no if and or buts, unless you wanna do it again.

belvedere

for sure

CCKen

When you remove the head to replace the head gasket, it would be a good idea to check the head for being warped. Using a straight edge and feeler gauge check for flatness. If the cylinder head wasn't torqued down properly there's a chance the head got warped.

Flatness . . . . . . . . . . . . . . . . 0.03 mm per 25 mm
(0.001 in. per 1 in.)
Flatness . . . . . . . . . . . . . . . 0.05 mm per 152 mm
(0.002 in. per 6 in.)
Flatness Max. . . . 0.20 mm - max. for total length

(0.008 in. max. for total length)

Use a quality head gasket and you may also need new head bolts since this looks like this may be the second go around on your existing bolts.

I recommend the Victor Reinz gasket and head bolts, available from Rockauto.com.

Make sure you go by the torque sequence specified in the FSM.

pdowty68

Any head can crack, especially when overheated, the head could be warped too

RTorrez1

I was going to say the exact same thing! It doesn't matter what kind of head you have. If you over heat it you can crack it.

Firestorm500

Yeah, I had one that was cracked between #3 and 4, sideways across the head on a '66 Mustang 200 CID.

It was found during a rebuild.

They are not known for generally having problems cracking, but as others have said, anything can do it.

disguay

thank you all for your advice. I checked the head for flatness and it fell in spec. While doing the head gasket I bought the VR complete gasket set to do it right in addition to Fel-Pro head bolts which were all torqued to spec except for #11 which was torqued to 100ft/lbs due to the coolant interference.

To all the others out there that are reading this, the TUPY heads are much more resilient than non-TUPY 0331 heads, yet the TUPY heads still run the risk of cracking in the common area between #3-4.

Also, after replacing the head gasket, I ended up blowing the water pump immediately after due to the increased pressure in the cooling system that could no longer be discharged out the bad head gasket.

Larry's XJ

I was going suggest checking the pump/thermostat

BlueRidgeMark

One more time. ANY head can crack.


It doesn't matter if it's a "known" problem or not.

Any head can crack. Ford, Chevy, Detroit Diesel, Rolls Royce, BMW, whatever. It doesn't matter.


ANY head can crack.

cruiser54

Not if you ask enough times!!!!

jebmccall

have a brand new cummins 15 litre in the shop with a cracked head at 4500 miles..... so yes any head can crack could be a casting defect.....

5-90

Nothing is impossible, but I've not heard of a TUPY cracking yet.

But, I've got a 0630 that was never overheated (per donor,) with radial cracks around five of the twelve valve seats... Only 0630 head I'd heard of that's cracked.

bigbadon

Pull the head and inspect the head gasket...if it is blown you have found the problem. Unlikely both would be bad but you can have the head inspected by a machine shop.