Hi all,

About a month ago, my 2000 Cherokee 4L/6 had a pretty nasty overheat, jumping from 220 to 250. We thought at the time it might be due to a bad radiator cap, and, after replacing it, the engine ran just fine.

That is, until a few days ago. While stuck in traffic on a mountain pass, the car jerked hard (while at a standstill), then the temperature started increasing again. I pulled it over and found the coolant tank bubbling and some coolant coming out of the overflow. After letting it cool down some, we drove it the rest of the way home once we found the temp stayed pretty steady at 210. Took it into a shop, and they found the radiator cap wasn't holding pressure, and found the presence of hydrocarbons in the coolant. No observed crack within the oil valve, however the coolant appeared milky.

Based on some info I've seen around this forums, these symptoms are pretty indicative of a cracked cylinder head. I wanted to ask - how difficult is it to replace the cylinder head on your own? And, should I buy one new, or are there any heads from older (or newer) models that are recommended to replace the 0331 casing, that I could just pick up from a junkyard?

- Everett

 

Overheat on a 2000 followed by milky oil = likely cracked head. You might be lucky and it's just the head gasket, but I'd replace the head anyway since that casting was know to crack.

 

People have done it singlehanded, but it's a heavy old piece of cast iron - so, for that reason alone, it's better if you can get some help.

You need to be very careful with a used head, from any source, both as to identifying it & being able to assess its condition.

Good luck, on both counts.

 

I prefer to remove the hood and use a overhead pulley setup to pick and place the head. Much more control than man-handling that 80 lb chunk of iron by yourself. A couple of cutoff and slotted head bolts really help getting it lined up and set in place without damaging the head gasket. Don't put the guide bolts in the back or go too long as you need to get around the top of the firewall in the back while maneuvering it into place.

 

Genius! I’m glad I saved the old head bolts and I will do this soon when I get the TUPY head back from refurbishment.

To the original poster (OP), located a used head from car-part.com that is near you from a 2002+ 4.0 motor from a Grand Cherokee or Wrangler. It will have “TUPY” raised letting on the top of the head as viewed down from where the oil cap would be on the valve cover. I paid $150 for mine plus $40 for a ground courier to bring it from the junk yard to the machine shop. Then it’s like $100-200 for them to clean it, inspect it for cracks, and pressure test it.

 

Some good info in here - thanks all. I'll take a look around local junkyards, see if I can find a '02 or '03 Grand TUPY head - may just pick up a new unit otherwise.

That said, does anyone know if the #7120 casing is a direct replacement?

 

It is not. Different intake and header would be needed and you would have to figure out how to mount the coil rail.