Bought my 99 Cherokee with a bad head gasket. Had the head cleaned, tested and rebuilt for a total of $520. Also replaced radiator, water pump and thermostat. Ran great after installed, cooling system worked perfectly! Never went above 210.

2 weeks later I decided to add R-134 to the A/C system. After 15 minutes or so with the engine running as I was charging the A/C I checked to feel how cold the A/C was and discovered the engine temperature was very high. Almost in the red. Turned off the engine and then in climbed into the red. I think the electric fan decide not to go on when I was charging the A/C. Why, I don't know!

Been driving it for the last 2 weeks and discovered I'm losing radiator fluid. There's a crack just below the valve cover oil fill cap. Its cracked the same way a 2000-2001 0331 head would crack. This is not a 0331 head, its a 1999 and older 0630 head.

My questions are

Should I have the head professionally welded and how much would it cost?

Will I need to have the head completely rebuilt after I have it welded? If the answer to this question is yes its not worth rebuilding.

Should I junk my 4 week old $520 head?

 

The shop that rebuilt (tested) the head should be held accountable for the crack. They should have found it when they tested it.


They'll lie and say it wasn't cracked when they checked it but it's worth a try to shove it up their ****.

 

If exposed to a high enough temperature or lack of coolant any cylinder head(s) and or engine block can crack. A pinned and welded cylinder head may not be the best approach at repair when you can buy new for better piece of mind. Any exposure to coolant is extremely detrimental to engine bearing material so engine replacement is another possibility to look in to.

 

I'm assuming it cracked 2 weeks after installed, when it overheated.

 

While the timing is very close to when the head is rebuilt, it seems more likely than a fan clutch or auxiliary fan problem caused the overheat. The two things you do not want to do is continue to run an overheating engine and continue to run an engine that is leaking significant coolant into the oil. I am not sure what year the A/C fan operation changed, but I can tell you that later XJ's such as the 2001 did not always run the aux fan with the A/C. Prior to the change, aux fan would operate whenever the A/C compressor was on or coolant temperature reached 218F. Make sure you connected the aux fan cable after putting the engine back together and that the relay works. The fan may have just died. You can jumper 12V to it to see if the motor runs. If the fan clutch is original or more than a couple of years old, it may not spin the fan well enough to keep the engine cool, but still past most tests you read about. I would talk to he shop and probably end up getting another 0630 head rebuilt...

 

When I dropped off the valve seals at the machine shop he had the head in a pressure test machine (I think that's what its called) and he said it passed the test, no leaks.

Engine does not overheat. Stays firm at 210 in traffic and on the highway. Fan comes on whenever the A/C comes on. Why it overheated when I was charging the A/C I don't know. I don't remember seeing the fan run when I was charging the A/C.

Part of me wants to salvage this head but I don't see how this is possible. I understand what it takes to weld a head and it seems like it would be expensive and require re-machining.

Its very frustrating. I've put a lot of time and money into this thing.

I do have a solution. Friend of mine has a 1999 XJ Cherokee parts Jeep (front end accident damage) with 131,000 miles on it. I'm going to put his engine in my 1999 XJ. Funny thing is my 1999 Cherokee has 131,000 miles on it as well. When I get the motor out of my Jeep I'll check the lower end with a plastic gauge kit. If its good I may sell it or keep it as a backup motor for my newly acquired 2000 XJ which also has a bad head gasket.

 

The head could be fixed but its probably cheaper just to replace it.

 

X2

 

I thought most shops install the overheat disc on the freeze plug on the back of the head that melts at 255 degrees. Mine did from j & C enterprises. When overheated or removed it voids the warranty.