94 4.0 overheating problem and whats the next step?

[Red Thunder]

I recently bout a 94 4.0 ranger with 150,000 miles. I soon discovered that the engine runs hot, and frequently overheats. I had it looked at, and the mechanic told me one of the cylinder heads is cracked and is allowing air to enter the cooling system causing a vapor lock. Taking into account the age of the engine, is it worth changing just the heads or should I consider a swap?

 

[Josh B]

What evidence did he provide? Are you sure it isn't a stopped up radiator? I found mine to have a blind spot which can't be seen by normal means, almost requires pulling it out, which I did only after mine began to leak and replaced it. Near the bottom at the front (that part is hiding behind the AC Evaporator) it was so stopped up with old dirt was hard to believe

 

[enginepaul]

I recently bout a 94 4.0 ranger with 150,000 miles. I soon discovered that the engine runs hot, and frequently overheats. I had it looked at, and the mechanic told me one of the cylinder heads is cracked and is allowing air to enter the cooling system causing a vapor lock. Taking into account the age of the engine, is it worth changing just the heads or should I consider a swap?

There is a misunderstanding here because vapor lock is a fuel delivery problem. If air is getting in, then steam (or water) is getting out when it is warmed up. I'd guess water pimp and/or radiator. Drain your radiator and look at the coolant as it come out for starters.
People are sayig the 4.0 can last 300,000 miles but we don't know how yours was maintained or driven so I can't help on the replacement question. (I'm in the San Francisco Bay Area so I spend a LOT of time at idle and stop and go traffic so 150,000 is a lot to me.)

 

[Uncle Gump]

Do the glove test... search it on the site.

I've always tested with a pressure tester... look for a steady climb in pressure... or blowing up the latex glove. That would indicate combustion chamber pressure leaking into the cooling system.