[AzTJ]

If the radiator is cracked, the cap wont releave anything because of the crack already releasing the pressure. The normal temp for a 4.0 is 210... and the temp is picked up buy a sensor near the thermostat housing. Its a 2-wire plug in I believe. I don't know of a way to test it, but it sounds to be working fine. The steam was prolly from the crack in the rad splashing a little coolant out. Replace the rad and you should be good.

 

[Sahara97]

If the radiator is cracked, the cap wont releave anything because of the crack already releasing the pressure. The normal temp for a 4.0 is 210... and the temp is picked up buy a sensor near the thermostat housing. Its a 2-wire plug in I believe. I don't know of a way to test it, but it sounds to be working fine. The steam was prolly from the crack in the rad splashing a little coolant out. Replace the rad and you should be good.

I was thinking that the reason why it cracked was because of the thermostat being stuck closed. I ment that it was wierd that the cap didn't release the pressure instead of the top of the radiator splitting... the spring on the cap wasn't stuck it moved freely

 

[AzTJ]

just because the rad cracked doesn't mean it was under pressure. Just being and old rad, and having platic end caps is enough for them to crack like that. Its a typical thing.

 

[jjseel]

Happened to me, right after I bought mine. I got a new one and put it on. I would have probably done differantly, had I been a member of this forum at the time, I probably would have gone after market. I know that this is probably no help to you, except to let you know that there are people here that can explain things (that have already been there and done that) that will help you save money and labour in the end. Before I got into JEEPS, My neighbor who was a Jeeper, was having the same problem, and we put a thermometer in the neck of the raditator and checked the readings of the gauge. (and made sure we burped the radiator).