Ok so I just got my xj all put back together. Replaced the head gasket on it. Just started it up tonight, and it overheats now. Never got above 210 before it was taken apart. Every surface was cleaned thoroughly. Any ideas on where I should start first? Thanks

 

Possibly got air in the system

 

The thing heated up in less than 5 minutes and it is about 30 degrees out here. I don't know what the deal is with it.

 

Sounds like you got air in the system. What year XJ is it

 

It's a 93, 4.0. I just hope it is something simple. I filled the coolant tank to the full line, but didn't remember to put it in radiator. Then ran it and it heated up. Then put some in radiator. Before I put any in radiator though the coolant tank was bubbling but wasn't emptying.

 

So you have an open system (rad cap). You need to make sure the rad is full. Otherwise you'll get air in the system. The plastic bottle is the overflow.

 

Alright thanks. I was so excited to get it running again, and then this happens haha.

 

Just fill your rad. Make sure it's all the way full with no air and you should be good

 

I'll try that tomorrow. Thanks, I appreciate it.

 

Wait wait.... hold on a sec.


You started your XJ up without putting ANY coolant in the rad?? So basically, the entire block was dry? And you let it run for MINUTES that way?

 

No, it had coolant in it. I didn't drain it completely.

 

Ok good. Lol, I was about to say, but as long as you had some coolant in the block, rad, and overflow. But I do agree with the above posters. Have you had different results after filling the radiator? Keep topping it off because air pockets are notorious on the 4.0. Aso, where did you get your t-stat from?

It's a long shot, but I did a t-stat replacement a while back with an autozone unit. For some STRANGE reason, even with everything installed properly and correctly, the t-stat would not open. It was a dud right out of the box.

 

I've had the same thing happen with t-stats. It sucks. Yeah tonight when I got home I unhooked the heater hose I think it was from the thermostat housing while filling the radiator. It took about another gallon of coolant. Damn thing tricked me into thinking it was full last night. T-stat is same from before the tear down, I didn't take that housing off.

 

Also, I'd like to thank everyone again