Dry head

SO a little background, 1990 4.0, closed cooling system. ive been having overheating issues for quite some time.... figured it was an old clogged radiator... whatever... It was controllable via the defraust + reving the motor while stoped in heavy traffic. Its recently gotten a new water pump, thermostat + housing.



So i took it out, drove the hell out of it out in Hungry Valley, running hot the whole weekend, . eventually, it wont burp.... NOTHING is coming out of the burp hose. eventually it puts a crack in my radiator bottle, thinking nothing of it, i leave the jeep, run home and grab a radiator, cap + bottle, and heater valve ive been meaning to install.... figuring a new bottle, radiator and heater valve will set me up proper. Wrong. After the install, the heat goes straight up, still wont burp... SO i goto check the thermostat, and the head is dry. Nothing in there but heat and a little smoke. I left, came back monday after work with a uhaul, and trailered it home.

Im thinking a clogged coolant passage somewhere in the head? what about the hoses? This is a high mileage vehicle.

can anyone recommend where to start?

new or freshly installed items:
wp
radiator,
thermostat,
heater valve from autozone, leaked from the minute i installed it...
thanks

I had the same problem on a small block chevy. To fix it I took the thermostat housing and the thermostat off and filled the engine itself with coolant, put the thermostat and housing back on and filled the rad up with coolant. It worked excellent after that. Hope that helps, best of luck.

The engine on my beater was the same way when I got it. The heater control valve was blocked up and the trapped air was preventing coolant from flowing. I flushed out the heater hose with a garden hose, then did a couple of chemical flushes, and haven't had a problem since. Make sure to run the heater on full heat when you do this so that the valve is open and the heater core gets hit too.

xjcjfreek said:

I had the same problem on a small block chevy. To fix it I took the thermostat housing and the thermostat off and filled the engine itself with coolant, put the thermostat and housing back on and filled the rad up with coolant. It worked excellent after that. Hope that helps, best of luck.

Click to expand...

a friend of mine had a mechanic do the same thing to his jeep. I couldnt beleive the fix was this easy, as i was positive if the head was dry, there has to be a reason, but i will try this, might even lift the front end of the jeep to get extra juice in there.


thanks to you both for your contributions

How did you refill the system when you changed the radiator. I always fill through the upper hose and have never had a problem.

FYI---the heater control valve is not necessary and should have nothing to do with how hot or cold the engine runs.

to jess no the heater valve does not do any thing to get the engine hotter or colder but when it is overheating if you put the heat on and the fan on high it will help cool down the engine a bit.

and if you loosen the temp sensor on the back of the head it helps get the rest of the air out of the system. you kind of bleed the air out.