96 JGC Slight Overheating-Cool Air

[JenCO]

My 96 JGC is (all of a sudden) running up at about 230 degrees and the heater is blowing cool air. Although, for a few mionutes on my way home, the heat came on-hot-and the temp dropped to 195ish (normal), but then went back to cool air, hot engine. Engine sounds good, but is leaking small drips from the radiator (I think). I thought it was thermostat, and changed that, but nothing changed. I did notice that when I took the top hose off to get to the thermostat, that it was dry. Any ideas?

[leowolf]

theres a lot of dangers when working with cooling systems, they can cause blindness and permanet disfigurations from burns, dont mess with them unless you are qualified.
Check the weap hole on the water pump, change the radiator cap. fill the cooling system to the top when its cool, take it for a spin and inspect the entire system for leaks.

[dksob81]

sounds like you have an air posket in the cooling system, when the engine is cold take the radiator cap off and make sure the radiator is full (50/50 coolant mix) if not fill it up then also make sure the coolant reservoir is filled to the ADD mark (not FULL mark), then start the engine and let it run for about 20 seconds and remove the radiator cap (with engine running) and refill if necessary, do this about every 20 seconds about 4-5 times, if it starts to spill out while loosening the cap just retighten it and wait longer and try again, if happens again the coolant system maybe full of coolant. the shut engine off and let sit for awhile to completely cool the engine, and recheck the coolant level in the radiator and reservoir.
DO NOT CHECK THE COOLANT AFTER RUNNING THE ENGINE FOR A LONG PERIOD OF TIME (5 or more minutes), THE COOLANT WILL GET HOT AND EXPAND AND WHILE REMOVING CAP SPRAY EVERYWHERE AND CAN CAUSE HARM.

THIS SHOULD FLUSH OUT THE AIR POCKET AND GIVE YOU HEAT BUT NOT OVERHEAT ONCE AGAIN.

if this does not work check to make sure the Thermostat is operating correctly, after running the engine to get it to normal operating tempature, place your hand on the upper radiator hose, it should be hot, if it is not, shut the engine off and wiat about 5 seconds and recheck upper radiator hose, if it's still not hot then either the thermostat is not opening or the thermostat is stuck open - remove the thermostat and check to make sure nothing is jammed in it keeping it open.

[JenCO]

thanks! dksob81 for the input- turns out there is a gash on the inside of the radiator so once I started filling it with the cap open, ran the air out, I saw the continuous leak- I'm putting a new radiator in this wknd. - bummer.

[dksob81]

if u need a radiator call Radiator Express, they are way cheaper then any other place you will find, I just bought one for my 94 ZJ 5.2L and it only costs me $175. the local rad shop wanted almost $300 for one

[JenCO]

thanks! got one!