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Engine + Driveline / Cooling Questions
« on: July 18, 2009, 06:19:36 PM »
I chased an overheating problem all the way down the to head gasket. Hopfully some of the grief I went through can help you out.
Fan clutch test:
As car starts to over heat, run cool water from a garden hose across the radiator. (Radiator is clsoed all you do is spray water across the fins.) If the water pulls heat out of the radiator and allows the car to cool down its your fan/fan clutch.
Aux fan test (worth doing but probably not your issue):
Disconnect the temerapture switch connector mounted on the side of the radiator. Use a paper clip to jumper the leads. Start the car turn on the A/C (compressor and cabin fan). There are only three leads (ie. three combos for you to jump with the paper clip). Try each: one will drive the aux fan at full speed, one will drive the aux fan at low speed, the other will do nothing. This will tell you your aux fan works and it can tell you if the temp switch is bad (fan works in the test but not at temperature with the AC on).
Easier bleeding:
Place an asprin in the T-stat before installing. This keeps it craked open a bit so you can fill the block easier. When the car heats up the pill will disolve and allow the T-stat to close normally. You can also buy them with a small hole in the top or drill one in yourself. Jacking up the car as you said also helps. Be sure to turn the heater controls to full hot when filling so coolant can reach and fill the heater core.
Is it your headgasket?
My car would over heat at low RPM. I rev it up to past say 2500 and it cools down. Huh??? Turns out gases from combustion chamber were getting into the coolant system creating an airbubble at the top of the system. Spinning the water pump really fast forces water up into the head to cool it back down. (Just got the head back from the shop and miraculously it was not warped). Another symptom was no heat from the heater core at low RPM but had heat at high RPM.
Easy coolant draining:
Use a 6" by 1/2' ID hose from the drain to your pan to reduce the mess when draining the radiator.
Water pump:
If swapping the water pump get the one with a metal impeller.
Fan clutch test:
As car starts to over heat, run cool water from a garden hose across the radiator. (Radiator is clsoed all you do is spray water across the fins.) If the water pulls heat out of the radiator and allows the car to cool down its your fan/fan clutch.
Aux fan test (worth doing but probably not your issue):
Disconnect the temerapture switch connector mounted on the side of the radiator. Use a paper clip to jumper the leads. Start the car turn on the A/C (compressor and cabin fan). There are only three leads (ie. three combos for you to jump with the paper clip). Try each: one will drive the aux fan at full speed, one will drive the aux fan at low speed, the other will do nothing. This will tell you your aux fan works and it can tell you if the temp switch is bad (fan works in the test but not at temperature with the AC on).
Easier bleeding:
Place an asprin in the T-stat before installing. This keeps it craked open a bit so you can fill the block easier. When the car heats up the pill will disolve and allow the T-stat to close normally. You can also buy them with a small hole in the top or drill one in yourself. Jacking up the car as you said also helps. Be sure to turn the heater controls to full hot when filling so coolant can reach and fill the heater core.
Is it your headgasket?
My car would over heat at low RPM. I rev it up to past say 2500 and it cools down. Huh??? Turns out gases from combustion chamber were getting into the coolant system creating an airbubble at the top of the system. Spinning the water pump really fast forces water up into the head to cool it back down. (Just got the head back from the shop and miraculously it was not warped). Another symptom was no heat from the heater core at low RPM but had heat at high RPM.
Easy coolant draining:
Use a 6" by 1/2' ID hose from the drain to your pan to reduce the mess when draining the radiator.
Water pump:
If swapping the water pump get the one with a metal impeller.
haha