2002 Chevy Impala 3.4L. Replaced intake manifold gaskets, thermostat, water pump, cooling system flush, new radiator and temp sending unit and new radiator cap.
Question: I have bleed all the air out of the system and it's full of water. When I drive it to check it out it will do fine for a little bit and then the temp gauge starts rising and the heater stops blowing warm air.
I can rev the engine a little and the temperature starts dropping back to normal and the heater blows warm air again. The cooling fans are working fine. I have also noticed that when the temperature starts rising the air coming through the radiator is cool until I rev the engine a little and then it gets warm.
There are no coolant leaks and no water in the oil. I have checked online and there are alot of people with the same problem.I have ran out of money and have no idea what else it could be. I really need the car fixed. Can you PLEASE,PLEASE help me.
Answer: Yes, you have a blown headgasket. Just because there is no coolant in the oil or the other way around does not matter.
The reason the heat goes away, then you rev up the engine is because there is air in the system and you are forcing through the heater core to get heat from the vents. There is compression getting into the cooling system.
When compression leaks past a head gasket, it does not push coolant into the oil or oil into the coolant so you will never see it.
The rear cylinder head is the most common to fail. Almost always the #1 cylinder. That's the one on the passenger side. Remove the spark plug. You may find that it is contaminated.
You can also look at the back side of the head from under the passenger side and you may see orange residue of it leaking externally coming down the 3.4L intake manifold / head area. It would also be seen on the bottom of the head just under the exhaust manifold.
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