I have a 1998 Chevy cavalier with 130K miles on it. We replaced the thermostat because it went bad an overheated on us. We also replaced the radiator, fan relay and water pump to avoid future "surprises". It's still overheating (even in idle)and the fan is coming on like it should. From what I'm reading, we should bleed the cooling system. Ok, so how do we bleed the cooling system?
I know the thermostat is in correctly. I know that the fan is running like it should. I know that the hoses are not clogged and are all connected. I know that there is not a leak from the new radiator. Boyfriend is a mechnic, on large trucks and tanks and things like that, this is a different animal. He did a compression test on it and the head gasket has not been compromised. We just got this car 2 weeks ago and don't know it yet.
February, 25, 2011 AT 10:50 PM
Bleed the cooling system by removing the top cap, that lets the air out, and you can add coolant to the radiator, and bleed it out in that fashion. If you need to bleed your cooling system as a unit, that's an entirely different procedure. That outline is going to be given to your owner's manual, and that depends on where the highest point in the cooling system is, as to what the bleeding procedure is, but for a radiator, as long as the cap is the highest point of the radiator, that's how you'll bleed a radiator. If there's a higher point on there, that can trap air in it, you're going to have to put a bleed valve on there, to let the air out, or the system isn't going to bleed correctly, so if you have to bleed a cooling system, what you're going to need to find, is that bleed valve, and that just depends on whether there's a point in the cooling system, that exceeds the height in the cap of the radiator. Wherever the highest point in the cooling system is, that's where it's going to trap the air, and that's where a required bleed point is going to be, but for most vehicles, a radiator, and a radiator cap, is the highest point in the cooling system, and so the radiators can be bled, just simply by removing that cap, and allowing the system to fill up, until all the air is gone. You need to remember also, that there's a thermostat in the system, and when that's sealed, or in the cold or closed position, it can trap air into the bottom side of the engine, so you want to make sure, anytime you're trying to bleed the system, after you've bled it, you've run the engine for at least fifteen, twenty minutes, make sure it's thoroughly warmed up, and the cooling system has cycled several times, and then recheck it after it's cooled, and re-top as necessary, to remove any additional air, that might have been trapped in the engine, so that's how you bleed a radiator, and/or cooling system."