Been having overheating issues with my 99 cavalier 2200sfi engine.. Have gone thru a new thermostat/ water pump/ fan relay / radiator /antifreeze cap/ head gasket... Then tried a coolant flush .. The car was still overheating... It got too hot on the highway n I blew the head gasket... Then someone told me it was a engine problem so I got a junk yard motor that was in a lot better shape then mine with way less mileage put that in and the car ran good for two days then todayit started getting really hot again and the heat started blowing cold.... Please help any ideas or suggestions would be greatly appreciated

Your cooling system is pretty simple when you really look at it. You put coolant in the overflow tank. It fills the radiator, but not completely. Here's why. Look at the hose from the coolant tank to the radiator. It enters the radiator about half way down. However, on that engine, after the coolant leaves the radiator via the lower hose, it enters the coolant pump, then into the block. It also has a hose that goes to the heater core. From the block, it goes through the head and then to the thermostat. Once through the thermostat, it meets back up with the coolant it left for the heater core and returns back to the radiator via the upper hose. Now, there are a couple small pipes that send coolant back to the overflow near the cap. These are useless in my opinion. Anyhow, what I most commonly see when I get one of these chronic overheating issues, is that the person topping off the coolant did not let the engine come up to temperature and the thermostat open before putting the cap back on the overflow bottle. It is a poor design by GM, much like a chain driven water pump on the LD9. The air pocket created when filling uo the cooling system needs to be purged in order to prevent an overheating issue. If you don't have to bleeders, then you need to exercize patients and inginuity when filling the system. I have removed the upper hose at the radiator. With a flexible funnel, I pour the coolant in there until it starts to dribble out. Be patient though, because those two useless pipes that dump into the coolant jug will bleed air back out the cap, slowly. After some well exercized patients, you will not be able to pour a drop more into the radiator. Put the hose back on and finish topping off the coolant at the jug. Start the car and keep an eye on the fluid level in the jug. When it drops without flooding out, slowly pour coolant into the jug until the jug is at the full hot mark. If purging the air completely from the system doesn't fix your overheating problem, then I would say you have a problem with one of the other components I have listed in the cooling system. I would systematically start working my way around those components till I figure out which one is causing my problem. But to me is sounds like trapped air, and once that is gone, so should your overheating issue.



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