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Question:

water pump went bad. changed it. car is still overheating. why?

my water pump went bad on my 1997 chevy cavalier, causing it to leak all the coolant it had in the system. i put water in it til i could get new water pump. changed out water pump. attempted getting air out of system. put more concentrated coolant in system than i did water. bad guessing on my part. ran car around block 5 times. it was fine. this morning on the way to work, it started overheating again. my thoughts : more air in system that's not coming out? thermostat REALLY went bad at same time as water pump???? overheating all because of a little too much coolant??? for some crazy reason, my system needs to be suddenly flushed? Your thoughts? one last thing, the car has always ran perfectly normal temp til water pump went bad.

Answer:

When was the last time the system been drained flushed and *cleaned? A 14 year old radiator and heater core will be loaded with corrosion and rust. Prestone Super Radiator Cleaner can be used on mildly dirty cooling systems. *Follow the instructions on the back side of the Prestone Super Radiator Cleaner. The instructions are totally different than the quick, worthless rinse cleaners. GM makes a one part powered acid cleaner that works better on really dirty cooling systems. When in doubt change the AC-Delco thermostat with another one from a Chevrolet dealer. Flushing is easy when you splice-in a Prestone or Peak flushing T in the heater hose *return hose from the heater-core. Any trusted private mechanic or Chevrolet dealer can do a *cooling system pressure test to see if you have any external or internal coolant leaks. Never exceed a 50/50 mixture of DexCool antifreeze and distilled water. If someone has been mixing brand X antifreeze with the factory installed DexCool in your cooling system the coolant will turn to mud and plug-up the cooling tubes in the radiator core and mat the cooling passages in the engine. The secret of perfect heat-transfer in a cooling system is clean cooling passages, a new AC-Delco thermostat and radiator pressure cap. Remove and clean the plastic coolant recovery bottle with Wisk, hot water and a round household scrub brush. If you exceed a 50/50 water and DexCool mixture, it will not adsorb heat from the engine as efficiently or get rid of the heat in the radiator as well as a perfect 50/50 mixture. Always buy 100% DexCool Antifreeze and fill 1/2 the total capacity of an empty clean cooling system first with 100% DexCool then fill the remaining space with distilled water.
Check your radiator,check your radiator fan to see if it works! Sometimes they go bad or their sensor won't work anymore and the car is overheating the sensor doesn't pick that up and the fan won't start! That's make the car overheating!
sounds like a air block in the cooling system. leave the radiator cap off and start it. the air will push the antifreeze out but once the air is out it will start to circulate. you will have to add more antifreeze before putting the cap back on. don,t forget to add some to the reservoir.
Sounds like a typical air lock, you need to bleed the system, should hopefully be a bleed screw often running off heater pipe at the back of engine! Check to see if top and bottom pipe are hot when running, or heater not blowing warm usually a good indicator of air in system! Just found this! To bleed the cooling system on a 1997 Chevy Cavalier, there is a small brass bleeder valve located on the heater pipe that runs along the front of the motor (metal pipe). Open that valve a couple turns and pour in the antifreeze in the reservoir tank until antifreeze starts dripping from the bleeder hole. Tighten the valve, but be careful not to tight too tight, they are soft brass and break easy. Finish filling the reservoir to the Full Cold mark. After driving the car at least one time and letting it cool down, check the antifreeze level on the reservoir and fill as needed.
Maybe the hoses aren't connected properly and water is leaking out? Have you had the bonnet up to look at the engine while it's running to check for leaks? If you can't sort it out, take it to a garage

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