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2000 chevy cavalier overheating


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03-28-04, 01:13 PM   #1  
ddj690
2000 chevy cavalier overheating

Help...about two weeks aga my 2000 cavalier started leaking from the water pump. The leak was very small but I replaced the pump anyway. I also took the liberty of replacing the thermostat. Now the car is doing even worse. I refilled the coolant and I bled the excess air from the only valve I could find. In other words once the coolant started to come from the nipple I closed it. Now the car will run at idle for 20 minutes or so at good temp (195) and then it will start to over heat...the cooland just gushes from the overflow tank. It gushes out even worse when I put it in drive and try to go around the block. The fan comes on at about 200-205 degrees but the needle continues to go to the red. What am I doing wrong????

 
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03-28-04, 02:09 PM   #2  
Could you have put your thermostat in backwards?

 
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03-28-04, 02:13 PM   #3  
Sounds like you're not getting coolant flowing completely through the system.

Some possibilities and things to check:

1. Plugged radiator - did you flush it?
2. Air in system. Double check this even if you believe you got it all out the first time.
3. Check upper AND lower hose temps - if you can rent/borrow a temp gun it helps a lot.
4. Check radiator temp from input to output. Should be about 100 degree difference if the radiator is working properly.
5. Check flow through the radiator. Checking the temp difference should tell you this, by looking (CAREFULLY) in the filler neck with engine running you should see flow.
6. LEAKS - pressure test the system if you have access to a tester.

Matt

 
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03-28-04, 03:59 PM   #4  
None of those things got worse from changing the water pump and T-stat, especially to the point he's describing. If the top hose isn't getting real hot, check the T-stat. It's likely facing the wrong way. The spring goes toward the engine..

 
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03-29-04, 09:00 AM   #5  
ddj690
Me again

OK. I double checked the thermostat and it is in properly. I can also see water flow through the filler neck. What I did discover was the gasket on the filler bottle slipped loose so I placed it back in the groove so that the cap would seal tightly. I noticed that the cap is rated at 15 psi so I imagine at 15 psi it vents the system if need be. Now that the cap is sealing properly I have noticed that the radiator hoses are firm when the car is running (they were soft before so I belive the system was not getting pressurized>) However, I started the car and it idled for 30 minutes without exceeding 195 degrees yet when I put the car into gear and drove around the block it started to overheat again. The temperature immediately went back to 195 when I parked the vehicle and kept it running. HELP. P.S. I get great heat flow through the inside heater.

 
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03-29-04, 03:33 PM   #6  
Did you add any type of sealer trying to fix your earlier leak? It's acting like you have a total blockage somewhere. Using sealer would have plugged the radiator real good. It's a silly question but you didn't wrap the serpentine bellt the wrong way did you. I believe the water pump has a smooth pulley so that means it is driven by the backside of the belt. Dumb question but I'm trying to cover all the bases. Did you ever get it really hot before when you had the leak?
That bad cap would have made you eventually lose enough coolant to overheat but it isn't causing what you describe.

 
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