My daughter's '96 Cavalier is overheating. At first I thought it may be the thermostat (it still may be), if I drive the car for about a mile the gauge climbs up to H. The overflow tank is full and antifreeze comes out the top. I have heat as long as I rev up the engine. At a loss, any help is appreciated.
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you got some major issues buddie.. i had the same problems .. either you have a blwn gasket or a cracked head..
test to see if the thermostat comes on .. while the car is on.. listen for the clicking. if not then its stuck or frozen. replace it and see how it goes. let me know then
test to see if the thermostat comes on .. while the car is on.. listen for the clicking
In all my years as a mechanic, no one has ever suggested this one. Most thermostats will not open fas enough to make a "click."
There are a few possibilities. First, if you have a fill port directly to the radiator, make sure you have enough coolant in the system. The reservoir tube can become restricted causing the bottle to stay full while the system becomes empty. While you're in there look inside (while the engine is cold) and check for a buildup which looks something like wet sawdust mixed with mud. If you find a substantial build up you are likely to need a good cooling system flush.
If the thermostat is the only component not operating properly you should still have plenty of heat. But there could be multiple problems. A sticking thermostat can often be found by simply checking the coolant hoses when the engine temperature gauge shows the engine is warm. Warning: if you use your hand to check these parts, you run the risk of being burned. With the engine at temp, touch the engine to get a sense of it's temperature, then touch the upper and lower rad hoses. Upper hose should be as hot as the engine, lower hose should be cool or cold. If you locate and touch the two heater hoses, one should be as hot as the engine, the second should feel very warm.
It's possible the head gasket is failing and allowing combustions gases into the cooling system. This could force coolant out of the heater core and out of the top of the cylinder head. If this is happening, you might see signs of it by opening up the coolant reservoir while the car is cool, starting the engine, then watching for bubbles in the overflow. You might see a few while the engine warms up, but after the car is warm there should be none.
Mechanics use tools which draw air from the reservoir through a chemical which changes color in the presence of CO2 to detect exhaust gas in the coolant. We also use infra-red thermostats to measure hose, radiator, and engine temperature. These tools are not the only way, but they can help save a bunch of time in the diagnosis stage.
try it before bashing .. it will click. ill try to get a vid.
A thermostat doesnt click
Take one, boil some water to about 200 degrees or so and drop it in
If will not click
I wasn't bashing. I've never heard anyone, even the old timers, recommend listening for a "click." There are much better, tried n true ways to check for T-stat operation.