The car overheats but when I bleed the bleeder above the water pump it returned to normal. When the engine is cold and not running if you remove the radiator cap you will have a vacuum that sucks the coolant and Air into the system. No oil in the coolant no cloud of white smoke. If it runs at idle with the radiator cap off the thermostat will not open and the coolant reservoir overfills. It runs with no problem as long as I keep bleeding the bleeder above the water pump every 10 minutes or so. Pressure testing the coolant system to 15 PSI for 30 minutes. It held pressure. I tried to block tester with the liquid, but the Reservoir would overfill before I could complete the test. I have changed the thermostat and I change the water pump.
My car has 137000 miles.
My car has an automatic transmission.
The overheating issue may be caused by air bubbles trapped inside the cooling system. The fact that you're receiving that vacuum sound when you open the radiator cap indicates that you've got some air trapped in the system. This is common when radiator or water pump repairs are made and the priming process is not followed precisely as recommended by Chevrolet. If you need help trying to diagnose this overheating issue, one of our professional mechanics will be happy to help you.
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