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Q: cooling issue

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replaced water pump gasket as it was leaking. hooked everything back up, tried to bleed cooling system, temp gauge went up higher than normal, replaced thermostat. same result. there is a knock in the upper hose that is loud and can be felt, even after the car is turned off. is this just trapped air? is the thermo not opening?

My car has 143000 miles.
My car has an automatic transmission.

A: Sometimes air can be trapped in the cooling...

Sometimes air can be trapped in the cooling system, effecting circulation. Generally, a normal fill and bleed procedure will work. With the radiator cap off, run the vehicle with the heater on so coolant circulates throughout the cooling system. Slowly add coolant and allow the system to "burp" several times. Once complete, reinstall the radiator cap and allow the vehicle to run for a short time. If it continues to run hot, then shut it off and allow it to cool a bit.

The next step is to try the bleeder screw. The 3.7 ltr V6 has a small bleeder screw where the upper radiator hose meets the engine. Remove the radiator cap again to relieve any pressure in the cooling system. Locate the small bleeder screw. TIP: if this screw has never been touched to your knowledge, spray it with some penetrating oil and allow it to work for 5-10 minutes before attempting to loosen it. It is a small screw and can easily be broken with too much force. Once loosened,(not removed), top off the cooling system until you see some coolant come out of the bleeder screw. Once you do, tighten it back up and replace the radiator cap. Try running the engine again, keeping an eye on the temperature.

If this does not resolve the running hot issue, have a certified technician inspect the cooling system to see if the problem lies elsewhere. Continued driving while running hot can damage the engine.

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