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Q: Coolant keeps magically disappering...

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No leaks are present underneath the car. I took it to NTB and they did a pressure test, no sign of a leak. They replaced my upper radiator hose and did a coolant flush. I thought all was fixed on my car until about 2 weeks later, I was driving and my cars' temperature went all the way to hot and my air conditioning instantly stopped. I pulled over and waited for the engine to cool off and looked at coolant level and again, all of my coolant was gone. Where is the coolant going if there is no leaks?? What may be the issue with it magically disappearing??

My car has 95000 miles.
My car has an automatic transmission.

A: There is a leak, it just hasn’t been found ...

There is a leak, it just hasn’t been found yet. I would begin by having a close look at the radiator cap - a visual inspection and a pressure test. The cap is so inexpensive I would just replace it with a new one.

Pull the dipstick and inspect the oil. Remove and look at the oil fill cap and inside the valve cover. If you see any foaminess or latte-looking stuff, you are seeing water (coolant) in the oil.

Your Aveo should have a pressure tester put on the cooling system cold, and then start it and let it warm up while observing any pressure changes and looking for leaks. Let it run for awhile with pressure tester on it.

Someone will need to go under the car while its running, warmed up, with pressure still on the system, and inspect closely for leaks. If no external leaks are found, then coolant is leaking internally into the engine. This can happen through a leaking head gasket or cracked head. A head gasket test could also be performed to test for the presence of combustion gasses in the cooling system.

If you want to have this checked, a certified mechanic from YourMechanic can come to your home or office to diagnose your coolant leaking problem and help you move forward with repairs.

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