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Q: Water coming out of overflow tank

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My car started over heating bad so I changed the radiator and cap, water pump, thermostat and lower radiator hose. It was still overheating so I did a head gasket job on both heads. I got the full gasket kit and replaced all the gaskets. I wired my fans so they are always running when the key is turned on. But now when I drive and put the car in park and turn it off water starts flowing out of the overflow reservoir. What could be the problem?

My car has 18000 miles.
My car has an automatic transmission.

The coolant in the engine has the job of removing heat from the engine and releasing the heat by way of the radiator. The coolant is circulated by the coolant pump. If there is a pressure created internally other than the coolant system creates, it can prevent this flow. If coolant is coming out of the overflow it is overheating. Coolant system failure can be a slow process until the signs are hard to ignore. Running the coolant fans are just masking the problem.

Antifreeze has a time limit before it needs replacing, five years is the maximum time allow. If the vehicle has been overheated to a damaging point it can crack the engine’s cylinder heads causing a pressure to enter the coolant system. This will stop or slow the flow rate of the coolant pump which will cause a overheating condition. There are tests that can be preformed to confirm this. I’d suggest getting some assistance from a certified technician, such as one from YourMechanic, to diagnose your overheating issue and make the necessary repairs.

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