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Q: Fluctuating coolant readings

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I have been getting a fluctuating reading on my coolant recently. My dashboard sensors are going from normal to 260 and back down. It goes up and down in readings the entire time I am driving. I changed the coolant, temperature sensors and thermometer. I didn't use a torque wrench to do this with. The problem still persists. Do you know what is going on? My engine seems to be a normal temperature.

A: Hello. Your fluctuating coolant temperature...

Hello. Your fluctuating coolant temperature may be caused by a cracked cylinder head or leaking head gasket. It sounds like you have replaced everything else that could be causing this issue. If the head is cracked or the head gasket is leaking, this can cause combustion chamber gases to get into the cooling system. When this happens, it forms an air pocket. When an air pocket reaches the coolant temperature sensor, it will read hot because the air from the combustion chamber is very hot. I recommend having a local expert inspect your cooling system to determine if there are any emerging issues such as overheating or leaks that need to be addressed.

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