I went to add a little coolant to a cold engine. When I went to remove the cap it released pressure and the coolant level rose like it was hot. Is this normal? I have had a problem with the coolant leaking out of the overflow tube.

Thanks,

Chris P.

Unless there is a problem with the radiator cap you shouldn't have much pressure build-up. Possibly there is blow-by from the head gasket getting into the cooling system! Have it checked out soon!

The cap has two functions. It holds pressure in to raise the boiling point of the coolant but it also has a check valve built into it to allow for contraction when cooling. If this check valve fails you may hear a sucking sound when you remove the cap. That sound is actually vacuum not pressure. I would replace the cap before going any further.

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