I just replaced the water pump in my 2005 Ford Escape V6.

I discovered that each time I fill the coolant reservoir with coolant and drive the car, by my next stop the coolant reservoir will be completely empty. I can't see water leaking or dripping from anywhere in the car. This has happened 3 times now.

What could be the problem?

  • Have you tested the radiator cap(s)? – Zaid Dec 8 '15 at 7:21
  • Well if it's not dripping then it's either evaporating or burning. And I doubt you can burn a whole reservoir in one drive. – I have no idea what I'm doing Dec 8 '15 at 12:21

A bad radiator cap can explain this.

If the cap opens at a lower pressure than what the cooling system is rated at then coolant will be released through the overflow tube once that pressure is achieved, which it will under normal operation.

I would test/replace the radiator cap and see if that remedies the symptoms.


The first comment is that there MAY be a special fill procedure for your car. If you are not observing the fill procedure, you may not be putting enough coolant in, and OF COURSE the car will drain the tank, to fill the cooling loop, once the thermostat opens.

The second comment is that this sounds as though the car is burning coolant. Think "blown head gasket". Start by taking a look at the engine oil. Your shop may be able to tell something with an exhaust analyzer.

I had a problem with a 1990 Chevy Lumina 4-door sedan gradually draining the coolant tank. Newspapers under the car revealed a leak SOMEWHERE, but I couldn't see where. I finally got lucky, and saw a leaking gasket at the bypass union, that turned out to be a worn union. (That repair was what triggered my search for a replacement vehicle: getting a replacement part was a lot harder than it should have been.)

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