I have a 2005 Ford Escape. It overheats once in a while up to the point that you can physically see coolant in the reservoir tank boiling.
My main concern is that the temperature gauge on the car dashboard does not rise beyond the middle.
What could be causing this issue?
Given that you're regularly losing coolant it would seem that your radiator cap isn't allowing the coolant system to build up the pressure that it is designed for.
At lower pressure, coolant will start to boil at a lower temperature, which would explain why your coolant is boiling but the temperature gauge reads normal.
I would test/replace the radiator cap and see if that remedies the symptoms. If not, it possible that the engine coolant temperature sensor is bad.
You can test your coolant temperature switch using hot water and a multi-meter. You'll have to look up the specifications of your coolant temp switch/ sensor. You'll just have to dip it in some water and wire up some electrical to test it. If you don't feel comfortable doing that you can just replace it to be extra sure. If you have boiling water in your overflow reservoir it could be quite a few things. It could be anything as simple as a bad water pump or possibly a blown head gasket leaking combustion gasses into your coolant jackets. If you goto a parts store you can rent a testing kit that will allow you to pressure down the system and find the source of your leak. It could be many places so you have to be patient and meticulous about finding it. Try to find the source of the issue before you spend lots of money on replacing parts. I know replacing parts is easier than finding the issue, but if you spend the extra time going over the system you'll save a buck. I would also do what @Zaid said. It can't hurt. I hope this was helpful! Good Luck
