Overheating All hoses stay cool except for two top radiator hose?

MARTYRT1957

MEMBER
1997 FORD CONTOUR
4 CYL
FWD
AUTOMATIC
150,000 MILES

All hoses stay cool except for two top radiator hose and the small hose from thermostat housing to the overflow tank. Heater air stays cool. I took out the radiator and the heater core and they were not clogged. As long as the car is idling in the drive way, the temperature gauge stays close to cool, even though the two hoses get very hot. As soon as I start driving, the temp gauge shoots up to the red like a rocket! The radiator was replaced a year ago and the water pump was replaced seven years ago. The water pump is not leaking or making noise. This car has always run warm. We had an overheating problem in 2003 and it was in the shop at a ford dealer for a full day and they were unable to diagnose it. They flushed the cooling system and it didn't seem to make a big difference.

1 Reply

SQM

MECHANIC
6,383 POSTS

Hello,

It sounds like a stuck closed thermostat.
When the thermostat fails at stuck closed position it will prevent the coolant from flowing. Which will create a significant temperature difference between the upper and lower radiator hose.
It is possible that the engine actually overheats as you are idling and as soon as you drive, it has little better circulation and shows the actuator coolant temperature.

Here are a couple of helpful articles:

https://www.2carpros.com/articles/how-an-engine-thermostat-works
https://www.2carpros.com/articles/replace-thermostat

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.

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