I suspect the thermostat is not opening in my 350. Sitting in traffic the temp starts to rise but comes back down if I get the car moving. The reason I suspect the thermostat is not opening is when the motor gets hot the top radiator hose seems to be pressurized when you squeeze it. I only have the factory gauge to go buy so I don't know the actual temp. Any comments? or suggestions? Thanks in advance,

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...DjD
69RS Ragtop

You can know for certain by pulling the thermostat out and placing it into a pot of water on the stove with a thermometer. As you bring up the heat, you can not only be sure its opening, but the temperature as well.

Might also check or replace the fan clutch. Sounds like you need more airflow at idle. tom

Thanks guys... I 'll put on the chief's hat and whip up some thermostat stew! As long as the car is moving the temp is fine so I see how air flow is suspect but the fan doesn't have a clutch its a 7 blade flex-fan. Would a larger spacer (putting the blade closer to the core) help air flow? It isn't very deep into the shrowd right now.

With the radiator, water pump and all being new I hope its just the thermostat not opening!

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...DjD
69RS Ragtop

A good rule of thumb for a sucker fan is to have at least 2/3 or more of the projected width into the shroud. For a venturi shroud, the rear of the fan blades should be even with the leading edge of the shroud. Try to keep at least 2" form the front face of the fan to the face of the core. This might be a dumb question, but you might want to make sure the fan is not mounted on backwards.