�65 Fan clutch question

[Oliver S.]

Ever since I have my ‘65 Corvette - now 12 years - I have been experiencing low temperature reading (as low as 150) when cruising steadily - otherwise it is between 180 and even above 200 when driving behind a very slow tractor up a hill. I checked the thermostat housing area with an IR gun to verify the accuracy of the gauge, which is ok. I replaced the thermostat - (180 degree Mr Gasket). The aftermarket fan clutch has more resistance when engine is hot - apparently ok. So I gave up ...
Today I decided to order a replacement fan clutch only to discover that the currently installed one is most probably a Four Seasons 36954 (I have the respective box with the part number on it from when I bought the car). Could a wrong fan clutch cause lower temperatures when cruising?

Oliver

[Russ S.]

[Bruce W.]

[Oliver S.]

[Larry M.]

[Joe L.]

Having a fan that pulls too much air will not affect the LOWER than factory design temperature as long as the thermostat is working and is correct heat range (180 F). It will only require additional horsepower to spin the fan more than needed.

Having a fan that does not pull enough air thru the radiator will affect the HIGHER than factory design temperature.............especially when idling in traffic or when car speeds are below 25-40 MPH. (40- 64 KM/HR )

Larry

Larry------


Absolutely correct.

[Chris D.]

[Oliver S.]

[Gene M.]

Ever since I have my ‘65 Corvette - now 12 years - I have been experiencing low temperature reading (as low as 150) when cruising steadily - otherwise it is between 180 and even above 200 when driving behind a very slow tractor up a hill. I checked the thermostat housing area with an IR gun to verify the accuracy of the gauge, which is ok. I replaced the thermostat - (180 degree Mr Gasket). The aftermarket fan clutch has more resistance when engine is hot - apparently ok. So I gave up ...
Today I decided to order a replacement fan clutch only to discover that the currently installed one is most probably a Four Seasons 36954 (I have the respective box with the part number on it from when I bought the car). Could a wrong fan clutch cause lower temperatures when cruising?

Oliver

From your description of the situation the thermostat you took out must have been a 160 degree. Which could for a period of time allow the engine to be cooler until it got warmer. In which case would be no different than the 180 unit you replaced it with.

The fan clutches could be different minimum engagements and/or more/less drag engaged at higher speeds.

[Oliver S.]

[Joe L.]

Gene,

maybe my initial posting was a bit misleading. After I hab bought the car in 2006 and had experienced the low temperature when cruising I installed a Mr. Gasket #4364 in 2008, which didn’t change anything, i.e. still a low temperature when cruising. As far as I understand Larry’s posting a tighter than normal fan clutch would not cause the observed behavior. Thus, my ordered fan clutch will be put in the shelf.

Oliver

Oliver------

If you installed a 180 degree thermostat and that thermostat is operating correctly, the engine's minimum operating temperature (after warm-up) should be 180 degrees. The only way it could be less than 180 degrees is if the coolant never achieved a temperature of 180 degrees. The chances of that are zero or about as close to zero as one could get.

[Oliver S.]

[Joe L.]

Oliver------

The fan clutch could have nothing to do with this situation so you don't need to be concerned about that.

I still can't figure out the low temp situation, though. As you describe it, it means that the engine cannot heat the coolant above 150 degrees under certain operating conditions. With a 180 degree thermostat installed that's the only way you could get the 150 degree readings you're getting. That's virtually an impossibility. The thermostat should control the MINIMUM operating temperature (after warm-up) at it's rated value. That's the whole purpose of a thermostat.

You could remove and test the thermostat to see if, perhaps, what you have is a 160 degree thermostat that's been packaged as a 180 or if it actually is a 180 but is not operating properly (i.e. fully opening much prior to 180 degrees.

[Harry S.]

[Oliver S.]