I recently bought a thermal switch for a single fan setup. It's supposed to switch the fan on at 200 degrees, off at 185 degrees for use with a 195 degree thermostat.

Instructions say to mount the thermal switch in either the cylinder head or intake manifold.

-My original stock switch was smaller and screwed into the side of the block where one of the coolant drain plugs are. I can't do that with this new one because it's bigger in diameter. Can't mount it in the head because my temperature gage sensor is screwed in there, so I pretty much have no choice but to mount it into the intake manifold near the T-stat.

Question is, how does mounting a sensor in the intake manifold going to control the temperature accurately?? It seems to me....(maybe I'm over thinking this)... -that when my T-stat opens, the water temp will be accurate to the sensor...because there will be a flow into the intake - right?

-but after the fan turns on at 200 degrees and drops the temp below 195 degrees, the T-stat will shut again right?? So will my fan be able to continue to cool it down to 185 degrees with the T-stat shut, or will my fan continue to run and never shut off???

Seems to me the location in either the head or block would be more accurate, or am I missing something here??

 

The factory sensor location should be in the pass side head right between cylinders 6+8, you have to kinda feel for it, its tucked up under the exhaust.

Sara Lou

 

Best is a fan switch that fits like the stock one in the block.

185°off with 195° thermostat = fan on all the time once it turns on. For that switch you need 160-170° thermostat.

210on/200°off fan switch will work fine with 180°thermostate.

Tese here fit in the stock hole.

http://www.rodneydickman.com/n20.html

 

You're absolutely right! It's been so long since I had a stock fan control on the car I forgot where the sensor actually is SUPPOSED to be. I found a plug in my pass. side Dart head, (between cyl. 6 and 8) so I removed it and put my sensor there. Thx!

 

You can get adapters to fit those at just about any hardware store...just bring in your old switch and the new switch to figure out which size you need. I had to do that on mine because the new heads I put on had a different diameter plug hole than my factory ones did.