radiator fan switch

[Scooter33]

The reason you put a fan switch in the bottom of the radiator rather than in the block is the fan is only used to cool the radiator water not the water in the block

The thermostat is the item that controls block temperature.

when the switch is in the radiator, which is what the fan is cooling, and it gets to the desired temp the fan will switch off


When you install it in the block the thermostat and the fan switch will be fighting each other for control.

The radiator water gets colder than necessary then goes into the block when the thermostat opens and you get fluctuations in block temperature which may cause damage to the block


Scooter33

[model a vette]

I just helped a friend change over to the minivan sender from an adjustable sender in the bottom of the radiator. We are using a tapped hole in the top of the water pump for the sender. I think that will give a similar reading to the minivan's stock placement.
The fans he is using are aux fans as he has a mechanical fan on the pump. We won't know how it works until the Spring as the changeover was part of a larger engine project.

[Crosley.In.AZ]

bottom of the engine block would not be a proper place with th e gunk build up  as mentioned.

I have a temp  probe in the radiator fins  near hot water entrance. The adjustable controller is set so the fan comes on if the car sits at a traffic  light.  Not sure how I got the adjustment that close , but it works well on the 1961  Dodge  Lancer car  so far.  Built in Bosch relay  plugged into this controller..

[Jokester]

Thanks for all the input.  Rumrumm wins the prize.  I looked at the thermostat spacer that Summit and others offer.  I decided I could make one so I did.  The fan switch is now in the intake below the thermostat where I wanted it.

Thanks all.

.bjb

[rumrumm]

Thanks! It worked great for me.