High pressure temp switch

[chicken bones]

My truck has not been going to high idie , at least not right away. I bought a new high pressure temp switch , i see it threads in just behind thermostat , my question is do I need to drain off some coolant or is this switch on the oil side of the block ? thanks for your help.

 

[chris142]

Leave the radiator cap on but with the engine cool. Change the switch quickly and you may lose a few ounces of coolant.

 

[chicken bones]

Thanks, few onces sounds OK .