Big GMC truck
Registered Member
I'm replacing a vacuum switch that is located on my water outlet. Will coolant come out when I take out the switch? Do I have to drain the coolant? Do I have to put anything on the threads of the switch? Thanks
CK5
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vacuum switch install
- Thread starter Big GMC truck
- Start date
Coolant will come out. I first coat the threads of the new sensor with Permatex Form-a-gasket and then just thread it in quickly after removing the old one. If you do it right, you'll only lose a few ounces of coolant. 
If you are talking about the thermal vacuum switch on the top of the thermostat housing, should only lose a couple of drops of coolant. I used teflon tape on my threads-not sure what GM recommends but didn't seem to leak afterwards.
