[dosdaytona]

Was thinking of JB welding a new thermo switch in

Welding the head can be tricky, casting might crack if it cools rapidly in any thin spots-if you try JB weld or putty, the switch needs to find a ground or light will stay on. Could relocate it ,close up the hole with filler or weld -I used a bronze pipe nipple, tap, install sender ,Soldered a ground wire to the nipple, cut the water exit rubber hose about 4 inches down, 2 hose clamps done deal -

 

[dosdaytona]

How to I ground the switch? If the switch still has some original threads in the casing is it grounded?

On the head casting if a filler is used like JB weld it all depends-the filler could isolate the sender completely-cant really just keep tightening into the filler like aluminum….temp light on key on no ground.