What does it do?

bjdw, Jun 24, 12:20pm
Or what is it not doing would be more to the point.

On my Toyota 4Y there is a sender or switch on the top of the head at the front.It has a single blade terminal.There is no wire attached to it.The temp gauge works, so it's not for that.The fan is mechanical so it's not a fan switch.It's carburetted so it's not a temp sensor for EFI.

phillip.weston, Jun 24, 12:25pm
perhaps oil pressure switch. Are you able to take a photo of it!

doug207, Jun 24, 1:25pm
Pull it out and see, my guess is a temp sender for an auto choke unit.

jsbike, Jun 24, 1:27pm
it prob had a wire going to it many moons ago

ceebee2, Jun 24, 1:39pm
Its the thermatic fan switch.

ceebee2, Jun 24, 1:40pm
Probably an import manifold that had the electric fan

bjdw, Jun 24, 1:51pm
It's got a manual choke, but maybe that is aftermarket.

40wav, Jun 24, 4:59pm
File it off, that'll learn it!

bae13, Jul 22, 3:56am
some of the imports had a flap thatdirected air when the engine was cold to be sucked from around the exhaust, as the engine warmedthe switch in coolant operated a vacuum valve which then moved the flap which then switched to normal air, some of the air cleaners had a metallic pipe that hung down to a steel pipe on the manifold