kevdog442

This was one of the head bolts on my 68 455 Toro motor. What's its purpose?

MDchanic

Secondary head temperature sensor, used on '68-'70 Toros, located at spot just above trans. dipstick, light green wire with white stripe, makes a yellow light flash "STOP ENGINE."

Works completely independently of the red "HOT" light attached to the sensor in the water jacket on the intake manifold.

- Eric

kevdog442

Ok thanks, never seen this before. Toronado only?

MDchanic

I think some or all of the diesels may have had it, too, a decade later.

- Eric

rustyroger

I never came across a diesel with one of those, but then I never saw a diesel that hadn't already been rebuilt at least once.
Seems like a Citroen way of doing something imo.

It looks to me like the bottom threads are stripped or damaged?.

Roger.

Koda

And he doesn't even get paid for giving that info.

So, I'm assuming this bolts into a dead hole on the block and it just takes temp from the block itself, or does it punch through to its own water jacket spot?

MDchanic

It's just one of the lower-row head bolts.
As far as I know, the idea was to read the head or block temperature as close to the combustion chamber as possible, probably because these cars did run hot sometimes, did not have a temperature gauge, and some drivers grew to ignore the HOT light.

- Eric

cherokeepeople

the diesels used those bolts for sensors to tell the glowplug controller if it needed to work or not and for how long.but the heads were alot taller.

rustyroger

My '79 88 Royale had gauges from the factory. But mostly they didn't.

Roger.

toymobile

455 Buick had heat sensor that screwed into back of head to turn the AC OFF if engine temp reached dangerous level. GM tried to protect US from ourselves. LOL