Check out
Engine Watchdog (
ENGINE WATCHDOG Audible Engine Overheating Alarm, Gauge & Sensor)... they have
single and double
sensor models. Clamp onto a bolt or hose clamp onto
exhaust where it goes from metal to rubber. As others have pointed out, just set it to
alarm at above "normal"... doesn't really matter what normal is.
I ran the
engine up to normal temps in normal conditions and set my three alarms (bolted to engine block, wrapped on
exhaust, bolted to transmission) a little higher than they were reading. I've had to adjust up a bit here and there (after first confirming it was just adjusting my reading, I wasn't actually experiencing an issue) and they've been silent ever since, but I know they're there!
-- Bass