PatrickIreland
ArboristSite Guru
I don't think it would have to be expensive at all. A heat sensor, wire, and an LED basically. Still, since we ain't got it, there must be some impossible hurdle...maybe.
Shouldn't be too hard - a high-temp thermistor on the cylinder fins, watch battery and one of those ready-made flashing LEDs?
The onlyproblem would be calibrating it for each saw - you might have to burn out another piston to determine what is "too hot" for your saw!