What Is A Yanmar Thermo-Start (Glow Plug)

A Thermo-Start plug is Yanmar's solution to the normal glow plug. Instead of having a traditional glow plug to heat up each cylinder, Yanmar uses a bigger ThermoStart plug in the intake manifold to heat the incoming air. This Thermo-Start plug burns a tiny amount of diesel fuel from the header tank (the small plastic bottle located right above the ThermoStart). This burning fuel creates a dense smoke and sometimes small flame that gets sucked into the engine to help the engine start easier.  

So how does it work? When you engage the Thermo-Start you apply power to a small heating coil. The coil heats up a tiny valve that expands when it gets hot. The valve opens and allows diesel to drip onto the hot coil. When the fuel smolders or burns it greatly improves the efficiency of the glow plug. 

To engage the Thermo-Start you rotate the key counter-clockwise to the momentary 'TS' position for 10-15 seconds then start the tractor normally. The ThermoStart is also energized while the key in in the 'start' position.