MF 362 thermostart problem

peachfarmer · Oct 22, 2014

lets talk voltage! 12.75 at the new battery, 12.6 at the starter 12.45 at the switch from starter turn the key to start starter voltage drops to 11.6 disconnect the thermostart lead wire from the switch and voltage returns to 12.4 at starter, at the end of the thermostart hook up 12.4 unplugged. jumping across to thermo with 12 volt light I get nothing the thermo is reading good resistance with ohms. What do you guys think? thanks for any advice

Winmac · Oct 22, 2014

Seem like excessive voltage loss considering no load, I wouldn't expect to see any voltage drop between the bat and ignition. the thermostart draws a fair bit of power so I'd expect to see a drop but I don't have any numbers.

What is the issue, will it not start? I'd probably look at the cables for corrosion, or poor connections.

peachfarmer · Oct 22, 2014

This has been a ongoing problem with this machine. I replaced the starter now it has gone out again not the starter but the low voltage side of the solenoid. However this is not the root cause. What I trying to clarify is with the switch on shouldn't the thermostart drop out and allow full load to be delivered to start the machine. Ive been bypassed the switch jumping straight from battery lead to solenoid. this is what I think has burnt the low voltage side of the solenoid coil that turns the starter. I don't understand the function of the thermostart other than heating something. Not like a glow plug though PLEASE clarify and thanks

Winmac · Oct 22, 2014

When the thermostart is powered it heats up and ignites diesel fuel, the flame warms the intake air and is drawn into the engine when cranked.
I do not know how your tractor activates the ts but it shouldn't be powered while the key is on. Typically there is a heat position on the ignition sometimes it's labeled or not, it may be a matter of holding the key between on and start.