Won't start when hot

[rScotty]

It is pretty common for starters and solenoids not to work right when they get hot. The internal resistance goes way up when the windings get hot, and sometimes it just can't draw enough power - especially if it is marginal to start with some rust, worn brushes, and bushings.

I'd take it to an auto electric rebuilder and have them go through and do a basic service on the starter and solenoid. Usually that's about $150 bill if they have to turn the commutator and put in bearings.
By the way, having that all done to an old JD starter is far better than buying a no-name rebuilt starter.

Then check out your battery and cables and particularly the cable to the frame ground.

All of this will probably fix it. But if it doesn't, consider it as maintenance that has to be done every 20 years or so anyway.
rScotty

 

[Jerry/MT]

Hello, We have a 1979 JD 2040. Starts fine when cold. We do plug it in when temp is below 30f, to make things easier. The starter does have some bad spots, but if you get past them (hear the click) it will go. Problem is once the engine gets hot, and you have to turn it off for something, it will not restart. No clicks, nothing. Give it some time to cool down, and it will start again. It has new batteries, new positive and neg wires. Suspecting the starter or solenoid, but not sure what to look for. Where to start? This happens more in hot weather.

The starter does have some bad spots, but if you get past them (hear the click) it will go.


I guess you can continue to "...get past them (hear the click) it will go. ", but it sounds like a worn starter/solenoid.

If it were mine I'd rebuild it or get a rebuilt or a new one on the internet. If you get a new one , see if there is a gear reduction starter for your tractor.

What is the purpose of a thermistor in the starter circuit?

 

[Harry in Ky]

Good question on the thermister. I don't know the purpose either, but I don't think it's in the starter circuit. I was under the impression it had to do with something fuel related. Shutoff solenoid, or that sort of thing. Maybe some who knows will straighten us out on that.

As for the starter itself. I too have dealt with bad starters on three and four cylinder tractors of that vintage, both with and without loaders. The two bolts involved can indeed be no picnic. To those who blindly suggest to repair, rebuild, replace, or whatever. While that may be sound advice long term, it's also easy to say when someone ELSE is taking it off and putting it back. If I'm the one doing it, I want to know if that's my problem first.