John Deere M Starter

[Dave Cole]

The starter was not turning the tractor over at all. I removed the starter, cleaned the area in and around the brushes and made sure it was lubricated. I bench tested it and it turns over nice seemed to have pretty good torque. I reinstalled it and it just barely turns the tractor over. Any ideas?

 

[CPeter]

[u:0969d1c096][b:0969d1c096]First of all you DO NOT need to convert it to 12V!!!!!
[/b:0969d1c096][/u:0969d1c096]
Check to be sure the bushings are not worn. this is often the cause of you problem. It will spend great with no load, but when the start engages, the armature is offset in the housing and drags on the field windings.

The other ting to check is the condition of the battery cables and the connections. The original ground connection is to the dash pedestal and that has to make a connection to the center frame housing and that to the starter. You get the picture, a lot of rusty connections. Try running a ground cable directly from the battery to the starter or at least to the set screw that holds the starter in place. Also, sometimes the switch itself is bad. check the contacts on the switch and the starter.

Did you replace the brushes? Check the springs the hold the brushes against the commutator. I have seen those fail, not very often,

I have a 420 with the same starter and it starts fine a very cold temps here in New Hampshire in the winter. If it turns over slowly, something is wrong. Check the things I mentioned.

CPeter

 

[Donald Lehman]

Another possibility to consider. if I start and stop my 420 frequently the generator will not charge the battery fully and within a short time the battery is way low. Worn bushings is more likely the problem, but I'd check the battery anyway.

 

[Dave Cole]

Thanks for the advice. I had taken the switch off the starter and was connecting the NEG right to the starter.

I will have the battery checked this week. I will also clean up the POS gnd connection.

The starter has never been touched (brushes are the original) I will get a set and install them and get a new switch (it has issues).

Thanks again for the advice

 

[CPeter]

Also, check the bushings in the end caps and look at the armature to see if it shows any sign of dragging on the field.

CPeter

 

[Tim14167]

Agreed do not change to 12 volts, there is no need to do this. the 6 volt system worked fine for over 60 years, why change now.

Check the timing of the distributor. I have seen this on my 1950 John Deere M where the distributor was timed incorrectly. The starter would turn the engine over "OK" when it was on an exhust stroke, but as soon as it was on a compression stroke it would barely turn it over. The engine was tring to fire as the pistons were coming up, otherwords they were fighting each other. Once I adjusted the distributor, it would spin over like a champ.

 

[Dave Cole]

Thanks to ALL, Good ideas from everyone.