starter motor rebuild

[drz400]

since leaving my major over the winter the starter motor has given up. It was slow last year. can I buy the bits to rebuild it myself and what parts should I change.

[oehrick]

At the risk of being shot down in flames, have you bridged the High Current studs on the solenoid with say a sacrificial open ended spanner, to exclude the starter or ignition switches and solenoid coil or wiring as being at fault ? Likewise have you actually dropped the motor directly across the battery using jump leads ? if either of these promote movement from the motor, check elsewhere first (dry joint, bad earth etc)

If you have tried these with no result, I can't see anything glaringly obvious from your photos as a lead, the com looks a lot better than many I've seen and no obvious signs of overheating around the brushgear, although there is a line around one of the brushes it might be worth checking they are both free to move in the holders, one hanging up might account for weakening effort then stopping but would anticipate arcing being present before.

Mechanically as long as the 'Bendix' (I know its not) pinion moves as it should on the lever and bearings are free, it sounds like some electrical connection may have given up the ghost or a field coil fault perhaps - which are easier to check with a meter than all those comutator strips.

Happy hunting

[Brian]

I would second everything Rick says, your commutator and brushes look better than many I have seen. The most likely problem is field coils breaking down but do check size of battery cables, are they getting warm? Battery capacity, is it at least a 120 ah?

[henk]

you could check the bearing bushes. Looks like the axle has made contact because you can see groves on the outside.
Wearing of the bush at the end of the alternator gives the same result.

[drz400]

I have tried direct power, additional battery and extra earth lead.

I did notice wear marks and bronze bearings have some wear. Can you buy bearings for each end? Would replacing them be a good start?

The only additional thing I can note is that it wont start except tow start now, but later on after running even hours later it will start on lever?

Thanks for your help.

[oehrick]

Hang on, are you saying that when cold the starter motor turns but not enough to start the engine ?

if so did hot wiring direct to battery help any ?

Have you a second battery in a car or truck to jump lead to the tractor battery, if so does this help ? if it does you may not have the right battery with enough cold dranking amps or whatever they call it these days. if it doesn't it sounds like a motor fault.

Mine is a bit sluggish and I know the pump and injectors are overdue for some TLC, on cold days I warm the fuel pipes into the injectors with a small blowtorch which makes enough difference to fire up. (I don't like ether starts , I was standing far too close to a Turner Yeoman that someone had saturated with the stuff and only just missed one of the conrods which shot through the sump shooting through my leg as well)

[henk]

I had the same sort of problem. Turns out one segment of the battery was bad. When the second part went down, the Major would not start even warm.
Check the battery and bad connections.

I think bushes can still be found on the internet.

[drz400]

Hang on, are you saying that when cold the starter motor turns but not enough to start the engine ?

if so did hot wiring direct to battery help any ?

Have you a second battery in a car or truck to jump lead to the tractor battery, if so does this help ? if it does you may not have the right battery with enough cold dranking amps or whatever they call it these days. if it doesn't it sounds like a motor fault.

Mine is a bit sluggish and I know the pump and injectors are overdue for some TLC, on cold days I warm the fuel pipes into the injectors with a small blowtorch which makes enough difference to fire up. (I don't like ether starts , I was standing far too close to a Turner Yeoman that someone had saturated with the stuff and only just missed one of the conrods which shot through the sump shooting through my leg as well)

Two batteries made no difference

It does not really turnover, cranks a bit then stops, not really a revolution of the engine.

Agree about ether....mine came to me after an ether assisted start....hole in pistons and damaged head...so I fully rebuilt it a few years back.

I feel its starter, its like a bad earth but a direct feed to earth makes no difference?

[drz400]

.

I think bushes can still be found on the internet.

I will try to find the bushes if not I will have to make some

[oehrick]

Sounds like you probably need to take it somewhere to have it looked at, unless you have and know how to use a 'Growler' to check the com out, a straight continuity test on the field coils with a bulb and battery or multimeter if you have one available might locate a field coil failure.

If you do have a voltmeter handy and haven't lost the will to live yet, you could try the following

Measure voltage over battery terminals (keep a note of this and subsequent readings as vee may haff kvestions later )

Clip it across across the ground connection at the motor and the battery connection stud of the solenoid - should read the same as across the battery. (if not find why) Bridge the starter switch on the motor with a bit of wire so the motor spins without the pinion engaging, you should see a voltage drop and hear the motor spin, note the reading then repeat on the lever so the motor is under load

Move the meter lead from battery side to the motor side stud on the solenoid and repeat the pinion out & pinion engaged tests.

Oh and just to exlude solenoid coil, if you have one with the rubber boot where you can manually actuate the sol you could try that as well

I would expect the voltage with pinion out to be higher than when under load, if there is a mismatch between the equivalent tests from battery side compared to motor side of solenoid I'd suspect the solenoid, unlikely as two batteries on or jump lead to motor stud you found no difference. We may see something in the readings that rings an alarm bell.

May not help but I find it so easy to overlook something and convince myself I've covered it - my particular blind spot is overlooking ground / earth / return line faults

[Pavel]

I tend my apologies if I am repeating previous suggestions.

Firstly arm yourself with a digital voltmeter. They are more than accurate enough for general electrical diagnostics and are cheap to buy.
Observing correct polarity [is yours positive or negative earth?], place across the battery terminals with it set on DC volts higher than 12. Note the reading -- a healthy battery should at least read out in the mid to high 12s.
Start the engine [even with a tow]. At rest set the throttle at about half total revs, with headlamps on if you have them. The readout should be towards the high end of 13 volts.
If neither of these tests are close to the above voltages, you have a problem -- either battery or generator.
Next, with the engine OFF connect your volt meter between the earth terminal [positive or negative??] and the BODY of the starter motor. Operate the starter [you need 2 pairs of hands for this or a willing volunteer]. Any reading above half a volt indicates a bad earth return. (I have found that fitting star washers between earth connectors/terminals and the engine block and chassis rails makes an excellent connection -- it cuts through surface rust and paint)
You could, of course, use jump leads connected to the battery of a running slave engine and the Fordson [400amp ones, not those useless 100amp things]. Operate the tractor starter; if it turns over at a reasonable rate of knots then you know your battery or generator are dicey -- or both.
When I did my automotive electrical course it was stressed that finding the problem was 90% of the work involved -- rectifying it was simple, if at times expensive. So be methodical -- check everything.

Pavel