Massey 135 Starter wiring

[MasseyConfusion]

I have a Massey 135. It has been converted to 12 volts and has worked fine for the 15 years I have owned it. The wires from the keyswitch overheated and all insulation burnt off the igntion and starter wires. The switch then caught on fire. I replaced the solenoid and wires but the starter engages as soon as the key is turned on. I did connect the ignition wire to a junction containing the alternator field,
the fuel gage and the solenoid terminal that also feeds the coil. This may be wrong as that wire had burnt off.

[MasseyWV]

Unless I'm mistaken, I believe all Massey 135 tractors came from the factory with a 12 volt negative ground electrical system.

The wiring will vary somewhat, depending on the year and whether or not your tractor is a gas or a diesel, but here is a basic wiring diagram for a mid to late 1960's Massey 135 gas tractor with the starter circuitry highlighted in red. Note that this wiring diagram is for Massey 135 tractors equipped with a generator rather than an alternator, but the starter circuitry is basically the same for all of them.

[MasseyConfusion]

First, thank you for your answer and schematic. My tractor has an alternator so the voltage regulator is where a previous owner has connected all the wiring together. I'll sort that out and see what I have done.

[MasseyWV]

First, thank you for your answer and schematic. My tractor has an alternator so the voltage regulator is where a previous owner has connected all the wiring together. I'll sort that out and see what I have done.

You're welcome. Unfortunately, I only had a diagram for a Massey 135 equipped with a generator because that's what mine has, but I'll keep looking to see if I can find a diagram for a later one equipped with an alternator. Alternatively, someone else who has one may eventually reply.

One thing I want to point out for safety's sake, is that no matter what you do make sure that the safety starter switch (#13 in the diagram) is connected and functioning correctly so the tractor can't be accidentally started while it's in gear.

[MasseyConfusion]

The safety starter switch is nowhere to be found. There are also no fuses on anything.

[MasseyWV]

The safety starter switch is nowhere to be found. There are also no fuses on anything.

The neutral safety start switch is located at the front of the transmission bell housing, on the right as if you were sitting on the tractor. The switch should be covered with a rubber dust boot with two wires coming out of it and is engaged/disengaged by the hi/low shifter, where it will only allow the tractor to be started if the shifter is in neutral.

My tractor is a little different than yours, but the neutral safety start switch should be in the same location. Here's a picture showing it's location.

[MasseyConfusion]

Yes, you are correct. My 135 is different than yours, mine is a 3cyl Perkins gas.
The neutral safety start switch is where you have shown, I have often wondered what it is. It is not connected to anything.
I'll test it. I'd like to put it back in use ASAP.
I'm still having the original problem of the starter engaging when the key switch is in run. I did change the solenoid thinking that it may have stuck and caused the overheating, now my question is:
Does the Solenoid S terminal go to the S on the keyswitch and the B terminal to the coil?
What is the wire off the B terminal that goes back to the ignition?
I'm seeing information that the B terminal sends a boost to the coil for startup then the other wire takes it from there. Is this correct thinking?

[MasseyWV]

Yes, you are correct. My 135 is different than yours, mine is a 3cyl Perkins gas.
The neutral safety start switch is where you have shown, I have often wondered what it is. It is not connected to anything.
I'll test it. I'd like to put it back in use ASAP.
I'm still having the original problem of the starter engaging when the key switch is in run. I did change the solenoid thinking that it may have stuck and caused the overheating, now my question is:
Does the Solenoid S terminal go to the S on the keyswitch and the B terminal to the coil?
What is the wire off the B terminal that goes back to the ignition?
I'm seeing information that the B terminal sends a boost to the coil for startup then the other wire takes it from there. Is this correct thinking?

On most starter and ignition systems I've seen, B=Battery, I=Ignition, and S=Starter.

Since your wiring seems to have been modified and was clearly damaged, there is no way to know exactly what goes where so it's best to work from an original wiring diagram whenever possible. That said, here is a wiring diagram for a Massey 135 tractor equipped with a Perkins 3 cylinder gasoline engine and an alternator.

Since wiring diagrams can often be hard to follow, I've highlighted the power (red), starter (blue), and ignition (green) wiring circuits. Note that this forum automatically scales images for viewing which can make things a little hard to see, so I've also included a direct link to the full size image of the wiring diagram.

http://i48.tinypic.com/vzbjnk.jpg

[MasseyConfusion]

Thanks MasseyWV,
Done and running. I went over the whole diagram. The solenoid starter wire had short under the battery. There are no fuses anywhere and a headlight wire was shorted there also.
There are fuses on the ignition and light wires now. I could not have worked through this without the diagram as all my wires are red. I looked at your rebuild pics, nice job.

[MasseyWV]

Thanks MasseyWV,
Done and running. I went over the whole diagram. The solenoid starter wire had short under the battery. There are no fuses anywhere and a headlight wire was shorted there also.
There are fuses on the ignition and light wires now. I could not have worked through this without the diagram as all my wires are red. I looked at your rebuild pics, nice job.

You're welcome. Those shorts are probably what caused the wiring to burn up but I'm glad you got it fixed. When the time comes, I plan to add fuses to my Massey 135's wiring as well.