mf 135 starter solenoid

bill wallace · Jun 18, 2009

. i'm trying to get a mf 135 running again. the starter solenoid has two heavy current connections, one to the battery and one to the starter motor. it also has two smaller connections, they look like 10-32 screws with nuts. i can understand the one connection to the starter switch, but what is the other connection for? i paid $75 for a manual, but the wiring diagram in it does not show the two small connections, only the one to the switch.

Bob · Jun 18, 2009

If it is a typical starter solenoid, one small terminal is labeled "S" for "START" (goes to the start switch) and the other is labeled "I" or "R" ("Ignition" or "Ignition Resistor") and it becomes "live" while the solenoid is engaged to bypass the ballast resistor for a hotter spark during cranking.

You didn't say if it's a gasser or a diesel and if it's a gasser I don't know if a ballast resistor is used.

Bottom line if a diesel or a gasser without a ballast resistor you can IGNORE the second terminal.

The other scenario is that is is a special solenoid with both ends of the coil brought out to the two terminals. THAT makes things more complicated depending upon how the tractor is wired (safety switches, if any).

Where did you get the solenoid? Part #?

bill wallace · Jun 18, 2009

. shes a perkins diesel, but i doubt its the original starter/solenoid. i will take a mirror out and see if i can see identifiers on the terminals, and get a part number off the solenoid.
. it was 101 degrees when i was checking it, and my enthusiasm waned a bit.
. thanks much for the comment, i appreciate it.

Greyhorse · Jun 21, 2009

I"ll try to go look at my 135 tomorrow and see what it looks like at the starter. The only safety switch on the mf 135 is the range selector, needs to be in neutral to start.

bill wallace2 · Jun 21, 2009

. thanks. my manual shows the neutral safety switch between the start/heat switch and the starter solenoid. i like the idea of putting it in the ground side of the coil solenoid, that way we couldnt jump start it if it was in gear. all that would of course depend on the low side of the solenoid coming out to a terminal instead of being internally grounded.
. this tractor was substantially modified electrically, i suppose as parts broke they were bypassed. i have a new start switch coming, as it does not have one now, but it will be a few weeks before i get back to the farm to get it installed.
. speaking of heat, how cold does it need to get before i need to start using heat? 40 deg f?
. thanks for the note.
bill

Greyhorse · Jun 22, 2009

Mine will start when it's between 15 and 20 degrees without help, helps to hold the clutch down when it's that cold which it rarely is here.

Greyhorse · Jun 22, 2009

Ok, my mf 135 (also Diesel) has the large positive wire on the large terminal in the middle along with a smaller black wire to the same terminal. Another small green wire goes to the small terminal that is on the engine side of the solenoid. The other small terminal has nothing on it. I think that it's the original starter (Delco Remy) tractor was purchased new by a great uncle in 1967, my dad purchased it at an auction after my great uncle died in the mid 70's and I'm sure he hasn't done anything to the starter.

bill wallace · Jun 22, 2009

. . ok i"m going to expect something to happen if i put 12 vdc on that terminal, then. thanks for checking this.
. . the switch should be here soon. i"m going to make sure that the neutral safety switch is part of the circuit.
. . thanks again for the info

bill

mf 135 starter solenoid

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