108s won,t start when warmed up with key, but fine when cold

huib

New member

Equipment
108s
Oct 25, 2014
5
0
1
canada
I have a 108s which will start in the coldest weather, but once it warms up, is will only start with a screwdriver, if it is cold out and sits for a while it will start again with the key, when started with a screwdriver the red little engine light comes on, but doesn,t seem to affect anything
 

Dave_eng

Well-known member
Lifetime Member

Equipment
M7040, Nuffield 465
Oct 6, 2012
5,236
1,018
113
Williamstown Ontario Canada
I have a 108s which will start in the coldest weather, but once it warms up, is will only start with a screwdriver, if it is cold out and sits for a while it will start again with the key, when started with a screwdriver the red little engine light comes on, but doesn,t seem to affect anything
Please clarify........... does the engine turn over but not start or does it not turn over?

Dave
 

huib

New member

Equipment
108s
Oct 25, 2014
5
0
1
canada
it fires right away, it just klicks with the key once it has been running for a while, there is no power going to the solonoid once it has warmed up, I tested the wires, something wrong between the key switch and the solonoid, and it is temperature related ,somehow
 

Dave_eng

Well-known member
Lifetime Member

Equipment
M7040, Nuffield 465
Oct 6, 2012
5,236
1,018
113
Williamstown Ontario Canada
Do you have a WSM? You can download a free one here.

M108S WSM

I think you should take the time to rule out the most basic items. Battery cable, cable ends and cable ground to engine.

If you have a battery cable end that is like this one below, then buy a new cable if for no other reason than to eliminate it as the cause.

forum battery repair.jpg


On page 425 of the WSM you will find the starter troubleshooting section which I have provided below.

forum M108S starter.jpg


I know you said power is not reaching the starter solenoid trigger terminal. Have you measure this with a volt meter. Sometimes tired safety switches put enough resistance into the circuit so that the starter solenoid is not triggered but a reduced voltage is actually reaching the solenoid.

Dave
 

huib

New member

Equipment
108s
Oct 25, 2014
5
0
1
canada
Do you have a WSM? You can download a free one here.

M108S WSM

I think you should take the time to rule out the most basic items. Battery cable, cable ends and cable ground to engine.

If you have a battery cable end that is like this one below, then buy a new cable if for no other reason than to eliminate it as the cause.

View attachment 61832

On page 425 of the WSM you will find the starter troubleshooting section which I have provided below.

View attachment 61833

I know you said power is not reaching the starter solenoid trigger terminal. Have you measure this with a volt meter. Sometimes tired safety switches put enough resistance into the circuit so that the starter solenoid is not triggered but a reduced voltage is actually reaching the solenoid.

Dave
 

Henro

Well-known member

Equipment
B2910, BX2200, KX41-2V mini Ex., Beer fridge
May 24, 2019
5,783
2,969
113
North of Pittsburgh PA
Do you have a WSM? You can download a free one here.

M108S WSM

I know you said power is not reaching the starter solenoid trigger terminal. Have you measure this with a volt meter. Sometimes tired safety switches put enough resistance into the circuit so that the starter solenoid is not triggered but a reduced voltage is actually reaching the solenoid.

Dave
Since the OP is starting the tractor with a screwdriver without issue every time it will not start normally when hot, it sure sounds like the issue is in the safety interlock circuit and not related to the battery circuit supplying power to the starter, or to the ground circuit for the starter.

It is great that the WSM is available, at the link Dave (y)provided.