We have an old diesel tractor that's been giving me an ulcer. It cranks slow as if the battery were dying then turns over like nothing is wrong a few days later. It turned over slow all weekend in spite of having a freshly charged nearly new battery. I had to drag it out of the hay shelter with our other tractor as it was blocking access to some round bales. When I got home this evening I tried the key and it fired right up as If nothing were wrong.
When it turns over slowly it draws the battery down to 8v and smoke comes from the starter terminal. I've cleaned all the terminals and tried connecting the starter directly to the battery with jumper cables. I'll assume the starter is pooched and needs to be rebuilt but why is this a random intermittent problem?
In reply to Wayslow :
A bad spot on the rotor or stator, maybe? When it stops in a certain position something is causing it to short out & pull a huge current draw.
Pete Gossett said:
In reply to Wayslow :
A bad spot on the rotor or stator, maybe? When it stops in a certain position something is causing it to short out & pull a huge current draw.
I thought that too but even if I just bump it, when it's having a slow crank episode, it continues with the same symptoms. If it were a just a bad spot, on the commutator, I should've got past it. Generally a bad spot also just shows up a dead spot.
I guess I should add that it's a British build 1967 International 434. Electrical issues are to be expected.
I have no idea. But I read smoke from the starter and assume something isn't right inside. Bad fiber washers allowing occasional contact between things that are hot and things that shouldn't be?
At least we can be pretty sure nothing electrical outside the starter is causing it to smoke and turn slowly...
Vigo
MegaDork
3/2/20 9:59 p.m.
Does it have a solenoid built into it? Slow and smoking means excess resistance somewhere IN the starter, besides the rotor. You basically have brushes and whatever they hook to, in that case. The available voltage is going to get converted by the resistances into whatever they convert it to. When a motor is working properly it converts most of it to motion. When pretty much anything electrical has unintended resistance, it pretty much always just converts it to heat. The resistance could be on either the power or ground side inside the starter. If it has a solenoid on it there's a large contact plate in there that gets crappy surfacing. If it's the ground side, the negative brush grounds to the starter case somehow.
But it kinda doesn't matter unless you plan to rebuild it. The fact that when the starter is slow there is smoke coming out of it means the unwanted resistance is IN the starter, and replacing it with a good starter should fix it.
