Starter internally grounded

[printjunky]

After a bunch of troubleshooting over a no start (but running fine with the handle/rolling start) condition, I've determined that my starter power input has continuity with the case, so when I turn the key, the 12V is just grounding out. I have the case apart, but can't get the windings out yet (will try to soak those giant screws in a penetrant). The insulating sleeve on the input look OK. Anyone know where else to look to see where this might be grounding out? At this moment, I have enough budgeted for (very) badly needed tires, but not for tires AND a new starter.

[SafeAirOne]

Did you measure for resistance or just for continuity?

If I'm not mistaken, the case is the ground on these starters, so continuity between the input wire for the motor itself and the case would not be unusual. However, a constant continuity between the +12v input (big) lug on the starter solenoid and the starter case wouldn't be so good.

[LaneRover]

What about new tires and a rebuilt starter?

[Finbar]

I had trouble with my starter motor as well. The terminal where the power comes in from the solenoid was grounding to the casing. There is a plastic device around this terminal on the inside of the starter that had cracked and broken. I figured it out because the motor terminal got so hot it started melting the rubber boot that goes over the terminal. The bad news is I couldn't find a replacement for the plastic insulator. The good news is that I improvised with other plastic materials and created my own insulator. So far so good.

[printjunky]

About to try taking it apart for a clean and diagnose.