632 starter runaway

[professorbolin]

I have a bobcat 632 with the ford industrial gas motor in it. I purchased a Bosch 16405 starter for it. I bench tested the starter by connecting a negative battery cable to a ground clamp on the front bolt mounting hole. I then placed the positive on the positive pole of the starter with the nut. I jumped the connectors and the bendix engaged, spun the motor over , and only when I released the jumper did the starter stop as it is suppost to. I then put it on the bobcat connected it, and test jumped it with a test wire to see if it was all good. When I took the jumper wire off it still cranked and cranked until I pulled the battery terminal off. when it was cranking, same as the bench test I only had the negative to the bolt hole, and the positive to the positive of the starter no other wires. I thought it was binding, so I shimmed it a half dozen test times and each time it ran away till the battery was disconnected. why does it only run away while bolted to the bobcat and not while bench testing?

 

[jerry]

I had a 632 did that and burned up the starter before I could get the cable off. It's caused by the solenoid sticking , the guy who rebuilt the started said usually erratic or low voltage will make the solenoid do that. Try it with jumper cables directly to the starter in the machine, it may be a fault in the machines wiring.

 

[professorbolin]

I had a 632 did that and burned up the starter before I could get the cable off. It's caused by the solenoid sticking , the guy who rebuilt the started said usually erratic or low voltage will make the solenoid do that. Try it with jumper cables directly to the starter in the machine, it may be a fault in the machines wiring.

I used the same battery and cables to bench test it, and then install it in the machine and then test it with exact same battery and cables. it runs away when installed but not on the bench. must be the load making the solenoid stick. Thank You for your help, I'll install a new solenoid and get back with results.

 

[jerry]

I used the same battery and cables to bench test it, and then install it in the machine and then test it with exact same battery and cables. it runs away when installed but not on the bench. must be the load making the solenoid stick. Thank You for your help, I'll install a new solenoid and get back with results.

After rebuild mine still stuck once so I took it back to the rebuilder and he replaced the new solenoid . Went home and cleaned the cables both ends and fully charged the battery and never had any more trouble. Only other thing I could think of would be if the ring gear on the engine had some bad teeth and would not release the starter drive . Something to look at next although bad teeth generally won't let the starter engage. If you have to take it out again roll the engine by hand and inspect all the teeth , if just a few don't look up to snuff you may be able to clean them up with a file. good luck

 

[professorbolin]

After rebuild mine still stuck once so I took it back to the rebuilder and he replaced the new solenoid . Went home and cleaned the cables both ends and fully charged the battery and never had any more trouble. Only other thing I could think of would be if the ring gear on the engine had some bad teeth and would not release the starter drive . Something to look at next although bad teeth generally won't let the starter engage. If you have to take it out again roll the engine by hand and inspect all the teeth , if just a few don't look up to snuff you may be able to clean them up with a file. good luck

For 29.99 I bought a New solenoid and installed it on the starter and it works perfect. Now on to other problems to fix.

 

[Raurrie]

For 29.99 I bought a New solenoid and installed it on the starter and it works perfect. Now on to other problems to fix.

Hi. Late post but where did you source the starter solenoid from? Looks like I might need one and finding the right part is proving difficult.

 

[mmsllc]

Hi. Late post but where did you source the starter solenoid from? Looks like I might need one and finding the right part is proving difficult.

seek out a local rebuilder where you are. they will be your best bet.