Bobcat 742 stays quiet

[DeWong]

I just had the 1984 machine. After I jump started it, it ran well for 3 hours and everything looks normal. When I finished the work, I could not turn it off with key. So, I stopped it by disconnecting the battery negative wire. I jump started it again next day, it ran with less power. The battery indicators pointed to 10 volts range when it's running. After less than 30 min, it shut down by itself. Since then, I can not start it any more. No crack sound at all even when it's connected to a jumper. Please give me suggestions where to start.

 

[Tazza]

I'm wondering if the battery is flat. If you had to jump it to start, the alternator may not have been charging the battery, that's why it's not working when you jump it now.

 

[OldMachinist]

I'm wondering if the battery is flat. If you had to jump it to start, the alternator may not have been charging the battery, that's why it's not working when you jump it now.

Sounds like the diode in the wiring harness that keep the alternator from back feeding the ignition system. If it goes bad power from the alternator keeps the engine running but also will drain the battery with the engine not running.

Disconnect the alternator and charge the battery. Then try running it to see if it shuts down when you turn the key off.