Electrical problem

[macec3(TX)]

5610 Ford Diesel. This morning I tried to start the 5610. Battery was weak and would just roll engine over slowly. Turned key off and starter stayed engaged as if the key was still on. Got wrench and pulled negative cable off battery. Put new ignition switch on and still had same problem.
If the ignition switch is OK, what would make the starter stay engaged and try to start the tractor?
Could this be caused by a weak battery?

 

[JMOR]

(quoted from post at 18:47:05 12/16/13) 5610 Ford Diesel. This morning I tried to start the 5610. Battery was weak and would just roll engine over slowly. Turned key off and starter stayed engaged as if the key was still on. Got wrench and pulled negative cable off battery. Put new ignition switch on and still had same problem.
If the ignition switch is OK, what would make the starter stay engaged and try to start the tractor?
Could this be caused by a weak battery?

es, weak battery makes starter current high enough to try to weld solenoid contacts together. Next time it happens, whack the solenoid with heavy tool or small hammer....it will usually release.

 

[David G]

I would agree, high current probably welded contacts on solenoid with weak battery.

 

[RodinNS]

Solenoid contacts are welded. Could have been the original problem... poor connection made it draw hard and stuck them. If it's got a Lucas original starter I'd probably clean the commutator and brushes and replace the solenoid/switch. If it's got a cheap knockoff starter I'd probably just replace it.

Rod

 

[macec3(TX)]

New battery. Works like new again. Thanks guys.

 

[Texasmark1]

Just had the same problem with a 4 cyl 2000D. I thought the contacts were permanently welded. I attempted to get a new one but none available. Put in new battery and as with you fixed the problem. Since then I have replaced the solenoid to prevent future problems.

Nothing like cold weather to sort out your loafing batteries.

Been awhile but as I recall, the weak battery doesn't let the starter spin fast enough to develop enough of what's called Counter EMF. Counter EMF bucks the applied voltage and limits current in a spinning motor. Like continuously having inrush current like you get for a second or two when normally starting a motor. Therefore, even though the battery was low, the contact current was high and thus the welding.

Mark