Howdy, Trying to resurrect my Grandfathers JD 450B Crawler/Loader which has been sitting for 8 years. After Turning the ignition to on, and initially hitting the starter button, it will continue to crank until the batteries are disconnected. Burned the one positive terminal lead completely off. Suspecting a faulty starter button, i opened the dash and found a rats nest behind the instrument panel, cleaned it out and then disconnected the 2-wire connector from the back of the starter button and used a jumper wire instead. Same problem. After disconnecting the batteries, it resets itself and will not crank until power is supplied to the starting circuit, but then will not stop cranking. Any suggestions? Anyone know where I can get a wiring diagram for the starting circuit? Im not what you would call a heavy equipment mechanic but have a fair degree of mechanical aptitude.... Faulty starter relay? Solenoid sticking? Any ideas or insight would be greatly appreciated!! Thanks, Bryan...
Disconnect the signal wire for cranking from the starter. Check for power (should not be any voltage). Then turn the key to the start position and check voltage, you should now have 12 volts at the signal wire. Let off the starter button and see if you still have 12 volts there. If you still have 12 volts with the button released, it means you have an issue in the circuit, not the starter.
I would guess the starter drive is rusted up and not allowing the solenoid to release which keeps the starter motor energized. Check Dmax's suggestion first, if your problem isn't electrical, then the starter should come off.
There is a round contactor plate in the solenoid that slams into contacts to make the connection to activate the starter motor. They are steel to steel contacts. When you have low battery amperage, it will melt the two together causing your symptoms. When voltage is removed, the spring pulls the contactor back breaking the tiny weld that held them together. This is why you don't want to use batteries that are discharged to try to start a tractor. Over time it will melt little craters in the contactor eventually causing problems like you have because the plunger can't get a nice flat connection with the contactor plate. It is only touching on the high spots, like moon craters. There are repair parts on Ebay, Amazon, or your local starter repair facility to solve the problem. You can see the round contactor here in the first pic. If you look at the second pic, you can see the flat contacts on the back of the battery and motor studs. http://www.ebay.com/itm/66-1204-DEL...ash=item234f6a796b:g:ZmQAAOSwcwhVNYUI&vxp=mtr If you were to take one apart, you'd see how a starter solenoid is really low tech. I don't remember which starter was installed on the 450B, but I'm pretty sure it was a Delco.
May be a little fussy here but they are not steel to steel. Might you have meant to say metal to metal? Everyone I have seen in 40+ years has been copper, some are plated with something silver colored but they are copper underneath. In a pinch you can disassemble them, flip the disc part over and take a fine file to the square head of the contacts in the cover.
Thank you fellas for all the info. I will be tearing into it and will keep you posted on how I make out.
Yes they are not steel, it didn't even register when I linked the pics...and that bacon frying sound you hear when your batteries are almost dead is not good on them. I have always thought the disc was a mix of something else.