Farmall 300 + & - AGAIN!!!

[Kelly in tx]

Again, it has an alternator. I changed the cables so it is negative ground. It did a rapid clicking sound when I attempted to start/crank it. I figured the solenoid was/is bad. Went to town and bought a new one & installed it. When I try to attach the switch/start (positive) cable to the battery, it sparks. What is going on?

 

[Dieseltech]

Did you do a load test on the battery? If it checks good then check all the cable ends and connections. I had TWO twelve volt batteries die OVERNIGHT last summer, good one day, shot the next when checked with the load tester.

 

[used red MN]

Probably should have been clearer in the reply to your other post. I used the word “probably” there which means it is probable or a possibility that it has been converted to a “negative” ground. Did it seem like you had to jostle the cables around to get them to fit for the negative ground? Did you buy it with a 12 volt conversion? How long ago, there are positive ground alternators available, but only seemed to have more suppliers of them in the last 8 -10 years. The rapid chattering of a solenoid usually is the sign of a battery with a low charge. Disconnect the wire off of the terminal on the alternator and see if it still sparks when you try to connect your cables. Apparently before changing the solenoid the battery connected fine as a negative ground with no sparking but the rapid chatter was the result when trying to start it? Where did you get the solenoid, part number of it? These 12 volt wiring conversions can be wired multiple ways and work “okay” but only a couple of ways are correct. Photos of what alternator you have and of the wiring at the solenoid may help. Does any of the wiring look like it may overheated, melted insulation etc.?

 

[BarnyardEngineering]

Rapid clicking sound is usually a bad battery connection. Should have checked that before throwing parts at it. Probably a cheap fix.

Alternators are almost always negative ground.

What is going on? Maybe nothing. A single small momentary spark is nothing to worry about. If the key is on it's most likely the ignition coil charging. Take the cable off, touch it again, no spark, you're okay. A big scary snap and black marks, or lots of sparking and "welding" noise is the sign of a short circuit.

It didn't spark before you changed the solenoid, right? If it's making big scary sparks you hooked up the solenoid wrong somehow.

 

[wore out]

Rapid clicking sound is usually a bad battery connection. Should have checked that before throwing parts at it. Probably a cheap fix.

Alternators are almost always negative ground.

What is going on? Maybe nothing. A single small momentary spark is nothing to worry about. If the key is on it's most likely the ignition coil charging. Take the cable off, touch it again, no spark, you're okay. A big scary snap and black marks, or lots of sparking and "welding" noise is the sign of a short circuit.

It didn't spark before you changed the solenoid, right? If it's making big scary sparks you hooked up the solenoid wrong somehow.

It's also possible the new solenoid was defective or was damaged by one of the large copper studs rotating a bit in the plastic housing when the O P wrenched down on the nut.