For the last 3 or 4 years, I have had intermittent starting problems with my BX. It started with the original starter that would engage the solenoid, pushing the pinion out, but the starter motor wouldn't spin. Usually, a tap on the case with a long punch, would make it engage and start the engine. It finally got irritating enough that I bought a new starter off Amazon, installed it, and the problem went away, for a while. About a year or so later, the same problem started again. I had taken the original starter to a local shop and had it rebuilt, so I swapped the starter out and all was fine for a while. But eventually the problem began recurring, again. I had taken the Amazon starter to be rebuilt, so I reinstalled it, but the problem would still recur, usually, but not always on hot restarts.
Here's where it gets interesting. A good friend has a BX that is only a hundred or so serial numbers from mine, also a 2005 model. He has had virtually the same pattern of intermittent starting problems. The original stater lasted over 15 years, and a few months or so after replacing it, the problem started again. He had the same symptoms as I did, solenoid engages, but the starter wouldn't spin the engine. He has been partially disabled with hip and knee problems for the last 9 months, so I changed out the starter for him last November, and recently, it has started acting up again. So, thinking we got a bad rebuild on the starter, I swapped it out again for him.
I took the old starter back to the rebuild shop and expressed my dissatisfaction to the rebuild tech with how often the starters were failing. He listened and said he sees the same problem on other pieces of aging equipment. After getting 20 or so years old, the same problem we were having would show up. He took the cover off the solenoid and pulled the plunger and contact plate out. When he looked it over and showed it to me, the contact pattern were pretty irregular, caused he said, by insufficient voltage to the solenoid. He said that with all the safety switches and connectors in the circuit between the ignition switch and the solenoid, enough resistance builds up that eventually the voltage is insufficient to pull the solenoid solidly and make a good connection between the battery and starter motor terminals, which makes perfect sense to me. He suggested putting a standard automotive 40 amp relay in the circuit, using the start wire to trigger it, and sending current from the battery terminal on the starter directly to the solenoid terminal. This would ensure that the solenoid coil would get full battery voltage and pull the contacts together properly.
He cleaned up the contacts on the starter, put it back together and tested it, then sold me a relay and socket with leads to install on the tractor.
When I got home, I pulled the bonnet off the BX and connected one channel my little oscilloscope to the start terminal on the solenoid, and the other to the battery terminal. When I cranked it, the voltage to the solenoid dropped to just under 8 volts, while the starter was getting about 10.5 volts, so the tech's diagnosis was correct.
Installing the relay was simple. The start wire was connected to one terminal of the relay coil, the other was grounded to the bolt in the frame where the engine ground cable is attached. The common relay terminal was connected to the battery terminal on the starter, and the normally open relay terminal was connected to the solenoid start terminal. I made a mounting bracket out of a piece of 1.25" X 1/8" strap, bolted to the grounding bolt and used a 10-24 SS screw to fasten the relay to the bracket. After securing the new wiring, I gave it a try and it started up, no problem.
Over the past few years, I did replace the safety switches on the high/low trans lever and on the PTO lever, so they should still be in good condition, but possibly the seat safety switch and the rest of the wiring is building enough resistance to cause the problem.
So, it was a simple fix for a recurring, exasperating problem with the starting system.
It's been working fine for the last few weeks with the same starter that was previously having the problem, so I consider it fixed. I have also made up a relay assembly to put on my friend's BX, and will probably install it this weekend. He'll be glad to have his BX fixed too.
Here's where it gets interesting. A good friend has a BX that is only a hundred or so serial numbers from mine, also a 2005 model. He has had virtually the same pattern of intermittent starting problems. The original stater lasted over 15 years, and a few months or so after replacing it, the problem started again. He had the same symptoms as I did, solenoid engages, but the starter wouldn't spin the engine. He has been partially disabled with hip and knee problems for the last 9 months, so I changed out the starter for him last November, and recently, it has started acting up again. So, thinking we got a bad rebuild on the starter, I swapped it out again for him.
I took the old starter back to the rebuild shop and expressed my dissatisfaction to the rebuild tech with how often the starters were failing. He listened and said he sees the same problem on other pieces of aging equipment. After getting 20 or so years old, the same problem we were having would show up. He took the cover off the solenoid and pulled the plunger and contact plate out. When he looked it over and showed it to me, the contact pattern were pretty irregular, caused he said, by insufficient voltage to the solenoid. He said that with all the safety switches and connectors in the circuit between the ignition switch and the solenoid, enough resistance builds up that eventually the voltage is insufficient to pull the solenoid solidly and make a good connection between the battery and starter motor terminals, which makes perfect sense to me. He suggested putting a standard automotive 40 amp relay in the circuit, using the start wire to trigger it, and sending current from the battery terminal on the starter directly to the solenoid terminal. This would ensure that the solenoid coil would get full battery voltage and pull the contacts together properly.
He cleaned up the contacts on the starter, put it back together and tested it, then sold me a relay and socket with leads to install on the tractor.
When I got home, I pulled the bonnet off the BX and connected one channel my little oscilloscope to the start terminal on the solenoid, and the other to the battery terminal. When I cranked it, the voltage to the solenoid dropped to just under 8 volts, while the starter was getting about 10.5 volts, so the tech's diagnosis was correct.
Installing the relay was simple. The start wire was connected to one terminal of the relay coil, the other was grounded to the bolt in the frame where the engine ground cable is attached. The common relay terminal was connected to the battery terminal on the starter, and the normally open relay terminal was connected to the solenoid start terminal. I made a mounting bracket out of a piece of 1.25" X 1/8" strap, bolted to the grounding bolt and used a 10-24 SS screw to fasten the relay to the bracket. After securing the new wiring, I gave it a try and it started up, no problem.
Over the past few years, I did replace the safety switches on the high/low trans lever and on the PTO lever, so they should still be in good condition, but possibly the seat safety switch and the rest of the wiring is building enough resistance to cause the problem.
So, it was a simple fix for a recurring, exasperating problem with the starting system.
It's been working fine for the last few weeks with the same starter that was previously having the problem, so I consider it fixed. I have also made up a relay assembly to put on my friend's BX, and will probably install it this weekend. He'll be glad to have his BX fixed too.
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