October 2nd - Starter Motor Overhaul

Another busy day tinkering with green things. For a while now, the Hotchkiss Jeep has had a starter motor problem. When the starter button is pressed, the starter spins, but the Bendix gear isn't thrown forwards to mesh with the flywheel. It's something that happens every couple of years as a result of use and wear. The starter is at the bottom of the engine bay, so the rear battery, dizzy cap, and coil had to ome out to get access to the mounting bolts. Once out, it was taken to the workshop to strip down.
 

 
The end cap and main body were removed first to access the commutator. As I've found before, it was filthy. The surface was cleaned up with some fine wet and dry paper, wrapped around a small wooden block. The surface has some pitting, but I'm not sure the shaft will fit in my small hobby lathe to true up the surface. So for the time being, I just clean up the surface.
 

 
It was cleaned up back to copper and the gaps between the contacts cleaned out with meths and a cotton bud. The Bendix gear was removed next and washed down to remove grease and dirt building up in various locations.
 

 
When the Jeep was upgraded in 1966 to the NATO 24 volt standard, the Hotchkiss starter motor also had a starter solenoid fitted. This takes the starter current rather than the switch and also mechanically throws the Bendix gear out and pulls it back via a spring. That was all cleaned too. I had hoped to replace one of the copper threaded contacts on the solenoid, as the end of the threads were slightly stripped. Despite my best efforts, it wouldn't move, so I left it alone for fear of shearing it and making the solenoid useless. Putting the starter back together in the past was a challenge.
 

 
You need to hold the brushes out of the way of the commutator to put the end cap on. However, the wires aren't long enough to leave a gap big enough to get fingers or any tools in to hold the brushes. I solved this many years ago by drilling two tiny holes in the end cap and inserting two small metal pins to hold the brush springs back. Once the end cap is in place, the pins can be withdrawn, allowing the brushes to spring towards the commutator.
 

 
The starter motor was bolted back in place and all the other engine components refitted. One last small job was to repair the cylinder head temperature wire. At some point before I got the Jeep, the insulation had fractured and it had been taped up. The insulation was quite hard and the wire was starting to break at the point where the insulation failed and also at the spade terminal joint. I cut the wire and soldered some new silicone wire in place, using some heat shrink tube to form a strain relief across the soldered joints.

I gave the Jeep several test starts and the starter motor behaved for each one ( see the video below ). On the last start of the session, I left the engine running for a while to heat up to check the cylinder head temperature gauge was receiving a signal from the sensor.