1955 HD9B w/Detroit Diesel - Starter Removal

 F Y I; Free up the engine emergency kill flapper on charger intake before U try to start it. 

You would be much better removing the starter from the engine and taking it apart than trying to "burnish" the commutator segments with it in place. It is probably a 40MT series starter and they are a bit heavy and awkward to handle so be prepared for about 35 pounds of dead weight once you start removing the three fasteners retaining it to the flywheel housing. There are both four brush, and eight brush variants of this starter and both work the same and on a bench the commutator and brush faces and commutator segments are easily cleaned up. At the same time when the starter is removed, take the solenoid apart also and address both it's contacts, and copper ring as these burn and carbon track with usage. They can be the source of no starter engagement but if you are getting no response at all, and you prove voltage coming from starter switch, and grounds are good, this is where to look first.

I've done a lot of these myself but anytime I pull a starter or alternator anymore it goes in for rebuild. I don't have a growler for testing, and cannot cut a commutator for proper segment depth so this is best left to someone in that game. There are two or three different sizes/styles of bushings in both the starter nose housing, and end plate and these should be evaluated as both wear with use. I've found many times over the years it can be difficult to beat someone at their own game.

Should you decide to do this, (and it's easy generally) do not use emery cloth for your abrasive. It is conductive and can cause things to go haywire as it's electrically conductive. Use either aluminum oxide, silicone carbide, or flint paper to clean your electrical components. A good spray of electrical contact cleaner to rinse away any filings is always good too.

I believe what Chris was referring to is the DD tendance to over speed themselves  after siting for years. The flapper cuts off air. Many of the old guys want the precleaner off the air cleaner pipe and good piece of wood to set across it if it starts running away. So easy to be ready, so much scrap metal if your not.