How to Clean Your Direct-Drive Engine Starter

Many starters manufactured by Prestolite and Electro Systems are in use with Lycoming engines. From time to time, these starters used on our direct-drive engines are returned to the factory reported as malfunctioning, but investigation here revealed the problem to be dirt. The location of the starting motor on many aircraft engines subjects the Bendix Drive of the starter to contamination from dust, dirt and moisture because the drive housing is open, and the engine constantly circulates air around the starting motor.

Typical indications of a dirty Bendix Drive are:

1. Sluggish operation – operator has to make several attempts before the starting motor will crank the engine.
2. Noisy operation – a grinding noise when the starter is energized.
3. Failure to engauge.

Whenever any of the above complaints are received, the starting motor should be removed immediately and the Bendix Drive cleaned and lubricated. Oil should never be used, because oil in that location collects dust and dirt, becoming gummy and causing the Bendix Drive to stick.

In most cases, it will be necessary to partially disassemble the starting motor in order to service the Bendix Drive. The latter should be removed from the motor shaft to ensure thorough cleaning and lubricating. Clean the area in front of the Bendix Drive pinion before removing the drive from the shaft.

Do not use carburetor cleaner or any solvents that could damage the rubber block inside the Bendix Drive. Use only clean petroleum base cleaners such as kerosene or varsol.

Thoroughly clean the Bendix Drive to remove all dirt and contamination from the screwshaft threads and control nut. If the drive is exceptionally dirty, the drive pinion cup can be removed to ensure a thorough cleaning job. Do not attempt to remove the control nut.

After the Bendix Drive has been thoroughly cleaned and blown dry with compressed air, lubricate the screwshaft threads and ratchet with a silicone spray. Lubricate the motor shaft with the same silicone lubricant before installing the drive assembly on the shaft.