How to Rebuild Outboard Starters

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The electric motor that starts your outboard may require, at some point, an overhaul. While, much of the process of rebuilding a starter motor is a cleaning process, most of the work involves ensuring the electrical windings, brushes and commutator are in good working order. With a multimeter, a few tools and cleaners, both electrical and mechanical, you can effectively give your outboard a new starter. If you must replace parts, though, consider the cost of the parts against the cost of a new starter motor.

Items you will need

  • 1/4-inch open-end wrench

  • Micrometer

  • 300-grit emery cloth

  • Multimeter

  • Canned, compressed air

  • Acetone

  • Electrical contact cleaner

Step 1

Remove the four bolts securing the starter housing and armature face, using a 1/4-inch open-end wrench. Remove the starter housing. Inspect the permanent magnets in the starter housing for damage, debris or corrosion. Clean, as necessary. A damaged magnet requires starter housing replacement. Compare the brush springs for color and length. Replace the springs if they are either stretched or have a bluish color.

Step 2

Wrap the jaws of a vise in a dish cloth. Secure the armature in the vise, with the jaws just tight enough to keep the armature from moving. Measure the depth of each mica undercut on the commutator, using a micrometer. Each undercut must be more than 0.008 inches. If not, replace the commutator.

Step 3

Inspect the pinion drive for damaged teeth. Replace, if necessary. Visually inspect the splines of the armature shaft for damage. Spin the pinion drive onto and off the splines, and replace if the pinion drives does not move easily.

Step 4

Polish the commutator surface, using 300-grit emery cloth. Place one probe of a multimeter on the commutator shaft and one on the core to check for continuity, indicating a short. Move the probes between the segments, where continuity should exist. If it does not, open circuits exist. If either a short or open exist, replace the commutator.

Step 5

Place one multimeter probe on the positive side of the brush plate ground and one on the brush plate. Continuity must exist. If it does not, replace both the brush plate grounds. Blow debris from the armature and commutator cover using canned, compressed air.

Step 6

Clean all of the components, except the brush plate and brushes, using a mild solvent such as acetone. Clean the brush plate and brushes with electrical contact cleaner.

Step 7

Reassemble the overhauled starter.

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