How to replace a starter motor

A starter motor that is too slow, lacks power, or doesn’t do anything at all? Time to replace it. You can do this job perfectly well yourself. First of all, safety is of the essence. Make sure that the mass switch and/or the battery cable is disconnected. The starter motor is usually located near the crankshaft on the side of the flywheel housing.

How to replace a starter in 3 steps

Follow these 3 steps to replace a starter yourself: disconnect, dismantle and find.

1. Disconnecting

Disconnect the electrical system, disconnect the battery or mass switch, and check that the cables are indeed not live.

In conventional starter motors, one thick cable runs directly from the positive battery terminal to the incoming copper bolt on the starter relay (Terminal B or 30). This is often also the distribution point for the rest of the electrical system. In other words, there may be more than one cable, so mark them well.

The starter relay is controlled by a smaller cable (terminals S or 50). Also disconnect this cable. Some starter motors are “mass free”. This means that the entire installation is free of mass (often the engine block), so these cables have to be disconnected too.

2. Disassembling the starter motor

Since the starter motor is disconnected from the electrical system, it can now be taken off the engine. Generally speaking, it is attached to the flywheel housing with 2 or 3 bolts. Accessibility is not always ideal, especially not in a tight engine space, so it may require some creative socket wrench and extension work.

3. Searching for the right starter motor

You can easily search for the right alternator on our website. The easiest way to select a starter is by the number. The number is often printed on a label or engraved on the housing. You can put this number in our search bar, for instance. Alternatively, search for the make and model of the boat engine in the “starter motors” category. The dimensions and specifications of each starter motor are shown. The most important criteria in any case the dimensions A and B in the drawing. Below are examples of some brands and product numbers.

And finally: the installation of the new starter

The installation of the new starter is carried out in reverse order to the steps described above. Make sure that all surfaces are corrosion-free and clean. N.B.: Grease is not conductive. You should therefore always grease the material after installation. This acts a protective layer against moisture penetration. For proper protection between the contacts, use contact spray or conductive paste.

Some facts about starter motors

The rotation is generally indicated at the front of the starter motor:

1. CW = Clockwise
2. CCW = Counter Clockwise
3. DD = Direct Drive. These are older and heavier models of starter motors that drive the gear wheel directly through the engine.
4. GR (gear reduction) = Later model starter motors with a planetary reduction. These starter motors are lighter and more compact to produce.

To buy a starter motor

At AB Marine service you can buy (replacement) starters from:

• Bosch
• Delco Remy
• Denso
• Duccelier
• Femsa
• Hitachi
• Iskra
• Lucas
• Magneti Marelli
• Magneton
• Melroe
• Mitsubishi Motorolla
• Paris Rhone
• SEV
• Valeo
• Visteon
• OEM

More information about the electrical circuit and circuit testing the installation?

For more information about the electrical circuit and circuit testing the installation, please read: Starting problems? 3 tips to fix.