You pull the starter off of your Mercruiser (GM manufactured 5.7L) I/O and take it to the nearest auto parts supplier for a replacement. The starter for a car looks exactly the same as the one you just removed from your marine engine. You think to yourself, “I wonder how much difference there REALLY is between the marine and the automotive starter.”
Don’t be fooled by the fact that an automotive starter will bolt on to your marine engine. A marine approved starter has better seals and gaskets to keep water out. It also contains more corrosive resistant materials.
However, the primary consideration is safety, as there are deliberate design differences to contain sparks that could ignite fuel vapor in the bilge. In an enclosed engine compartment, where volatile fumes exist, any stray spark could cause a catastrophic explosion, resulting in severe injury or possible death. In order to prevent this, a marine starter is constructed with internal shielding to contain any sparks or stray electricity that could travel into the bell housing or bilge where gasoline fumes may be present. Another benefit from this shielding is that it protects the back half of the starter motor from moisture and contaminants which WILL decrease the life of the starter.
If the replacement starter you are buying does not have a tag or sticker on it that states it has been manufactured to SAE J1171 standards, you should ask if the product really is an approved marine grade product. You should always make every attempt to be sure that you are not being sold an automotive starter for your boat. In order to receive this certification, the manufacturer of this starter must submit a sample to pass three separate tests, each of which is performed fifty times. The tests include operation in an enclosed explosive atmosphere, high temperature tests and induced ignition tests.
Please remember the following:
- Using anything electrical that is not marine rated is BOTH illegal and dangerous
- The Coast Guard WILL ticket you for noncompliance
- The risk of injury or death is incrementally higher when you elect to use automotive electrical parts on your marine engine
Stay safe out on the water and if you have any questions as to which start is best for your marine engine, call our Technical Support Line at 1-877-663-8396.