The water’s wrecking my starter
QI have a boat with a JGM engine based on a BMC 1.5 diesel. I keep getting water in the starter motor. It’s too high for water to get in from the bilge and the engine is enclosed in a box inside the engine room. I removed the bell housing, which was dry, and there’s a drain hole at the bottom. How could water get into the motor?
DEN JOHNSON, via email TONY REPLIES... The water must be from outside. Despite what you say, the most common cause is for bilge or engine drip tray water to rise enough to get through the hole in the bell housing. The level will be way below the starter but the flywheel will throw it up inside the bell housing and into the starter motor. If you are absolutely sure the water is not getting into the bell housing via that drain hole, check the core plugs at the back and starter side of the engine for leaks.
Some 1.5s have the calorifier take-off at the back of the head on the starter side (between the fuel filter bracket and rocker cover). If this is leaking it might allow water to run down on to the starter or into the bell housing. There might be some brass plugs behind the engine backplate involved with coolant, or the back of the block may be cracked, but I would expect water to pool in the bottom of the bell housing.
All of the above would result in coolant loss, so if you hardly ever have to top it up, the water has to be from another source; is it possible for rain to drip on to the motor? Otherwise, you are back to bilge or engine tray water.
If there’s too much bilge water it can get into the starter