MJM Yachts 40z Express - Manual (Page 11)

CHAPTER 3
Prevention is easy: Visually inspect cooling hoses and squeeze them to be sure they retain shape and
set.
6. CLOGGED INTAKE: Floating debris in the water is another culprit. Things like discarded plastic
baggies, weeds, etc. can plug up the raw-water intake. You can avoid this problem by visually inspecting
the strainer basket. When removing debris, be sure to properly replace the seal, otherwise the pump will
lose suction. Smearing the seal with Vaseline or other marine-grade grease helps.
7. HARD KNOCKS: Collision with an underwater obstacle that damages the propulsion system. Often
you can still operate the boat at low RPM to return to port, being careful to avoid excessive vibration that
might otherwise compound the damage by damaging the transmission. The problem may be corrected in
a day or so without hauling by an experienced diver who has access to a prop shop where the blades can
be repaired and the prop re-balanced, then re-installed.
8. BAD BATTERY: Marine starting batteries die from old age and neglect. Keep the terminals and
posts clean from that green corrosion that builds up, restricting the flow of current – preventing them from
fully charging. Periodically have your batteries tested to determine their condition and expected longevity.
The 40z is equipped with a “parallel” switch which can be turned on to employ the 400 ampere-hour
house bank in starting the engine.
9. STALE GASOLINE: Not applicable
10. SAGGING BELT: As V-belts wear, they stretch and begin to slip. Consequently, alternators and
water pumps don’t spin to their full speed. Batteries may not fully charge and coolant circulates
sluggishly. The solution is to check belt tension regularly and tighten belts when necessary. Drive belts
can also snap. The only way to avoid this malady is to replace them once they begin to show wear.
Spare belts are provided in the Yanmar spares kit
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PROPULSION SYSTEM