Water Testing - Mercury 40 JET FOURSTROKE Operation, Maintenance & Installation Manual

Description
Tilt stop pins

Water Testing

CHECKING FOR CAVITATION
The initial outboard height setting should be close to the optimum setting for the
outboard. However, because of the hull design of some boats, obstructions, or
imperfections in the hull ahead of the water intake, adjustments may be
required to prevent cavitation at running speeds.
When operating the boat, the outboard driveshaft housing should be vertical, or
tilted toward the boat, when planing to provide a scooping angle on the water
intake. Tilting the outboard out beyond a vertical position reduces the scoop
angle and can cause impeller slippage and cavitation.
IMPORTANT: If the angle of the boat transom does not allow the driveshaft
housing to be positioned vertical, a wedge kit should be installed behind the
transom brackets to increase the tilt‑in angle.
NOTE: Slight cavitation in sharp turns and rough water is acceptable, but
excessive cavitation is harmful to the outboard and should be avoided.
Test run the boat. If cavitation occurs (air enters the pump), the first thing to try
is lowering the outboard mounting height.
If cavitation still exists after lowering the outboard, it may be helpful to seek
advice from the boat manufacturer.
Another option to further reduce cavitation is a rough water plate.
OUTBOARD INSTALLATION
Nm
24.4
96
lb‑in. lb‑ft
18
eng