Engine Alignment - Mercury MerCruiser Product Applications Manual

Engine
CYLINDER HEADS

Engine Alignment

Proper alignment between the transmission, and the propeller shaft is essential to minimize
noise, vibration, and power loss and to avoid overstressing the transmission and drive line
components. A preliminary alignment should be performed at the time of installing the
engine. The final alignment must be done after the boat is in the water to compensate for
any deflection in the hull. On applications with a rigid propeller shaft coupler, the coupler
should be disconnected from the transmission for shipment. The alignment should then be
rechecked with the boat in the water. The requirement for checking the alignment should
be clearly communicated to your dealers, along with an understanding as to who is
financially responsible.
The complete alignment procedure is outlined in the installation manuals. Important
elements of this process include:
• Align the engine to position the pilot on the propeller shaft coupler into the recess in
the transmission output flange so that the mating surfaces of the flange and the coupler
are parallel within 0.07 mm (0.003 in.).
Page 3A-18
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Typical cylinder head
6338
7534
90-863758060 AUGUST 2006