Cavitation; Elevation And Climate; Getting Started; 20-Hour Break-In Period - Mercury Mercruiser Tow Sport 5.7 MPI Manual

Section 3 - On The Water
• Clean, free of barnacles and marine growth
• Free of distortion; nearly flat where it contacts the water
• Straight and smooth, fore and aft
Marine vegetation may accumulate when the boat is docked. This growth must be removed before operation; it may clog the
water inlets and cause the engine to overheat.

Cavitation

Cavitation occurs when water flow cannot follow the contour of a fast‑moving underwater object, such as a gear housing or a
propeller. Cavitation increases propeller speed while reducing boat speed. Cavitation can seriously erode the surface of the
gear housing or the propeller. Common causes of cavitation are:
• Weeds or other debris snagged on the propeller
• Bent propeller blade
• Raised burrs or sharp edges on the propeller

Elevation and Climate

Elevation and climate changes will affect the performance of your power package. Loss of performance can be caused by:
• Higher elevations
• Higher temperatures
• Low barometric pressures
• High humidity
For you to have optimum engine performance under changing weather conditions, it is essential that the engine be propped to
allow the engine to operate at or near the top end of the specified maximum RPM range with a normal boat load during your
normal boating weather conditions.
In most cases, recommended RPM can be achieved by changing to a lower pitch propeller.

Getting Started

20‑Hour Break‑In Period
IMPORTANT: The first 20 hours of operation is the engine break‑in period. Correct break‑in is essential to obtain minimum oil
consumption and maximum engine performance. During this break‑in period, the following rules must be observed:
• Do not operate below 1500 RPM for extended periods of time for the first 10 hours. Shift into gear as soon as possible after
starting and advance the throttle above 1500 RPM if conditions permit safe operation.
• Do not operate at one speed consistently for extended periods.
• Do not exceed 3/4 throttle during the first 10 hours. During the next 10 hours, occasional operation at full throttle is
permissible (five minutes at a time maximum).
• Avoid full throttle acceleration from idle speed.
• Do not operate at full throttle until the engine reaches normal operating temperature.
• Frequently check engine oil level. Add oil as needed. It is normal for oil consumption to be high during the break‑in period.
After Break‑In Period
To help extend the life of your Mercury MerCruiser power package, follow these recommendations:
• Ensure that the propeller allows the engine to operate at or near the top of the specified WOT RPM range. Refer to
Specifications and Maintenance.
• Operate the engine at 3/4 throttle or lower. Refrain from prolonged operation at wide‑open throttle RPM.
• Change the engine oil and oil filter. Refer to Maintenance.
•
Change the transmission oil and filter. Refer to Maintenance (ZF Transmission models).

End of First Season Checkup

At the end of the first season of operation, contact an authorized Mercury MerCruiser dealer to discuss and/or perform
scheduled maintenance items. If you are in an area where the product is operated continuously, year‑round, you should contact
your dealer at the end of the first 100 hours of operation or once yearly, whichever occurs first.
1. Require fluid and filter change after the first 25 hours and then every 100 hours.
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90-8M0076545 NOVEMBER 2012
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