Getting Started; 20-Hour Break-In Period; After Break-In Period - MerCruiser 350 MAG Owner's Manual

If full‑throttle operation is below the recommended range, the propeller must be changed
to prevent loss of performance and possible engine damage. On the other hand, operating
an engine above the recommended operating RPM range will cause higher than normal
wear and damage.
After initial propeller selection, the following common problems may require that the
propeller be changed to a lower pitch.
• Warmer weather and greater humidity cause a loss of RPM.
• Operating in a higher elevation causes a loss of RPM.
• Operating with a dirty boat bottom causes a loss of RPM.
• Operating with increased load (additional passengers, pulling skiers) causes a loss of
RPM.
For better acceleration, such as is needed for water skiing, use the next lower pitch
propeller. When not pulling skiers, do not operate at full throttle when using the 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 (5 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, the following
recommendations should be considered;
• Ensure that propeller allows the engine to operate at or near the top of the specified
WOT RPM range (Refer to Specifications and Maintenance) when at full throttle with
a normal boat load.
• Operation at 3/4 throttle setting or lower is recommended. Refrain from prolonged
operation at WOT RPM.
• Change the engine oil and oil filter. Refer to Maintenance.
• Change the transmission oil and filter. Refer to Maintenance (ZF Transmission
models).
1. Require fluid and filter change after the first 25 hours and then every 100 hours.
90-864195072 OCTOBER 2007
1.
Section 3 - On The Water
Page 47