Operating At High Elevations; Setting Trim Angle While Running Engine At Idle Speed; Engine Break-In - Mercury 150 Operation, Maintenance And Installation Manual

If you keep your boat moored in the water, always tilt the outboard so the
gearcase is completely out of water (except in freezing temperatures) when not
in use.
Wash the outboard exterior and flush out the exhaust outlet of the propeller and
gearcase with fresh water after each use. Each month, spray Mercury Precision
or Quicksilver Corrosion Guard on external metal surfaces. Do not spray on
corrosion control anodes as this will reduce the effectiveness of the anodes.

Operating at High Elevations

Your engine automatically compensates for high elevation changes. A different
pitch propeller may help reduce some normal performance loss resulting from
reduced oxygen in the air. Consult your dealer.

Setting Trim Angle While Running Engine at Idle Speed

Submerging the exhaust relief hole on the outboard can happen on some boats
if you trim full in while running at idle speed, resulting in, exhaust restriction,
rough idle, excessive smoke, and fouled spark plugs. If this condition exists,
trim outboard up until exhaust relief hole is out of the water.
a
Engine Break‑in
IMPORTANT: Failure to follow the engine break‑in procedures can result in
poor performance throughout the life of the engine and can cause engine
damage. Always follow break‑in procedures.
Vary throttle settings during break‑in. Use the following suggestions.
First Hour
• Allow the engine to warm‑up for 30–60 seconds.
• Do not idle for more than five minutes.
• Run the engine the majority of the time between 4000–5400 RPM
(approximately three‑quarter throttle).
• Short bursts of wide‑open throttle for 10 seconds or less are acceptable.
• Change the engine speed approximately every two minutes.
• Avoid trimming the outboard out (up) beyond a vertical trim position
during operation.
eng
OPERATION
b
2729
Break‑in Procedure
35
a - Relief hole submerged
(wrong)
b - Relief hole above waterline
(correct)