Setting Trim Angle While Running Engine At Idle Speed; Engine Break-In Procedure - Mercury 135 Verado FourStroke Operation And Maintenance Manual

EXAMPLE: An engine running at an elevation of 8,000 feet will have over a
30% power loss while a loss of engine power on a hot and humid day could be
as much as 14%. These losses apply to normally aspirated and supercharged
engines.
Compensating for power robbing conditions:
• Switch to lower pitch propeller.
• Change gear ratio.
Some boat performance can be improved by dropping to a lower pitch
propeller, but engine performance will still remain lower. In some cases, a gear
ratio reduction may be more beneficial. To optimize engine performance, prop
the engine to allow it to operate at or near the top end of the recommended
maximum RPM range at wide‑open throttle with a normal boat load.
Other advantages to propeller or gear ratio changes:
• Reduces the possibility of detonation
• Enhances overall reliability and durability of the engine

Setting Trim Angle While Running Engine at Idle Speed

The exhaust relief hole on the outboard can become submerged on some
boats if the engine is trimmed full in while running at idle speed. This may result
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 Procedure
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.
1. For the first two hours of operation, run the engine at varied throttle
settings up to 4500 RPM or at three‑quarter throttle, and at full throttle for
approximately one minute every ten minutes.
2. For the next eight hours of operation, avoid continuous operation at full
throttle for more than five minutes at a time.
OPERATION
b
2729
54
a - Relief hole submerged
(wrong)
b - Relief hole above water
line (correct)
eng