Timing Belt Installation - Mercury 25 EFI Service Manual

Timing, Synchronizing and Adjustments
7. Remove the timing belt tensioner. Do not lose the timing belt tensioner spring.
a
8. Lift the timing belt off of the cam gear and drive gear.

Timing Belt Installation

IMPORTANT: This engine utilizes an interference valve train design. Do not rotate the crankshaft or cams when the timing belt
is removed from the cam gears or crankshaft gear unless advised to do so. Failure to adhere to this caution may result in valve
and or piston damage.
1. Ensure the cam gear timing mark for cylinder number one and the cylinder head timing mark are in alignment.
2. Ensure the crankshaft drive gear timing mark and the cylinder block timing mark are in proper alignment.
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© 2016 Mercury Marine
a - Timing belt tensioner bolt
b - Timing belt tensioner spring
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a - Cylinder head timing mark
b - Cam gear timing mark
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Flywheel key
Crankshaft drive gear timing mark
Cylinder block timing mark
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90-8M0105568 eng MARCH 2016