Impeller Clearance Adjustment - Mercury 25 Jet 4-Stroke Manual

MAINTENANCE
Check the impeller blades occasionally for damage. Use a flat file
to resharpen the leading edges. Sharpen to a 0.8 mm (1/32 in.)
radius by removing material from bottom side only.
b
a
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a - Leading edge b - Top side lifting angle

Impeller Clearance Adjustment

The impeller should be adjusted so there is approximately
0.8 mm (0.03 in.) clearance between the impeller edge and liner.
Operating the jet drive in waters that contain sand and gravel can
cause wear to the impeller blades, and the clearance will start to
exceed 0.8 mm (0.03 in.).
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