Impeller Clearance Adjustment - Mercury 40 jet fourstroke User Manual

Check the impeller blades occasionally for damage. Use a flat
file to sharpen the leading edges. Sharpen to a 0.8 mm (1/32 in.)
radius by removing material from bottom side only.

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.).
As the blades wear, shims located in the stack outside of the
impeller can be transferred behind the impeller. This will move
the impeller further down into the tapered liner to reduce the
clearance.
Check the impeller clearance by sliding a feeler gauge through
the intake grate and measure the clearance between the impeller
edge and liner.
eng
MAINTENANCE
b
a
b
a - Leading edge
b - Top side lifting angle
29079
a
29080
95
a - Shims
b - Clearance between
impeller edge and liner