Cleaning And Inspection; Camshaft; Valves - Mercury 15 EFI FourStroke Service Manual

Cleaning and Inspection

Camshaft

1. Measure the cam lobe at its maximum valve lift. Replace the cam if any of the cam lobe dimensions are out of
specification.
Cam Lobe
Intake
Exhaust
2. Measure the outer diameter of the upper and lower bearing journals. Replace the cam if the journal dimensions are out of
specification.
a
Cam Bearing Journal
Lower bearing outside diameter
Upper bearing outside diameter

Valves

1. Inspect the valves for damage or warpage. Replace if necessary.
a. Measure the valve stem cylindricity. Replace the valves if out of specification.
Cylindricity (Maximum)
Intake and exhaust
2. Measure the valve stem outer diameter. Replace valves if out of specification.
90-8M0125265 eng NOVEMBER 2017
21391
23.63 mm (0.9303 in.)
23.80 mm (0.9370 in.)
a - Lower bearing outside diameter
b - Upper bearing outside diameter
b
3004
20970
20971
© 2018 Mercury Marine
15.95–15.97 mm (0.628–0.629 in.)
17.95–17.98 mm (0.707–0.708 in.)
0.01 mm (0.0004 in.)
Cylinder Head
Page 4B-15