Piston Rings - Mercury FourStroke 2.5 Service Manual

Piston Rings

Piston Ring Side Clearance
Measure the piston ring side clearance and replace the piston or rings if out of specification.
Piston Ring Side Clearance (Standard)
Top
Middle
Bottom
Piston Ring Side Clearance (Service Limit)
Top
Middle
Bottom
Piston Ring End Gap Clearance
1. Push the piston ring into the bore of the cylinder with the crown of the piston to a depth of 20 mm (0.787 in.).
2. Measure piston ring end gap clearance.
3. Replace rings as a set if out of specification.
a - 20 mm (0.787 in.)
b - Feeler gauge
c - Piston ring end gap
90-8M0065421 NOVEMBER 2012
0.04–0.08 mm (0.0016–0.0031 in.)
0.03–0.07 mm (0.0012–0.00276 in.)
0.05–0.15 mm (0.002–0.0059 in.)
0.10 mm (0.0039 in.)
0.09 mm (0.0035 in.)
0.17 mm (0.0067 in.)
c
b
Powerhead
3136
a
26622
Page 4A-27