Checking The Pistons; Checking Piston Rings - Westerbeke 9.0 BCG Technical Manual

Checking the Pistons
1. Check all pistons carefully, and replace those that exhibit severe burns or scratches on the external cir-
cumference of the piston are found.
2. Measure each piston's diameter 0.7087 inches (18 mm) under the oil ring groove, at right angles to the
piston pin's location (that is, in the thrust direction) without the pin in place.
3. Check the clearance between the piston and the cylinder wall.
Piston Diameter (Dimension A):
Standard Cylinder-to-Piston Clearance:
BCG 4.0KW 2.8167 - 2.8179 inches
(71.545 - 71.575 mm)
BCG 6.5KW and BTG 9.0KW
2.9903 - 2.9915 inches
(75.955 - 75.985 mm)
BCG 4.0KW 0.0018 - 0.0026 inches
(0.045 - 0.065 mm)
BCG 6.5KW and BTG 9.0KW
0.0014 - 0.0022 inches
(0.035 - 0.055 mm)
Allowable Cylinder-to-Piston Limit: (all Models) 0.0039 inches (0.10 mm)
18mm
(0.7087
Ill)
Checking Piston Rings
1. Check the piston rings for cracks, burning or
wear and replace, if necessary.
2. Measure each piston ring's end gap. Replace
the ring if the gap exceeds the allowable end
gap limit.
NOTE: Push a ring into the cylinder with a
piston until it is about 2 inches from the
block's top surface.
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Westerbeke Generators