POWERHEAD
90-826883R2 JUNE 1998
Page 4-31
Pistons
IMPORTANT: If engine was submerged while engine was running, piston and/or
connecting rod may be bent. If piston pin is bent, piston must be replaced. If piston
pin is bent, connecting rod must be checked for straightness.
1. Inspect pistons for scoring and excessive piston skirt wear.
2. Check tightness of piston ring locating pins. Locating pins must be tight.
57105
a
a -
Locating Pins
3. Thoroughly clean pistons. Carefully remove carbon deposits from pistons, with a soft
wire brush or carbon remove solution. Do not burr or round off machined edges.
Inspect piston ring grooves for wear and carbon accumulation. If necessary, scrape car-
bon from piston ring grooves
being careful not to scratch sides of grooves
. Refer to
procedure following for cleaning piston ring grooves.
CLEANING PISTON RING GROOVES
Keystone (tapered) ring grooves
CAUTION
Care must be taken not to scratch the side surfaces of the ring groove. Scratching
the side surface of the ring groove will damage the ring groove.
1. Use a bristle brush and carbon remover solution to remove carbon from side surfaces
.
2. A tool can be made for cleaning the inner diameter of the tapered ring grooves. For
the top ring groove, a tool can be made from a broken tapered piston ring with the side
taper removed to enable the inside edge of the ring to reach the inner diameter of the
groove. For the bottom ring groove, a tool can be made from a broken rectangular ring.
Carefully scrape carbon from inner diameter of ring grooves. Care must be taken not
to damage the grooves by scratching the side surfaces of the grooves.
Piston with 1 half keystone (half tapered) and 1 rectangular ring.