V8 Engine 3.5 3.9 4.2
ENGINE
36
OVERHAUL
Piston rings - remove
1. Using a suitable piston ring expander, remove
and discard piston rings.
2. Remove carbon from piston ring grooves.
NOTE: Use an old broken piston ring with
a squared off end.
CAUTION: Do not use a wire brush.
Piston rings - inspection
1. Temporarily fit new compression rings to
piston.
NOTE: The ring marked ’TOP’ must be
fitted, with marking uppermost, into
second groove. The chrome ring fits into
top groove and can be fitted either way round.
2. Check compression ring to groove clearance:
Top compression ring A = 0.05 to 0.10 mm
(0.002 to 0.004 in)
2nd compression ring B = 0.05 to 0.10 mm
(0.002 to 0.004 in)
3. Insert piston ring into its relevant cylinder bore,
held square to bore with piston and check ring
gaps.
Top compression ring = 0.30 to 0.50 mm
(0.012 to 0.02 in)
2nd compression ring = 0.40 to 0.65 mm(0.016
to 0.26 in)
Oil control ring rails = 0.38 to 1.40 mm (0.14 to
0.05 in)
CAUTION: Ensure that on completion of
checking, piston rings are identified and
retained with the cylinder in which they
were checked.
