Dodge ram truck 3500 1996 Service Manual page 1121

B R
8.0L ENGINE 9 - 1 3 1
S E R V I C E P R O C E D U R E S (Continued)
(4) Install a new timing chain, i f its movement
exceeds 3.175 mm (1/8 inch).
FITTING PISTONS
Piston and cylinder wall must be clean and dry.
Specified clearance between the piston and the cylin­
der wall is 0.013-0.038 mm (0.0005-0.0015 inch).
Piston diameter should be measured at the top- of
skirt, 90° to piston pin axis. Cylinder bores should be
measured halfway down the cylinder bore and trans­
verse to the engine crankshaft center line.
Pistons and cylinder bores should be measured at
normal room temperature, 21°C (70°F).
(1) To correctly select the proper size piston, a cyl­
inder bore gauge, capable of reading in .0001"
INCREMENTS is required (Fig. 7). I f a bore gauge is
not available, do not use an inside micrometer.
(2) The coating material is applied to the piston
after the final piston machining process. Measuring
the outside diameter of a coated piston will not pro­
vide accurate results. Therefore measuring the inside
diameter of the cylinder bore with a dial Bore Gauge
is MANDATORY.. To correctly select the proper size
piston, a cylinder bore gauge capable of reading in
.0001" increments is required.
(3) Piston installation into the cylinder bore require
slightly more pressure than that required for non-coated
pistons. The bonded coating on the piston will give the
appearance of a line-to-line fit with the cylinder bore.
CYLINDER
BORE
J 9 5 0 9 - 1 2 5
Fig. 7 Bore Gauge
FITTING RINGS
(1) Measurement of end gaps:
(a) Measure piston ring gap 2 inches from bot­
tom of cylinder bore. An inverted piston can be
used to push the rings down to ensure positioning
rings squarely in the cylinder bore before measur­
ing.
(b) Insert feeler stock in the gap. Gap for com­
pression rings should be between 0.254-0.508 mm
(0.010-0.020 inch). The oil ring gap should be
0.381-1.397 mm (0.015-0.055 inch).
(c) Rings with insufficient end gap may be prop­
erly filed to the correct dimension. Ends should be
stoned smooth after filing with Arkansas White
Stone. Rings with excess gaps should not be used.
(2) Install rings and confirm ring side clearance:
(a) Install oil rings being careful not to nick or
scratch the piston. Install the oil control rings
according to instructions in the package. I t is not
necessary to use a tool to install the upper and
lower rails. Insert oil rail spacer first, then side
rails.
(b) Install the second compression rings using
Installation Tool C-4184. The compression rings
must be installed with the identification mark face
up (toward top of piston) and chamfer facing down.
An identification mark on the ring is a drill point,
a stamped letter O, an oval depression or the word
TOP
(Fig. 8) (Fig. 10).
(c) Using a ring installer, install the top com­
pression ring with the chamfer facing up (Fig. 10).
An identification mark on the ring is a drill point,
a stamped letter O, an oval depression or the word
TOP facing up.
(d) Measure side clearance between piston ring
and ring land. Clearance should be 0.074-0.097 mm
(0.0029-0.0038 inch) for the compression rings. The
steel rail oil ring should be free in groove, but
should not exceed 0.246 mm (0.0097 inch) side
clearance.
(e) Pistons with insufficient or excessive side
clearance should be replaced.
SECOND COMPRESSION RING
(BLACK CAST IRON)
CHAMFER
T W O
DOTS
J9009-46
Fig. 8 Second Compression Ring Identification—Typical
(3) Arrange ring gaps 180° apart as shown in (Fig.
11).