Dodge ram truck 3500 1996 Service Manual page 1051

DESCRIPTION AND
O P E R A T I O N ( C o n t i n u e d !
ENGINE COMPONENTS
CYLINDER
HEAD
The alloy cast iron cylinder heads (Fig. 5) are held
in place by 1 0 bolts. The spark plugs are located in
the peak of the wedge between the valves.
The 5.2L cylinder head is identified by the foundry
mark NH.
EXHAUST SPARK EXHAUST SPARK EXHAUST
VALVE PLUGS VALVES PLUGS VALVE
INTAKE INTAKE
VALVES VALVES J9309-37
Fig. 5 Cylinder Head Assembly
PISTONS
All pistons are machined to the same weight,
regardless of size, to maintain piston balance.
The pistons are elliptically turned so that the
diameter at the pin boss is less than its diameter
across the thrust face. This allows for expansion
under normal operating conditions. Under operating
temperatures, expansion forces the pin bosses away
from each other, causing the piston to assume a more
nearly round shape.
The piston pin rotates i n the piston only and is
retained by the press interference fit of the piston
pin in the connecting rod.
SERVICE P R O C E D U R E S
VALVE THING
( 1 ) Turn crankshaft until the No.6 exhaust valve is
closing and No.6 intake valve is opening.
(2) Insert a 6.350 mm (1/4 inch) spacer between
rocker arm pad and stem tip of No.l intake valve.
Allow spring load to bleed tappet down giving in
effect a solid tappet.
(3) Install a dial indicator so plunger contacts
valve spring retainer as nearly perpendicular as pos­
sible. Zero the indicator.
(4) Rotate the crankshaft clockwise (normal run­
ning direction) until the valve has lifted 0.863 mm
(0.034 inch). The timing of the crankshaft should
now read from 10° before top dead center to 2° after
top dead center. Remove spacer.
CAUTION: DO NOT turn crankshaft any further
clockwise as valve spring might bottom and result
in serious damage.
I f reading is not within specified limits:
• Check sprocket index marks.
• Inspect timing chain for wear.
• Check accuracy of DC mark on timing indicator.
MEASURING TIMING CHAIN STRETCH
NOTE: To access timing chain Refer to Timing
Chain Cover in Removal and Installation Section.
(1) Place a scale next to the timing chain so that
any movement of the chain may be measured.
(2) Place a torque wrench and socket over cam­
shaft sprocket attaching bolt. Apply torque i n the
direction of crankshaft rotation to take up slack; 41
N-m (30 ft. lbs.) torque with cylinder head installed
or 20 N-m (15 ft. lbs.) torque with cylinder head
removed. With a torque applied to the camshaft
sprocket bolt, crankshaft should not be permitted to
move. I t may be necessary to block the crankshaft to
prevent rotation.
(3) Hold a scale with dimensional reading even
with the edge of a chain link. With cylinder heads
installed, apply 14 N-m (30 ft. lbs.) torque in the
reverse direction. With the cylinder heads removed,
apply 20 N-m (15 ft. lbs.) torque in the reverse direc­
tion. Note the amount of chain movement (Fig. 6).
Fig. 6 Measuring Timing Chain Wear and Stretch
(4) Install a new timing chain, i f its movement
exceeds 3.175 mm (1/8 inch).
(5) I f chain is not satisfactory, remove camshaft
sprocket attaching bolt and remove timing chain with
crankshaft and camshaft sprockets.
(6) Place both camshaft sprocket and crankshaft
sprocket on the bench with timing marks on exact
imaginary center line through both camshaft and
crankshaft bores.
(7) Place timing chain around both sprockets.