1996 CHRYSLER VOYAGER Service Manual

aligning yokes. The yokes are secured by an align-
ment yoke retainer (Fig. 4).
PRELIMINARY STEP TO CHECKING THE
HYDRAULIC TAPPETS
Before disassembling any part of the engine to cor-
rect tappet noise, read the oil pressure at the gauge.
Install a reliable gauge at pressure sending unit if
vehicle has no oil pressure gauge and check the oil
level in the oil pan. The pressure should be between
30 and 80 psi (206.8 to 551.6 kPa) at 2000 rpm.
The oil level in the pan should never be above the
MAX mark on dipstick, or below the MIN mark.
Either of these two conditions could be responsible
for noisy tappets.Oil Level Check: stop engineafter reaching normal operating temperature.
Allow 5 minutes to stabilize oil level, check dipstick.
OIL LEVEL TOO HIGH
If oil level is above the MAX mark on dip stick, it
is possible for the connecting rods to dip into the oil
while engine is running and create foam. Foam in oil
pan would be fed to the hydraulic tappets by the oil
pump causing them to become soft and allow valves
to seat noisily.
OIL LEVEL TOO LOW
Low oil level may allow pump to take in air which
when fed to the tappets, causes them to become soft
and allows valves to seat noisily. Any leaks on intake
side of pump through which air can be drawn will
create the same tappet action. Check the lubrication
system from the intake strainer to the pump cover,
including the relief valve retainer cap. When tappet
noise is due to aeration, it may be intermittent or
constant, and usually more than one tappet will be
noisy. When oil level and leaks have been corrected,
engine should be operated at fast idle to allow all of
the air inside of the tappets to be bled out.
VALVE TRAIN NOISE DIAGNOSIS
To determine source of valve train noise, operate
engine at idle with cylinder head covers removed and
listen for source of the noise.
Fig. 3 3.3/3.8L V-6 Engines
Fig. 4 Roller Tappets Aligning Yoke and Retainer
NS3.3/3.8L ENGINE 9 - 95
DIAGNOSIS AND TESTING (Continued)

NOTE: Worn valve guides or cocked springs are
sometimes mistaken for noisy tappets. If such is
the case, noise may be dampened by applying side
thrust on the valve spring. If noise is not apprecia-
bly reduced, it can be assumed the noise is in the
tappet. Inspect the rocker arm push rod sockets
and push rod ends for wear.
Valve tappet noise ranges from light noise to a
heavy click. A light noise is usually caused by exces-
sive leak-down around the unit plunger which will
necessitate replacing the tappet, or by the plunger
partially sticking in the tappet body cylinder. A heavy
click is caused either by a tappet check valve not
seating, or by foreign particles becoming wedged
between the plunger and the tappet body causing the
plunger to stick in the down position. This heavy
click will be accompanied by excessive clearance
between the valve stem and rocker arm as valve
closes. In either case, tappet assembly should be
removed for inspection and cleaning.
CHECKING ENGINE OIL PRESSURE
Check oil pressure using gauge at oil pressure
switch location. Oil pressure should be 34.47 kPa (5
psi.) at idle or 205 to 551 kPa (30 to 80 psi.) at 3000
RPM.
(1) Remove pressure sending unit and install oil
pressure gauge (Fig. 5).
CAUTION: If oil pressure is 0 at idle, do not run
engine at 3000 RPM.
(2) Warm engine at high idle until thermostat
opens.
SERVICE PROCEDURES
VALVE TIMING
(1) Remove front cylinder head cover and all 6
spark plugs.
(2) Rotate engine until the #2 piston is at TDC of
the compression stroke.
(3) Install a degree wheel on the crankshaft pulley.
(4) With proper adaptor, install a dial indicator
into #2 spark plug hole. Using the indicator find TDC
on the compression stroke.
(5) Position the degree wheel to zero.
(6) Remove dial indicator from spark plug hole.
(7) Place a 5.08 mm (0.200 in.) spacer between the
valve stem tip of #2 intake valve and rocker arm pad.
Allow tappet to bleed down to give a solid tappet
effect.
(8) Install a dial indicator so plunger contacts the
#2 intake valve spring retainer as nearly perpendic-
ular as possible. Zero the indicator.
(9) Rotate the engine clockwise until the intake
valve has lifted .254 mm (0.010 in.).
CAUTION: Do not turn crankshaft any further
clockwise as intake valve might bottom and result
in serious damage.
(10) Degree wheel should read 6 degrees BTDC to
6 degrees ATDC.
MEASURING TIMING CHAIN FOR STRETCH
(1) Place a scale next to timing chain so that any
movement of chain may be measured.
(2) Place a torque wrench and socket on camshaft
sprocket attaching bolt and apply torque in direction
of crankshaft rotation to take up slack; 41 N´m (30 ft.
lb.) with cylinder head installed or 20 N´m (15 ft. lb.)
with cylinder heads removed.With a torque
applied to the camshaft sprocket bolt, crank-
shaft should not be permitted to move. It may
be necessary to block crankshaft to prevent
rotation.
(3) Holding a scale even, with dimension reading
as shown (Fig. 6), along edge of chain links. Apply
torque in the reverse direction to 41 N´m (30 ft. lbs.)
with cylinder heads installed, or 20 N´m (15 ft. lbs.)
with cylinder heads removed. Check amount of chain
movement.
(4) Install a new timing chain, if its movement
exceeds 3.175 mm (1/8 inch).
(5) If chain is not satisfactory, refer to Timing
Chain Removal and Installation in this section.
Fig. 5 Checking Oil Pump Pressure
9 - 96 3.3/3.8L ENGINENS
DIAGNOSIS AND TESTING (Continued)

FITTING PISTONS AND RINGS
FITTING PISTONS
The piston and cylinder wall must be clean and
dry. Piston diameter should be measured 90 degrees
to piston pin at size location shown in (Fig. 8). Cyl-
inder bores should be measured halfway down the
cylinder bore and transverse to the engine crankshaft
center line shown in (Fig. 7). Refer to Cylinder Bore
and Piston Specification Chart.Pistons and cylin-
der bores should be measured at normal room
temperature, 70ÉF (21ÉC).
FITTING RINGS
(1) Wipe cylinder bore clean. Insert ring and push
down with piston to ensure it is square in bore. Thering gap measurement must be made with the ring
positioning at least 12 mm (0.50 in.) from bottom of
cylinder bore. Check gap with feeler gauge (Fig. 9).
Refer to Piston Ring Specification Chart.
(2) Check piston ring to groove clearance: (Fig. 10).
Refer to Piston Ring Specification Chart.
FITTING CONNECTING ROD BEARINGS
Fit all rods on one bank until complete.
The bearing caps are not interchangeable and
should be marked at removal to insure correct
assembly.
The bearing shells must be installed with the
tangs inserted into the machined grooves in the rods
and caps. Install cap with the tangs on the same side
as the rod.
Limits of taper or out-of-round on any crankshaft
journals should be held to 0.025 mm (0.001 in.).
Bearings are available in 0.025 mm (0.001 in.) and
0.250 mm (0.010 in.) undersize.Install the bear-
ings in pairs. Do not use a new bearing half
Fig. 6 Measuring Timing Chain Wear and Stretch
Fig. 7 Checking Cylinder Bore Size
CYLINDER BORE AND PISTON
SPECIFICATION CHART
EngineStandard
BoreMaximum
Out-Of-
RoundMaximum
Taper
3.3L 92.993 -
93.007 mm0.076 mm 0.51 mm
(3.661 -
3.6617 in.)(0.003 in.) (0.002 in.)
3.8L 95.993 -
96.007 mmSame Same
3.7792 -
3.780 in.
Standard Piston Size
3.3L 92.950 - 92.968 mm (3.6594 - 3.6602 in.)
3.8L 95.950 - 95.968 mm (3.7776 - 3.7783 in.)
Piston to Bore Clearance: 0.025 - 0.057 mm
(0.0009 - 0.0022 in.)
Measurements taken at Piston Size Location.
Fig. 8 Piston Measurements
NS3.3/3.8L ENGINE 9 - 97
SERVICE PROCEDURES (Continued)