1993 DODGE TRUCK Service Repair Manual

TRANSFER

CASE

INSULATOR

MOUNTING PLATE

NUT(B
RAIL

ASSEMBLY
SPACER

UPPER

INSULATOR

NUT®
LOWER

INSULATOR

J9109-242
Fig.
9 Rear
Engine
Support—4WD
with
Manual

Transmission
(8) If necessary, remove the transmission support
spacer (automatic transmission) from the extension
assembly (Fig. 8).
(9) If necessary, remove the engine rear support
plate (automatic transmission) from the transfer case (Fig. 8).

INSTALLATION-4WD
(1) If removed, position the engine rear support
plate (automatic transmission) to the transfer case (Fig. 8). Install the bolts and tighten to 41 N-m (30
ft. lbs.) torque.
(2) If removed, position the transmission support
spacer (automatic transmission) to the extension as­
sembly (Fig. 8). Install the bolts and tighten to 68 N-m (50 ft. lbs.) torque.
(3) Install insulator mounting plate, mounting

bolts,
spacers, washers and upper/lower insulators to
the rail assembly (Figs. 8 and 9). Tighten the mount­
ing nuts to 204 N*m (150 ft. lbs.) torque.
(4) AUTOMATIC TRANSMISSION-Align the
engine rear support plate and the transmission sup­
port spacer to the insulator mounting plate (Fig. 8). Lower the engine and transmission onto the insula­
tor mounting plate and install the bolts. Tighten the transmission support spacer nuts to 204 N-m (150 ft. lbs.) torque. Tighten the engine rear support plate
bolts to 41 N-m (30 ft. lbs.) torque.
(5) MANUAL TRANSMISSION—Align the
transfer case to the insulator mounting plate and lower the engine and transmission. Install the bolts and tighten the nuts (Fig. 9 - nut A) to 204 N-m (150 ft. lbs.) torque. Install the bolts and tighten the nuts
(Fig. 9 - nut B) to 41 N-m (30 ft. lbs.) torque. (6) Install the skid plate.
(7) Lower the vehicle.

ENGINE
ASSEMBLY

REMOVAL (1) Scribe hood hinge outlines on hood. Remove the
hood.
(2) Remove the battery. (3) Drain cooling system (refer to Group 7, Cooling
System for the proper procedure).
(4) Remove the air cleaner. (5) Disconnect the radiator and heater hoses. Re­
move radiator (refer to Group 7, Cooling System).
(6) Set fan shroud aside. (7) Remove the vacuum lines. (8) Remove the distributor cap and wiring.
(9) Disconnect the accelerator linkage.
(10) Remove MPI throttle body. (11) Disconnect the fuel lines. (12) Disconnect the starter wires.
(13) Disconnect the oil pressure wire. (14) Discharge the air conditioning system, if
equipped (refer to Group 24, Heating and Air Condi­
tioning for service procedures). (15) Disconnect the air conditioning hoses.
(16) Disconnect the power steering hoses, if
equipped. (17) Remove starter motor (refer to Group 8B, Bat­
tery/Starter/Generator Service). (18) Remove the generator (refer to Group 8B, Bat­
tery/Starter/Generator Service).
(19) Raise and support the vehicle on a hoist.
(20) Disconnect exhaust pipe at manifold.
(21) AUTOMATIC TRANSMISSION: (a) Support transmission. This will assure that
the torque converter will remain in proper position in the transmission housing. (b) Remove bell housing bolts and inspection
plate.
(c) Attach a C-clamp on front bottom of trans­
mission torque converter housing to prevent torque
converter from falling out.
(d) Remove torque converter drive plate bolts
from torque converter drive plate. Mark converter and drive plate to aid in assembly.
(22) MANUAL TRANSMISSION: (a) Support transmission.
(b) Disconnect clutch release mechanism and re­
move transmission to clutch housing bolts.

CAUTION:
DO NOT
lift
the engine by the intake
manifold.

(23) Install an engine lifting fixture.
(24) Remove engine front mount bolts.

•
3.9L
ENGINE
9 - 21 (25) Lower the vehicle.
(26) On automatic transmission vehicles, discon­
nect the engine from the torque converter drive
plate. On manual transmission vehicles, move engine forward until drive pinion shaft clears the clutch

disc.
Remove engine from engine compartment. (27) Install engine assembly on engine repair
stand.
INSTALLATION (1) Remove engine from the repair stand and posi­
tion in the engine compartment.
(2) Install engine support fixture.
(3) Raise and support the vehicle on a hoist.

(4)
AUTOMATIC TRANSMISSION: (a) Position the torque converter and drive plate.
Install torque converter drive plate bolts. Tighten
the bolts to 31 Nnn (270 in. lbs.) torque.
(b) Install the engine front mounts.
(c) Install bell housing bolts. Tighten the bolts to
41 N-m (30 ft. lbs.) torque.
(d) Remove C-clamp.
(e) Install the inspection plate.
(5) MANUAL TRANSMISSION: (a) Position the drive pinion shaft to the clutch

disc.
(b) Connect the clutch release mechanism and
install the transmission to clutch bolts. Tighten the
bolts to 68 N-m (50 ft. lbs.) torque.
(c) Install the engine front mounts.
(6) Remove transmission support.
(7) Install exhaust pipe to manifold.
(8) Lower the vehicle.
(9) Remove engine lifting fixture.
(10) Install the generator (refer to Group 8B, Bat­
tery/Starter/Generator Service). (11) Install starter motor (refer to Group 8B, Bat­
tery/Starter/Generator Service). (12) Connect power steering hoses, if equipped.
(13) Connect air conditioning hoses.
(14) Evacuate and charge the air conditioning sys­
tem, if equipped (refer to Group 24, Heater and Air Conditioning for service procedures). (15) Using a new gasket, install MPI throttle body.
Tighten the throttle body bolts to 23 N-m (200 in. lbs.) torque. (16) Connect the accelerator linkage.
(17) Connect the starter wires. (18) Connect the oil pressure wire.
(19) Install the distributor cap and wiring.
(20) Connect the vacuum lines.
(21) Connect the fuel lines.
(22) Install the radiator (refer to Group 7, Cooling
System). Connect the radiator hoses and heater

hoses.

(23) Install fan shroud in position. (24) Fill cooling system (refer to Group 7, Cooling
System for the proper procedures). (25) Install the air cleaner.
(26) Install the battery.
(27) Warm engine and adjust.
(28) Install hood and line up with the scribe
marks. (29) Road test vehicle.

CYLINDER
HEAD COVER
A steel backed silicon gasket is used with the cyl­
inder head cover (Fig. 1). This gasket can be used again.

CYLINDER HEAD COVER GASKET

J9209-104

Fig.
1 Cylinder Head
Cover
Gasket

REMOVAL (1) Disconnect the negative cable from the battery.
(2) Disconnect closed ventilation system and evap­
oration control system from cylinder head cover. (3) Remove cylinder head cover and gasket. The
gasket may be used again.
CLEANING Clean cylinder head cover gasket surface. Clean head rail, if necessary.
INSPECTION Inspect cover for distortion and straighten, if nec­
essary. Check the gasket for use in "head cover installation.
If damaged, use a new gasket.
INSTALLATION (1) The cylinder head cover gasket can be used
again. Install the gasket onto the head rail.
(2) Position the cylinder head cover onto the gas­
ket. Tighten the bolts to 11 N-m (95 in. lbs.) torque. (3) Install closed crankcase ventilation system and
evaporation control system.
(4) Connect the negative cable to the battery.

ROCKER
ARMS

REMOVAL (1) Disconnect spark plug wires by pulling on the
boot straight out in line with plug.
(2) Remove cylinder head cover and gasket.

(3) Remove the rocker arm bolts and pivots (Fig.

2).
Place them on a bench in the same order as re­
moved.
(4) Remove the push rods and place them on a
bench in the same order as removed.

ROCKER
ARMS

J9209-66
Fig.
2
Rocker Arms
INSTALLATION
(1) Rotate the crankshaft until the "V6" mark
lines up with the TDC mark on the timing chain
case cover. This mark is located 147° ATDC from the
No.l firing position.

CAUTION:
DO NOT
rotate
or
crank
the
engine dur­
ing
or
immediately
after
rocker
arm
installation.
Al­

low
the
hydraulic roller tappets adequate time
to
bleed down (about
5
minutes).

(2) Install the push rods in the same order as re­
moved.
(3) Install rocker arm and pivot assemblies in the
same order as removed. Tighten the rocker arm bolts
to 28 N*m (21 ft. lbs.) torque.
(4) Install cylinder head cover.
(5) Connect spark plug wires.

CYLINDER
HEADS
The alloy cast iron cylinder heads (Fig. 3) are held
in place by 8 bolts. The spark plugs are located in
the peak of the wedge between the valves.

REMOVAL
(1) Disconnect the negative cable from the battery.
(2) Drain cooling system (refer to Group 7, Cooling
System for the proper procedures). (3) Remove the heat shields (Fig. 4).
SPARK SPARK
INTAKE

PLUGS
PLUG VALVE
EXHAUST INTAKE EXHAUST VALVE VALVES VALVES
J9309-35

Fig.
3 Cylinder Head
Assembly Fig.
4
Exhaust
Manifold Heat
Shields

(4) Remove the intake manifold-to-generator
bracket support rod. Remove the generator.
(5) Remove closed crankcase ventilation system.
(6) Disconnect the evaporation control system.
(7) Remove the air cleaner.
(8) Disconnect the fuel lines.
(9) Disconnect accelerator linkage and if so
equipped, the speed control and transmission kick-
down cables. (10) Remove the return spring.
(11) Remove distributor cap and wires.
(12) Disconnect the coil wires.
(13) Disconnect heat indicator sending unit wire.
(14) Disconnect heater hoses and bypass hose.
(15) Remove cylinder head covers and gaskets.
(16) Remove intake manifold and throttle body as
an assembly. Discard the flange side gaskets and the
front and rear cross-over gaskets.
(17) Remove exhaust manifolds.
(18) Remove rocker arm assemblies and push rods.
Identify to ensure installation in original locations.

•
3.9L
ENGINE
9 - 23 (19) Remove the head bolts from each cylinder
head and remove cylinder heads. Discard the cylin­ der head gasket.
(20) Remove spark plugs.

CLEANING
Clean all surfaces of cylinder block and cylinder

heads.
Clean cylinder block front and rear gasket surfaces
using a suitable solvent.

INSPECTION
Inspect all surfaces with a straightedge if there is
any reason to suspect leakage. If out-of-flatness ex­
ceeds 0.00075 mm/mm (0.00075 inch/inch) times the
span length in any direction, either replace head or
lightly machine the head surface.
FOR EXAMPLE:—A 305 mm (12 inch) span is
0.102 mm (0.004 inch) out-of-flat. The allowable out-
of-flat is 305 x 0,00075 (12 x 0.00075) equals 0.23
mm (0.009 inch). This amount of out-of-flat is accept­
able.

The cylinder head surface finish should be 1.78-
3.00 microns (70-125 microinches). Inspect push rods. Replace worn or bent rods.

INSTALLATION
(1) Apply Perfect Sealant No.5, or equivalent, to
both sides of the gasket (Fig. 5).

PERFECT
SEALANT
NO.
5
PERFECT
SEALANT
NO.
5

Fig.
5 Sealant Location on Cylinder Head
Gasket

(2) Position the new cylinder head gaskets onto the
cylinder block.
(3) Position the cylinder heads onto head gaskets
and cylinder block.
(4) Starting at top center, tighten all cylinder head

bolts,
in sequence, to 68 N»m (50 ft. lbs.) torque (Fig.
6).
Repeat procedure, tighten all cylinder head bolts
to 143 N»m (105 ft. lbs.) torque. Repeat procedure to
confirm that all bolts are at 143 N*m (105 ft. lbs.)
torque.

CAUTION:
When
tightening the rocker arm
bolts,
Fig.
6 Cylinder Head
Bolt
Tightening
Sequence

make
sure
the
piston
in
that
cylinder is NOT at

TDC.
Contact
between the
valves
and
piston
could
occur.

(5) Install push rods and rocker arm assemblies in
their original position. Tighten the bolts to 28 Nnn (21 ft. lbs.) torque.
(6) Place the 4 plastic locator dowels into the holes
in the block Fig. 7). (7) Apply Mopar Silicone Rubber Adhesive Seal­
ant, or equivalent, to the four corner joints. An ex­
cessive amount of sealant is not required to ensure a
leak proof seal. However, an excessive amount of sealant may reduce the effectiveness of the flange
gasket. The sealant should be slightly higher than
the cross-over gaskets, approx. 5 mm (0.2 in).
(8) Install the front and rear cross-over gaskets
onto the dowels (Fig. 7).
FRONT
CROSS-OVER
GASKET

REAR
CROSS-OVER
GASKET
J9209-99

Fig.
7
Cross-Over
Gaskets
and Locator
Dowels

(9) Install the flange gaskets. Be sure that the ver­
tical port alignment tab is resting on the deck face of
the block. Also the horizontal alignment tabs must
be in position with the mating cylinder head gasket
tabs (Fig. 8). The words MANIFOLD SIDE should be
visible on the center of each flange gasket.
FLANGE GASKET


INTAKE
AAANIFOLD
CYLINDER
HEAD GASKET
J9209-101

Fig.
8 Intake Manifold Flange
Gasket
Alignment

(10) Carefully lower intake manifold into position
on the cylinder block and cylinder heads. Use the alignment dowels in the cross-over gaskets to posi­
tion the intake manifold. After intake manifold is in
place, inspect to make sure seals are in place.
(11) The following torque sequence duplicates the
expected results of the automated assembly system
(Fig. 9).
• Step
1-Tighten
bolts 1 and 2 to 8 N-m (72 in. lbs.)
torque. Tighten in alternating steps 1.4 N-m (12 in. lbs.) torque at a time.
• Step 2—Tighten bolts 3 through 12, in sequence,
to 8 N-m (72 in. lbs.) torque.
• Step 3—Check that all bolts are tighten to 8 N-m (72 in. lbs.) torque.
• Step 4—Tighten all bolts, in sequence, to 16 N-m (12 ft. lbs.) torque.
• Step 5—Check that all bolts are tighten to 16 N-m (12 ft. lbs.) torque. (12) Install exhaust manifolds. Tighten the bolts
and nuts to 34 N-m (25 ft. lbs.) torque.
FRONT OF ENGINE

J9209-59

Fig.
9 Intake Manifold
Bolt
Tightening
Sequence
(13) Adjust spark plugs to specifications (refer to
Group 8D, Ignition System). Install the plugs and
tighten to 41 N-m (30 ft. lbs.) torque.
(14) Install coil wires. (15) Connect heat indicator sending unit wire.
(16) Connect the heater hoses and bypass hose.
(17) Install distributor cap and wires.
(18) Hook up the return spring.
(19) Connect the accelerator linkage and if so
equipped, the speed control and transmission kick-
down cables.
(20) Install the fuel lines.
(21) Install the generator and drive belt. Tighten
generator mounting bolt to 41 N-m (30 ft. lbs.)
torque. Tighten the adjusting strap bolt to 23 N-m (200 in. lbs.) torque. Refer to Group 7, Cooling Sys­
tem for adjusting the belt tension. (22) Install the intake manifold-to-generator
bracket support rod. Tighten the bolts. (23) Place the cylinder head cover gaskets in posi­
tion and install cylinder head covers. Tighten the
bolts to 11 N-m (95 in. lbs.) torque.
(24) Install closed crankcase ventilation system.
(25) Connect the evaporation control system.
(26) Install the air cleaner.
(27) Install the heat shields. Tighten the bolts to
41 N-m (30 ft. lbs.) torque. (28) Fill cooling system (refer to Group 7, Cooling
System for proper procedure). (29) Connect the negative cable to the battery.

•

3.9L
ENGINE
9 - 25
VALVES
/
VALVE
SPRINGS

The valves are arranged in-line and inclined 18°.
The rocker pivot support and the valve guides are cast integral with the heads. This procedure requires the removal of the cylinder
head.

REMOVAL
(1) Remove the cylinder head.
(2) Compress valve springs using Valve Spring
Compressor Tool MD-998772A.
(3) Remove valve retaining locks, valve spring re­
tainers, valve stem seals and valve springs.
(4) Before removing valves, remove any burrs from
valve stem lock grooves to prevent damage to the
valve guides. Identify valves to ensure installation in
original location.

VALVE
CLEANING
Clean valves thoroughly. Discard burned, warped
and cracked valves.
Remove carbon and varnish deposits from inside of
valve guides with a reliable guide cleaner.
VALVE
INSPECTION
Measure valve stems for wear. If wear exceeds
0.051 mm (0.002 inch), replace the valve. Measure valve stem guide clearance as follows:
(a) Install Valve Guide Sleeve Tool C-3973 over
valve stem and install valve (Fig. 10). The special sleeve places the valve at the correct height for
checking with a dial indicator.

Fig.
10 Positioning Valve with Tool C-3973
(b) Attach dial indicator Tool C-3339 to cylinder
head and set it at right angle of valve stem being
measured (Fig. 11).
(c) Move valve to and from the indicator. The to­
tal dial indicator reading should not exceed 0.432
mm (0.017 inch). Ream the guides for valves with
oversize stems if dial indicator reading is excessive
or if the stems are scuffed or scored.
Service valves with oversize stems are available
(Fig. 12).
Slowly turn reamer by hand and clean guide thor­
oughly before installing new valve. Ream the valve
guides from standard to 0.381 mm (0,015 inch).
Fig.
11 Measuring Valve Guide Wear

Reamer
O/S

Valve
Guide
Size

0.076
mm
8.026
-
8.052
mm

(0.003 in.) (0.316 -0.317 in.)

0.381
mm 8.331 -8.357 mm
(0.015 in.)
(0.328-0.329
in.)
J9309-30

Fig.
12
Reamer
Sizes

Use a 2 step procedure so the valve guides are
reamed true in relation to the valve seat:

•
Step 1-Ream to 0.0763 mm (0.003 inch).

•
Step 2-Ream to 0.381 mm (0.015 inch).

REFACING
VALVES
/
VALVE
SEATS
The intake and exhaust valves have a 43-1/4° to
43-3/4° face angle and a 44-1/4° to 44-3/4° seat angle
(Fig. 13).

VAL¥ES
Inspect the remaining margin after the valves are
refaced (Fig. 14). Valves with less than 1.190 mm (0.047 inch) margin should be discarded.

VALVE
SEATS

CAUTION:
DO NOT
un-shroud
valves
during
valve

seat
refacing (Fig. 15).
(1) When refacing valve seats, it is important that
the correct size valve guide pilot be used for reseat­ ing stones. A true and complete surface must be ob­
tained.
(2) Measure the concentricity of valve seat using a
dial indicator. Total runout should not exceed 0.051
mm (0.002 inch) total indicator reading.

A
-
SEAT
WIDTH
-
INTAKE
1.016
-
1.524
mm
(0.040
-
0.060
in.)

EXHAUST
1.524
-
2.032
mm
(0.060
-
0.080
in.)

B
-
FACE
ANGLE
(INTAKE
& EXHAUST)
4374°
-
433A°

C
-
SEAT
ANGLE
(INTAKE
& EXHAUST)
4474°
-
44%°
D
-
CONTACT SURFACE

J9309-95
Fig.
13
Valve
Face and
Seat
Angles
i
INTAKE
VALVE
\
MARGIN
/ "

>FACE'
•STEM"
VALVE SPRING
RETAINER LOCK GROOVE EXHAUST
VALVE
J9209-127

Fig.
14 Intake and
Exhaust
Valves
(3) Inspect
the
valve seat with Prussian blue
to de­

termine where
the
valve contacts
the
seat.
To do

this,
coat valve seat LIGHTLY with Prussian blue
then
set
valve
in
place. Rotate
the
valve with light
pressure.
If the
blue
is
transferred
to the
center
of

valve face, contact
is
satisfactory.
If
the blue
is
trans­
ferred
to the top
edge
of
valve face, lower valve seat
with
a 15°
stone.
If
the blue
is
transferred
to
bottom edge
of
valve face raise valve seat with
a 60°
stone.

(4)
When seat
is
properly positioned
the
width
of

intake seats should
be 1.016-1.524 mm (0.040-0.060

inch).
The
width
of the
exhaust seats should
be 1.524-2.032 mm (0.060-0.080
inch).
Fig.
15 Refacing
Valve
Seats

VALVE
SPRING
INSPECTION
Whenever valves have been removed
for
inspection,
reconditioning
or
replacement, valve springs should
be tested.
As an
example
the
compression length
of

the spring
to be
tested
is 1-5/16
inch. Turn table
of

Valve Spring Tester Tool
C-647
until surface
is in
line with
the 1-5/16
inch mark
on the
threaded stud.
Be sure
the
zero mark
is to the
front (Fig.
16).
Place spring over stud
on the
table
and
lift compressing
le­

ver
to set
tone device. Pull
on
torque wrench until
ping
is
heard. Take reading
on
torque wrench
at
this instant. Multiply this reading
by 2.
This will give
the spring load
at
test length. Fractional measure­ ments
are
indicated
on the
table
for
finer adjust­ments. Refer
to
specifications
to
obtain specified
height
and
allowable tensions. Discard
the
springs
that
do not
meet specifications.
SPECIAL

TOOL
C-647

9209-37
Fig.
16 Testing
Valve
Spring
for
Compressed

Length
with
Tool
C-647

INSTALLATION
(1)
Coat valve stems with lubrication
oil and
insert
them
in
cylinder head.

•
3.9L
ENGINE
9 - 27 (2) If valves or seats are reground, check valve
stem height. If valve is too long, replace cylinder
head.
(3) Install new seals on all valve guides. Install
valve springs and valve retainers.
(4) Compress valve springs with Valve Spring
Compressor Tool MD-998772A, install locks and re­
lease tool. If valves and/or seats are ground, measure
the installed height of springs. Make sure the mea­ surement is taken from bottom of spring seat in cyl­
inder head to the bottom surface of spring retainer. If
spacers are installed, measure from the top of spacer.
If height is greater than 42.86 mm (1-11/16 inches), install a 1.587 mm (1/16 inch) spacer in head coun-
terbore. This should bring spring height back to nor­
mal 41.27 to 42.86 mm (1-5/8 to
1-11/16
inch).

VALVE STEM SEAL
/
SPRING REPLACEMENT
This procedure is done with the cylinder head in­
stalled. (1) Set engine basic timing to TDC and remove air
cleaner. (2) Remove cylinder head covers and spark plugs.
(3) Remove coil wire from distributor and secure to
good ground to prevent engine from starting. (4) Using suitable socket and flex handle at crank­
shaft retaining bolt, turn engine so the No.l piston is
at Top Dead Center on the compression stroke. (5) Remove rocker arms.
(6) With air hose attached to an adapter installed
in No.l spark plug hole, apply 620-689 kPa (90-100
psi) air pressure. (7) Using Valve Spring Compressor Tool
MD-998772A, compress valve spring and remove re­
tainer valve locks and valve spring. (8) Install seals on the exhaust valve stem and po­
sition down against valve guides. (9) The intake valve stem seals should be pushed
firmly and squarely over the valve guide using the valve stem as a guide. DO NOT force seal against
top of guide. When installing the valve retainer
locks,
compress the spring only enough to install the
locks.
(10) Follow the same procedure on the remaining 5
cylinders using the firing sequence
1-6-5-4-3-2.
Make sure piston in cylinder is at TDC on the valve spring
that is being removed. (11) Remove adapter from the No.l spark plug

hole.
(12) Install rocker arms.
(13) Install covers and coil wire to distributor.
(14) Install air cleaner.
(15) Road test vehicle.

HYDRAULIC
TAPPETS
Before disassembling any part of the engine to cor­
rect tappet noise, check the oil pressure. If vehicle
has no oil pressure gauge, install a reliable gauge at the pressure sending unit. The pressure should be be­
tween 207-552 kPa (30-80 psi) at 3,000 RPM.
Check the oil level after the engine reaches normal
operating temperature. Allow 5 minutes to stabilize
oil level, check dipstick.
The oil level in the pan should never be above the
FULL mark or below the ADD OIL mark on dipstick.
Either of these 2 conditions could be responsible for
noisy tappets.

OIL
LEWEL

HIGH
If oil level is above the FULL mark, it is possible
for the connecting rods to dip into the oil. With the engine running, this condition could create foam in
the oil pan. Foam in oil pan would be fed to the hy­ draulic tappets by the oil pump causing them to lose
length and allow valves to seat noisily.

LOW
Low oil level may allow oil pump to take in air.
When air is fed to the tappets, they lose length
which allows valves to seat noisily. Any leaks on in­
take side of oil 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 in­
termittent or constant, and usually more than 1 tap­
pet will be noisy. When oil level and leaks have been corrected, operate the engine at fast idle. Run engine
for a sufficient time to allow all of the air inside the
tappets to be bled out.

TAPPET
NOISE DIAGNOSIS
(1) To determine source of tappet noise, operate en­
gine at idle with cylinder head covers removed. (2) Feel each valve spring or rocker arm to detect
noisy tappet. The noisy tappet will cause the affected
spring and/or rocker arm to vibrate or feel rough in
operation.
Worn valve guides or cocked springs are some­
times 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 appre­ ciably reduced, it can be assumed the noise is in
the tappet. Inspect the rocker arm push rod sockets and push rod ends for wear.
(3) 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 or by the
plunger partially sticking in the tappet body cylin­ der. The tappet should be replaced. A heavy click is
caused by a tappet check valve not seating or by for­
eign particles becoming wedged between the plunger
and the tappet body. This will cause the plunger to
stick in the down position. This heavy click will be