Chrysler 300M, Dodge Interpid. Manual — part 246

CLEANING

(1) Clean

all

valves

thoroughly

and

discard

burned, warped and cracked valves.

INSPECTION

INSPECTION - VALVES

(1) Measure valve stems for wear (Fig. 32) approx-

imately 60 mm (2.36 in.) below the valve lock
grooves.

(2) Compare measurement to specifications, (Refer

to 9 - ENGINE - SPECIFICATIONS).

NOTE: Valve stems are chrome plated and should
not be polished (Fig. 32).

INSPECTION - VALVE GUIDES

(1) Measure valve stem-to-guide clearance as fol-

lows:

(2) Install valve into cylinder head so it is 15 mm

(0.590 inch.) off the valve seat. A small piece of hose
may be used to hold valve in place.

(3) Attach dial indicator Tool C-3339 to cylinder

head and set it at right angle of valve stem being
measured (Fig. 33).

(4) Move valve to and from the indicator.
(5) Note dial indicator reading and compare to

engine specifications. (Refer to 9 - ENGINE - SPEC-
IFICATIONS)

NOTE: Replace cylinder head if stem-to-guide clear-
ance exceeds specifications, or if guide is loose in
cylinder head.

INSTALLATION

(1) Coat valve stems with clean engine oil and

insert them in cylinder head.

(2) If valves or seats have been reground, check

valve tip height (A) (Fig. 34). If valve tip height is
greater than 43.65 mm (1.7185 in.) intake or 45.98
mm (1.8102 in.) exhaust, grind valve tip until within
specifications. Make sure measurement is taken from
cylinder head surface to the top of valve stem.

(3) Install valve stem seals and valve springs.

(Refer to 9 - ENGINE/CYLINDER HEAD/VALVE
STEM SEALS - INSTALLATION) (Refer to 9 -
ENGINE/CYLINDER

HEAD/VALVE

SPRINGS

-

INSTALLATION)

Fig. 31 Valve Seal and Spring - Installation

1 - VALVE
2 - VALVE RETAINING LOCKS
3 - VALVE SPRING RETAINER
4 - VALVE SPRING
5 - VALVE SEAL AND VALVE SPRING SEAT ASSEMBLY

Fig. 32 Intake and Exhaust Valves

1 - MARGIN
2 - FACE
3 - STEM
4 - VALVE SPRING RETAINER LOCK GROOVES

Fig. 33 Measuring Valve Guide Wear

LH

ENGINE

9 - 31

INTAKE/EXHAUST VALVES & SEATS (Continued)

ROCKER ARM / ADJUSTER
ASSEMBLY

DESCRIPTION

DESCRIPTION - ROCKER ARM

Rocker arms are made of light weight permanent

mold aluminum alloy with a roller type follower oper-
ating against the camshaft (Fig. 35). The valve actu-
ating end of the rocker arms are machined to retain
hydraulic lash adjusters, eliminating the need for
manual valve lash adjustment.

DESCRIPTION - ROCKER ARM SHAFTS

The rocker arm shafts (Fig. 36) are tubular steel

and are supported by several forged aluminum alloy
pedestals, which are fastened to the cylinder head.
Four shafts are used, one for each intake and
exhaust rocker arm bank on each cylinder head. The
shafts are hollow to provide a duct for lubricating oil
flow from the cylinder head to the valve mechanisms.
One hollow dowel per pedestal is used to locate the
pedestal to the cylinder head, orient the exhaust
rocker shaft, and serve as a cam bearing oil feed pas-
sage.

DIAGNOSIS AND TESTING

LASH ADJUSTER (TAPPET) NOISE DIAGNOSIS

Proper noise diagnosis is essential in locating the

source of a NVH complaint. Locating a lash adjuster
(tappet) type noise can sometimes be difficult. As a
result, an initial misdiagnosis may occur.

Refer to the following chart indicating possible lash

adjuster (tappet) noise sources and possible sources
that could lead to a misdiagnosis.

Refer to Lash Adjuster (Tappet) Noise Chart for

Possible Causes and Correction of a lash adjuster
(tappet) type noise.

Fig. 34 Checking Valve Tip Height and Valve Spring

Installed Height

1 - SPRING RETAINER
2 - GARTER SPRING
3 - VALVE SPRING SEAT TOP
4 - CYLINDER HEAD SURFACE

Fig. 35 Rocker Arm Assembly

1 - RETAINER
2 - SWIVEL PAD
3 - ROLLER

Fig. 36 Rocker Arms and Shafts

9 - 32

ENGINE

LH

INTAKE/EXHAUST VALVES & SEATS (Continued)

POSSIBLE NOISE SOURCES

POSSIBLE NOISE MISDIAGNOSIS SOURCES

Spongy/soft/aerated lash adjusters.

SRV valve axle chatter.

Missing lash adjuster swivel contact pads.

Exhaust rocker arm-to-cylinder head cover contact.

Intake rocker-to-camshaft bearing journal contact.

Piston pin bore fit.

Rocker arm bind-up.

Timing drive hydraulic tensioner tick.

Intake rocker arm-to-spark plug tube contact.

Accessory drive belt deterioration.

Excessive cam end play.

Piston-to-bore clearance knock.

Broken valve spring.

Crankshaft bearing noise.

Broken/loose camshaft sprocket bolt.

Incomplete cam lobe machining.

Cracked lash adjuster cartridge body.

LASH ADJUSTER (TAPPET) NOISE CHART

POSSIBLE CAUSES

CORRECTION

1. Engine oil level—too high or too low. This may
cause aerated oil to enter the adjusters and cause
them to be spongy.

1. Check and correct engine oil level.

2. Insufficient running time after rebuilding cylinder
head.

2. Low speed running of up to 1 hour may be required to
fully evacuate trapped air from the valve train system. During
this time, turn engine off and let set for a few minutes before
restarting. Repeat this several times after engine has
reached normal operating temperature.

3. Air trapped in lash adjuster (after 1 hour run
time).

3. See below:
(a) Check lash adjusters for sponginess while installed in
cylinder head. Depress part of rocker arm over adjuster.
Normal adjusters should feel very firm. Very spongy
adjusters can be bottomed out easily.

(b) Before proceeding, perform Lash Adjuster Bleeding
procedure.

(c) If lash adjuster(s) are still spongy, replace with new
adjuster/rocker arm assembly*.

4. Low oil pressure

4. See below:
(a) Check and correct engine oil level.

(b) Check engine oil pressure.

(c) Check for excessive bearing clearance and correct.

(d) Check for worn oil pump.

5. Oil passage to cylinder head(s) plugged with
debris.

5. Check cylinder head oil passages and cylinder head
gasket restrictor for blockage. Clean or replace as
necessary.

6. Worn valve guide(s).

6. Ream guide(s) and replace valve(s) with oversize valves
and seal(s).

7. Air injested into oil due to broken or cracked oil
pump pickup tube.

7. Inspect pickup tube and replace as necessary.

8. Collapsed lash adjuster due to debris injestion.

8. Clean debris from engine and replace lash adjuster/rocker
assembly*.

9. Intake rocker arm roller clevis ear(s) contacting
camshaft bearing journal(s) on side.

9. Inspect camshaft end play and all valve train components
for wear. Replace as necessary.

*Lash adjusters are serviced with the rocker arms—do not disassemble.

LH

ENGINE

9 - 33

ROCKER ARM / ADJUSTER ASSEMBLY (Continued)

STANDARD PROCEDURE - HYDRAULIC LASH
ADJUSTER BLEEDING

Use this procedure to manually bleed aerated oil

from the lash adjuster and remove sponginess.

(1) Run the engine, bringing it to operating tem-

perature in order to freshly pressurize and warm the
valvetrain system oil supply.

(2) Remove cylinder head cover(s).
(3) Ensure the rocker arm is positioned on the

base circle of the cam (Fig. 37). Rotate engine as nec-
essary.

(4) For intake rocker arm positions:

(a) Adjust Special Tool 8351 Release Probe’s

gauge pin to extend approximately 20 mm (0.787
in.). Then, carefully insert the release probe gauge
pin into the lash adjuster service access hole (Fig.
38).

CAUTION: If probe tip breaks off within the lash
adjuster, replace the affected rocker arm.

(b) Gently unseat lash adjuster’s internal check

ball.

(c) While

the

internal

check

ball

is

held

unseated, press the rocker arm into the valve tip,
allowing the lash adjuster to fully collapse. Hold
this fully collapsed position for about one second,
or longer.

(d)

Slowly release the rocker arm, thereby

allowing the lash adjuster to extend, which in turn
refills the high pressure chamber with non-aerated
oil.

(e) Remove probe to allow check ball to seat.
(f) Recheck for sponginess. If the lash adjuster

sponginess is not completely or nearly eliminated,
then repeat procedure.

(g)

If the spongy condition cannot be removed,

replace effected rocker arm(s).
(5) For exhaust rocker arm positions:

(a) Adjust Special Tool 8351 Release Probe

gauge pin to extend approximately 20 mm (0.787
in.). Then, using two release probes, carefully
insert gauge pins into the lash adjuster service
access holes (Fig. 38).

CAUTION: If probe tip breaks off within the lash
adjuster, replace the affected rocker arm.

(b) Gently unseat BOTH lash adjuster’s internal

check ball at the same time.

(c) While

the

internal

check

ball

is

held

unseated, press the rocker arm into the valve tip,
allowing the lash adjuster to fully collapse. Hold
this fully collapsed position for about one second,
or longer.

(d) Slowly release the rocker arm, thereby allow-

ing the lash adjuster to extend, which in turn
refills the high pressure chamber with non-aerated
oil.

(e) Remove probes to allow check balls to seat.
(f) Recheck for sponginess. If the lash adjuster

sponginess is not completely or nearly eliminated,
then repeat procedure.

(g) If the spongy condition cannot be removed,

replace effected rocker arm(s).
(6) Install cylinder head cover(s).

REMOVAL

CAUTION: The rocker arm shafts are hollow and are
used as lubrication oil passages. The rocker arm
and shaft assembly on the RIGHT side of the
engine has an oil passage hole from the cylinder
head to the third rocker shaft support. The rocker
arm shaft assembly on the LEFT side of the engine
has an oil passage hole from the cylinder head to
the second rocker shaft support.

Fig. 37 Rocker Arm Positioned On Base Circle Of

Camshaft

1 - CAMSHAFT BASE CIRCLE
2 - HIGH-PRESSURE CHAMBER

9 - 34

ENGINE

LH

ROCKER ARM / ADJUSTER ASSEMBLY (Continued)