Dodge RAM TRUCK 1500 1995 Service Manual page 873

B R
8 J L ENGINE S - 21
TAPPET MOISE 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.
Worm 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 t h e valve spring. If noise is not
appreciably reduced, it can be assumed t h e
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 cylinder.
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
accompanied by excessive clearance between the
valve stem and rocker arm as valve closes. In either
case, tappet assembly should be removed for inspec­
tion and cleaning.
The valve train generates a noise very much like a
light tappet noise during normal operation. Care
must be taken to ensure that tappets are making the
noise. In general, if more than one tappet seems to
be noisy, its probably not the tappets.
REMOVAL
(1) Remove the air cleaner.
(2) Remove cylinder head cover.
(3) Remove rocker assembly and push rods. Iden­
tify push rods to ensure installation in original loca­
tion.
(4) Remove intake manifold.
(5) Remove yoke retainer and aligning yokes.
(6) Slide Hydraulic Tappet Remover/Installer Tool
C-4129-A through opening in cylinder head and seat
tool firmly in the head of tappet.
(7) Pull tappet out of bore with a twisting motion.
If all tappets are to be removed, identify tappets to
ensure installation in original location.
(8) If the tappet or bore in cylinder block is scored,
scuffed, or shows signs of sticking, ream the bore to
next oversize. Replace with oversize tappet.
CAUTION: The plunger and tappet bodies are not
interchangeable. The plunger and valve must al­
ways be fitted to the original body. It is advisable to
work on one tappet at a time to avoid mixing of
parts. Mixed parts are not compatible. DO MOT dis­
assemble a tappet © F T a dirty work bench.
DISASSEMBLE
(1) Pry out plunger retainer spring clip (Fig. 12).
(2) Clean varnish deposits from inside of tappet
body above plunger cap.
(3) Invert tappet body and remove plunger cap,
plunger, check valve, check valve spring, check valve
retainer and plunger spring (Fig. 12). Check valve
could be flat or ball.
(1) Clean all tappet parts in a solvent that will re­
move all varnish and carbon.
(2) Replace tappets that are unfit for further ser­
vice with new assemblies.
(3) If plunger shows signs of scoring or wear, in­
stall a new tappet assembly. If valve is pitted, or
valve seat on end of plunger is prevented from seat­
ing, install a new tappet assembly.
(4) Assemble tappets (Fig. 12).
PLUNGER
SPRING
CHECK
BALL
PLUNGER
RETAINER
SPRING CLIP
LER
TAPPET
BODY
RETAINER
I
PLUNGER
CHECK VALVE
SPRING
PLUNGER
CAP J91G9 220
Fig. 12 Hydraulic Tappet Assembly
INSTALLATION
(1) Lubricate tappets.
(2) Install tappets and push rods in their original
positions. Ensure that the oil feed hole in the side of
the tappet body faces up (away from the crankshaft).
(3) Install aligning yokes with ARROW toward
camshaft.
(4) Install yoke retainer. Tighten the bolts to 23
N-m (200 in. lbs.) torque. Install intake manifold.
(5) Install push rods in original positions.
(6) Install rocker arms.
(7) Install cylinder head cover.
(8) Start and operate engine. Warm up to normal
operating temperature.
CAUTION: To prevent damage to valve mechanism,
engine must not be run above fast idle until all hy­
draulic tappets have filled with oil and have become
quiet.
WALfE THING
(1) Turn crankshaft until the No.6 exhaust valve is
closing and No.6 intake valve is opening.