DaimlerChrysler LH New Yorker 1994, Электронное руководство по обслуживанию

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(15) Install rocker arm covers tighten screws to 14
N
z
m (120 in. lbs.) and connector to ignition coils.
(16) Install Intake Manifold; Refer to Intake Mani-
fold Installation 3.3L Engine, Group 11 Exhaust Sys-
tem and Intake Manifold.
HYDRAULIC TAPPETS
The valve train includes roller tappet assemblies,
aligning yokes and yoke retainer.
Roller tappet alignment is maintained by machined
flats on tappet body being fitted in pairs into six
aligning yokes. The yokes are secured by an align-
ment yoke retainer (Fig. 25).
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
205.8 to 550.6 kPa (30 and 80 psi) 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 engine after
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 the oil pump to take in air
which when fed to the tappets, causes them to be-
come 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 inter-
mittent or constant, and usually more than one tappet
will be noisy. When oil level and leaks have been cor-
rected, 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.
Worn valve guides or cocked springs are
sometimes mistaken for noisy tappets. If such
is the case, noise may be dampened by apply-
ing side thrust on the valve spring. If noise is
not appreciably 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 be-
tween the valve stem and rocker arm as valve closes.
In either case, tappet assembly should be removed
for inspection and cleaning.
TAPPET REMOVAL
(1) Refer to Cylinder Head Removal of this section
to remove intake manifold and cylinder heads for
access to tappets for service.
(2) Remove yoke retainer and aligning yokes.
(3) Use Tool C-4129 to remove tappets from their
bores. If all tappets are to be removed, identify tap-
pets to insure installation in original location.
If the tappet or bore in cylinder block is
scored, scuffed, or shows signs of sticking, ream
the bore to next oversize and replace with over-
size 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 not dis-
assemble a tappet on a dirty work bench.
DISASSEMBLY (FIG. 26)
(1) Pry out plunger retainer spring clip.
Fig. 25 Roller Tappets Aligning Yoke and Retainer
3.3L ENGINE 9 - 17