Dodge RAM TRUCK 1500 1995 Service Manual page 933

BR
S J L ENGINE 9 - S I
(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
1.524-2.082 mm (0.060-0.080 inch).
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
Universal Valve Spring Tester Tool 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. 11). 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 measurements
are indicated on the table for finer adjustments. Re­
fer to specifications to obtain specified height and al­
lowable tensions. Discard the springs that do not
meet specifications.
Fig. 11 Testing Valve Spring for Compressed Length
INSTALLATION
(1) Coat valve stems with lubrication oil and insert
them in cylinder head.
(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).
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
between 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 L E V E L
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, causes them to lose
length and allows valves to seat noisily. Any leaks on
intake side of oil pump through which air can be
drawn will create the same tappet action. When tap­
pet noise is due to aeration, it may be intermittent or
constant, and usually more than 1 tappet will be
noisy. When oil level and leaks have been corrected,
engine should be operated at fast idle for sufficient
time. This allows all of the air inside of 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
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
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.
(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.