Dodge RAM TRUCK 1500 1995 Service Manual page 904

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Fig. 10 Refacing Valve Seats
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 compress­
ing lever 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 mea­
surements are Indicated on the table for finer adjust­
ments. Refer to specifications to obtain specified
height and allowable tensions. Discard the springs
that do not meet specifications.
Fig, 11 Testing \Mwe Spfmg for Gompm&sedl Length
(1) Coat valve stems with lubrication oil and Insert
them,
in cylinder bead.
(2) If valves or seats are reground, check valve
stem height. If valve is too long, replace cylinder
head.
(8) 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 I-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 (80-80 psi) at 8,000 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 LMWEL
HiSH
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 intake side
of oil pump through which air can be drawn will cre­
ate 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 Intermittent or
constant, and usually more than 1 tappet will be
noisy. When oil level and leaks have been corrected,
operate the engine at fast Idle. Run engine for a suf­
ficient time to allow all of the air inside the tappets
to be bled out.
TAPPET
moim
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 b e dampened by applying