Jeep Cherokee 2000 Service Manual - page 1117
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 4 bars (50 psi) at 3000 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 condi-
tions could be responsible for noisy tappets:
OIL LEVEL 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
hydraulic tappets by the oil pump causing them to
lose length and allow valves to seat noisily.
OIL LEVEL 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.
HYDRAULIC TAPPETS
REMOVAL
(1) Disconnect the negative battery cable.
(2) Discharge
the
air
conditioning
system,
if
equipped. Refer to Group 24, Heating and Air Condi-
tioning for procedure.
(3) If equipped with air conditioning, remove the
A/C lines at the compressor and cap.
(4) Remove the A/C line bracket attached to the
cylinder head cover and move the lines away from
the cylinder head.
(5) Remove cylinder head cover. Refer to cylinder
head cover removal and installation procedure in this
section.
(6) Remove the rocker assemblies and push rods.
Refer to rocker arms and push rod removal and
installation procedure in this section. Identify push
rods to ensure installation in original location.
(7) Remove cylinder head, intake manifold, and
exhaust manifold. Refer to cylinder head removal
and installation in this section.
(8) Remove the tappet retainers (Fig. 26).
(9) Slide Hydraulic Tappet Remover/Installer Tool
through opening in block and seat tool firmly in the
head of tappet.
(10) Pull the tappet out of the bore with a twisting
motion. If all tappets are to be removed, identify tap-
pets to ensure installation in original location.
CAUTION: The plunger and tappet bodies are not
interchangeable.
The
plunger
and
valve
must
always 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.
Fig. 25 Tappet And Rocker Arm Assembly
Fig. 26 Tappet And Retainer
XJ
ENGINE
9 - 23
REMOVAL AND INSTALLATION (Continued)