Jeep Cherokee 2000 Service Manual - page 1105
CONDITION
POSSIBLE CAUSES
CORRECTION
EXCESSIVE ENGINE
NOISES
1. Drive belt squeal, insufficient
tension or abnormally high loading.
1. Check the automatic tensioner and
inspect the drive belt. Make sure water
pump, tensioner pulley, fan hub and
generator turn freely.
2. Intake air or exhaust leaks.
2. Refer to Excessive Exhaust smoke
(Engine Diagnosis Performance).
3. Turbocharger noise.
3. Check turbocharger impeller and
turbine wheel for housing contact.
Repair/replace as required.
4. Gear train noise.
4. Visually inspect and measure gear
backlash. Replace gears as required.
5. Power function knock.
5. Check/replace rod and main
bearings.
GENERATOR NOT
CHARGING OR
INSUFFICIENT CHARGING
1. Loose or corroded battery.
1. Clean/tighten battery connection.
2. Generator belt slipping.
2. Check/replace automatic abelt
tensioner.
Check/replace and adjust belt.
3. Generator pulley loose on shaft.
3. Tighten pulley
4. Improperly operating generator.
4. Check/replace generator.
TAPPET NOISE
(1) To determine source of tappet noise, operate
engine 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.
NOTE: 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 apprecia-
bly 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.
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.
SERVICE PROCEDURES
VALVE SERVICE
This procedure is done with the engine cylinder
head removed from the block.
DISASSEMBLY
(1) Remove the engine cylinder head from the cyl-
inder block. Refer to cylinder head removal and
installation in this section.
(2) Use Valve Spring Compressor Tool and com-
press each valve spring.
(3) Remove the valve locks, retainers, and springs.
(4) Use an Arkansas smooth stone or a jewelers
file to remove any burrs on the top of the valve stem,
especially around the groove for the locks.
(5) Remove the valves, and place them in a rack in
the same order as removed.
VALVE CLEANING
(1) Clean all carbon deposits from the combustion
chambers, valve ports, valve stems, valve stem
guides and head.
(2) Clean all grime and gasket material from the
engine cylinder head machined gasket surface.
XJ
ENGINE
9 - 11
DIAGNOSIS AND TESTING (Continued)