Jeep Cherokee 2000, Service Manual

Page: 216 / 1528

CLUTCH CONTAMINATION
Fluid contamination is a frequent cause of clutch
malfunctions. Oil, water, or clutch fluid on the clutch
disc and pressure plate surfaces will cause chatter,
slip and grab.
During inspection, note if any components are con-
taminated with oil, hydraulic fluid, or water/road
splash.
Oil contamination indicates a leak at either the
rear main seal or transmission input shaft. Oil leak-
age produces a residue of oil on the housing interior
and on the clutch cover and flywheel. Heat buildup
caused by slippage between the cover, disc and fly-
wheel, can sometimes bake the oil residue onto the
components. The glaze-like residue ranges in color
from amber to black.
Road splash contamination means dirt/water is
entering the clutch housing due to loose bolts, hous-
ing cracks, or through hydraulic line openings. Driv-
ing through deep water puddles can force water/road
splash into the housing through such openings.
Clutch fluid leaks are usually from damaged slave
cylinder push rod seals. This type of leak can only be
confirmed by visual inspection.
IMPROPER CLUTCH RELEASE OR
ENGAGEMENT
Clutch release or engagement problems are caused
by wear, or damage to one or more clutch compo-
nents. A visual inspection of the release components
will usually reveal the problem part.
Release problems can result in hard shifting and
noise. Items to look for are: leaks at the clutch cylin-
ders and interconnecting line; loose slave cylinder
bolts; worn/loose release fork and pivot stud; dam-
aged release bearing; and a worn clutch disc, or pres-
sure plate.
Normal condensation in vehicles that are stored or
out of service for long periods of time can generate
enough corrosion to make the disc stick to the fly-
wheel, or pressure plate. If this condition is experi-
enced, correction only requires that the disc be
loosened manually through the inspection plate open-
ing.
Engagement problems usually result in slip, chat-
ter/shudder, and noisy operation. The primary causes
are clutch disc contamination; clutch disc wear; mis-
alignment, or distortion; flywheel damage; or a com-
bination of the foregoing. A visual inspection is
required to determine the part actually causing the
problem.
CLUTCH MISALIGNMENT
Clutch components must be in proper alignment
with the crankshaft and transmission input shaft.
Misalignment caused by excessive runout or warpage
of any clutch component will cause grab, chatter and
improper clutch release.
CLUTCH HOUSING MISALIGNMENT
Clutch housing alignment is important to proper
clutch operation. The housing maintains alignment
between the crankshaft and transmission input
shaft. Misalignment can cause clutch noise, hard
shifting, incomplete release and chatter. It can also
result in premature wear of the pilot bearing, cover
release fingers and clutch disc. In severe cases, mis-
alignment can also cause premature wear of the
transmission input shaft and front bearing.
Housing misalignment is generally caused by
incorrect seating on the engine or transmission, loose
housing bolts, missing alignment dowels, or housing
damage. Infrequently, misalignment may also be
caused by housing mounting surfaces that are not
completely parallel. Misalignment can be corrected
with shims.
CLUTCH FLYWHEEL RUNOUT
Check flywheel runout whenever misalignment is
suspected. Flywheel runout should not exceed 0.08
mm (0.003 in.). Measure runout at the outer edge of
the flywheel face with a dial indicator. Mount the
indicator on a stud installed in place of one of the fly-
wheel bolts.
Common causes of runout are:
•
heat warpage
•
improper machining
•
incorrect bolt tightening
•
improper seating on crankshaft flange shoulder
•
foreign material on crankshaft flange
Flywheel machining is not recommended. The fly-
wheel clutch surface is machined to a unique contour
and machining will negate this feature. However,
minor flywheel scoring can be cleaned up by hand
with 180 grit emery, or with surface grinding equip-
ment. Remove only enough material to reduce scor-
ing (approximately 0.001 - 0.003 in.). Heavy stock
removal is not recommended. Replace the flywheel
if scoring is severe and deeper than 0.076 mm (0.003
in.). Excessive stock removal can result in flywheel
cracking or warpage after installation; it can also
weaken the flywheel and interfere with proper clutch
release.
Clean the crankshaft flange before mounting the
flywheel. Dirt and grease on the flange surface may
cock the flywheel causing excessive runout. Use new
bolts when remounting a flywheel and secure the
bolts with Mopar
t
Lock And Seal. Tighten flywheel
bolts to specified torque only. Overtightening can dis-
tort the flywheel hub causing runout.
6 - 6 CLUTCH
XJ
DIAGNOSIS AND TESTING (Continued)