Jeep Cherokee 2000 Service Manual - page 330
CONDITION
POSSIBLE CAUSE
CORRECTION
1. VERY HIGH FREQUENCY
WHINE BEFORE ENGINE
STARTS; ENGINE STARTS OK.
1. Excessive distance between pinion
gear and flywheel/drive plate gear.
1. Move starter motor toward
flywheel/drive plate by removing
shim(s), if possible.
2. VERY HIGH FREQUENCY
WHINE AFTER ENGINE STARTS
WITH IGNITION KEY RELEASED.
ENGINE STARTS OK.
2. Insufficient distance between
starter motor pinion gear and
flywheel/drive plate runout can cause
noise to be intermittent.
2. Shim starter motor away from
flywheel/drive plate. Inspect
flywheel/drive plate for damage;
bent, unusual wear, and excessive
runout. Replace flywheel/drive
plate as necessary.
3. A LOUD “WHOOP” AFTER
ENGINE STARTS WHILE
STARTER MOTOR IS ENGAGED.
3. Most probably cause is defective
overrunning clutch.
3. Replace starter motor.
4. A “RUMBLE,” “GROWL,” OR
“KNOCK” AS STARTER MOTOR
COASTS TO STOP AFTER
ENGINE STARTS.
4. Most probable cause is bent or
unbalanced starter motor armature.
4. Replace starter motor.
NOTE:
A high frequency whine during cranking is normal for this starter motor.
FIG. 9 STARTER MOTOR NOISE DIAGNOSIS
(1) If the complaint is similar to Condition 1, the
starter motor must be moved toward the starter ring
gear by removing shims from both starter mounting
pads on the engine block (Fig. 10). Refer to Starter
Motor in the index of this service manual for the
location of the proper starter motor removal and
installation procedures.
NOTE: The shim thickness is 0.381 mm (0.015 in.).
These shims may be stacked if additional thickness
is required.
(2) If the complaint is similar to Condition 2, the
starter motor must be moved away from the starter
ring gear. This is done by installing shim(s) across
both starter mounting pads on the engine block.
More than one shim may be required. Refer to
Starter Motor in the index of this service manual
for the location of the proper removal and installa-
tion procedures.
NOTE: This is a condition that will generally cause
broken
starter
(flywheel/torque
converter
drive
plate) ring gear teeth or broken starter motor hous-
ings.
STARTER MOTOR
Correct starter motor operation can be confirmed
by performing the following free running bench test.
This test can only be performed with the starter
motor removed from the vehicle. Refer to Starting
System in the index of this service manual for the
location of the proper starter motor specifications.
CAUTION: The 2.5L engine uses a permanent mag-
net starter. Permanent magnet starters are highly
sensitive to hammering, shocks, external pressure
and reverse polarity. This starter motor must never
be clamped in a vise by the starter field frame. The
starter should only be clamped by the mounting
flange. Do not reverse the battery cable connec-
tions to this starter motor when testing. The perma-
nent magnets may be damaged and the starter
rendered unserviceable if it is subjected to any of
these conditions.
Fig. 10 Starter Motor Shim
1 – STARTER MOTOR SHIM
XJ
STARTING SYSTEMS
8B - 9
DIAGNOSIS AND TESTING (Continued)