Drive Belt Chirping, Squeal, and Whine Diagnosis
Diagnostic Aids
• |
A chirping or squeal noise may
be intermittent due to moisture on the drive belts or the pulleys.
It may be necessary to spray a small amount of water on the drive
belts in order to duplicate the customers concern. If spraying
water on the drive belt duplicates the symptom, cleaning the belt
pulleys may be the probable solution. |
• |
If the noise is intermittent,
verify the accessory drive components by varying their loads making
sure they are operated to their maximum capacity. An overcharged
A/C system, power steering system with a pinched hose or wrong
fluid, or a generator failing are suggested items to
inspect. |
• |
A chirping, squeal or whine
noise may be caused by a loose or improper installation of a body
or suspension component. Other items of the vehicle may also cause
the noise. |
• |
The drive belts will not cause
a whine noise. |
Test Description
The numbers below refer to the step numbers on the diagnostic
table.
2 The noise may not be
engine related. This step is to verify that the engine is making
the noise. If the engine is not making the noise do not proceed
further with this table.
3 The noise may be an
internal engine noise. Removing the drive belts one at a time and
operating the engine for a brief period will verify the noise is
related to the drive belt. When removing the drive belt the water
pump may not be operating and the engine may overheat. Also DTCs
may set when the engine is operating with the drive belts
removed.
4 Inspect all drive belt
pulleys for pilling. Pilling is the small balls or pills or it can
be strings in the drive belt grooves from the accumulation of
rubber dust.
6 Misalignment of the
pulleys may be caused from improper mounting of the accessory drive
component, incorrect installation of the accessory drive component
pulley, or the pulley bent inward or outward from a previous
repair. Test for a misaligned pulley using a straight edge in the
pulley grooves across two or three pulleys. If a misaligned pulley
is found refer to that accessory drive component for the proper
installation procedure for that pulley.
10 Inspecting of the
fasteners can eliminate the possibility that a wrong bolt, nut,
spacer, or washer was installed.
12 Inspecting the pulleys
for being bent should include inspecting for a dent or other damage
to the pulleys that would prevent the drive belt from not seating
properly in all of the pulley grooves or on the smooth surface of a
pulley when the back side of the belt is used to drive the
pulley.
14 This test is to verify
that the drive belt tensioner operates properly. If the drive belt
tensioner is not operating properly, proper belt tension may not be
achieved to keep the drive belt from slipping which could cause a
squeal noise.
15 This test is to verify
that the drive belt is not too long, which would prevent the drive
belt tensioner from working properly. Also if an incorrect length
drive belt was installed, it may not be routed properly and may be
turning an accessory drive component in the wrong direction.
16 Misalignment of the
pulleys may be caused from improper mounting of the accessory drive
component, incorrect installation of the accessory drive component
pulley, or the pulley bent inward or outward from a previous
repair. Test for a misaligned pulley using a straight edge in the
pulley grooves across two or three pulleys. If a misaligned pulley
is found refer to that accessory drive component for the proper
installation procedure for that pulley.
17 This test is to verify
that the pulleys are the correct diameter or width. Using a known
good vehicle compare the pulley sizes.
19 Replacing the drive
belt when it is not damaged or there is not excessive pilling will
only be a temporary repair.
Step
|
Action
|
Yes
|
No
|
|
Caution: Do
not use belt dressing on the drive belt. Belt dressing causes the
breakdown of the composition of the drive belt. Failure to follow
this recommendation will damage the drive belt. |
DEFINITION: The following items are indications of chirping:
• |
A high pitched noise that is heard once per
revolution of the drive belt or a pulley. |
• |
Chirping may occur on cold damp start-ups and will
subside once the vehicle reaches normal operating temp. |
DEFINITION: The following items are indications of drive belt
squeal:
• |
A loud screeching noise that is caused by a
slipping drive belt. This is unusual for a drive belt with multiple
ribs. |
• |
The noise occurs when a heavy load is applied to
the drive belt, such as an air conditioning compressor engagement
snapping the throttle, or slipping on a seized pulley or a faulty
accessory drive component. |
DEFINITION: The following items are indications of drive belt
whine:
• |
A high pitched continuous noise. |
• |
The noise may be caused by an accessory drive
component failed bearing. |
|
1
|
Did you review the Drive Belt Symptom operation and perform the
necessary inspections?
|
Go to Step 2
|
Go to
Symptoms - Engine Mechanical
|
2
|
Verify that there is a chirping, squeal or whine noise.
Does the engine make the chirping squeal or whine noise?
|
Go to Step 3
|
Go to Diagnostic Aids
|
3
|
|
1. |
Remove the drive belt. |
|
2. |
Operate the engine for no longer than 30-40
seconds. |
|
3. |
Repeat this test if necessary by removing the
remaining belt(s). |
Does the chirping, squeal or whine noise still exist?
|
Go to
Symptoms - Engine Mechanical
|
Go to Step 4
|
4
|
If diagnosing a chirping noise, inspect for severe pilling
exceeding 1/3 of the belt groove depth.
If diagnosing a squeal or whine noise, proceed to step 13.
Do the belt grooves have pilling?
|
Go to Step 5
|
Go to Step 6
|
5
|
Clean the drive belt pulleys with a suitable wire brush.
Did you complete the repair?
|
Go to Step 20
|
Go to Step 6
|
6
|
Inspect for misalignment of the pulleys.
Are any of the pulleys misaligned?
|
Go to Step 7
|
Go to Step 8
|
7
|
Replace or repair any misaligned pulleys.
Did you complete the repair?
|
Go to Step 20
|
Go to Step 8
|
8
|
Inspect for bent or cracked brackets.
Did you find any bent or cracked brackets?
|
Go to Step 9
|
Go to Step 10
|
9
|
Replace any bent or cracked brackets.
Did you complete the repair?
|
Go to Step 20
|
Go to Step 10
|
10
|
Inspect for improper, loose or missing fasteners.
Did you find the condition?
|
Go to Step 11
|
Go to Step 12
|
11
|
|
2. |
Replace any improper or missing fasteners. |
Did you complete the repair?
|
Go to Step 20
|
Go to Step 12
|
12
|
Inspect for a bent pulley.
Did you find the condition?
|
Go to Step 18
|
Go to Step 19
|
13
|
Inspect for an accessory drive component seized bearing or a
faulty accessory drive component.
If diagnosing a whine noise and the condition still exist, proceed
to Diagnostic Aids.
Did you find and correct the condition?
|
Go to Step 20
|
Go to Step 14
|
14
|
Test the drive belt tensioner for proper operation.
Did you find and correct the condition?
|
Go to Step 20
|
Go to Step 15
|
15
|
Inspect for the correct drive belt length.
Did you find and correct the condition?
|
Go to Step 20
|
Go to Step 16
|
16
|
Inspect for misalignment of a pulley.
Did you find and correct the condition?
|
Go to Step 20
|
Go to Step 17
|
17
|
Inspect for the correct pulley size.
Did you find and correct the condition?
|
Go to Step 20
|
Go to Diagnostic Aids
|
18
|
Replace the bent pulley.
Did you complete the repair?
|
Go to Step 20
|
Go to Step 19
|
19
|
Replace the drive belt. Refer to
Generator, Air Conditioning Compressor, and Power Steering Pump
Belt Replacement .
Did you complete the repair?
|
Go to Step 20
|
Go to Diagnostic Aids
|
20
|
Operate the system in order to verify the repair.
Did you correct the condition?
|
System OK
|
Go to Step 3
|
|
|
|