Important: If you have not completed the Vibration Analysis tables as indicated
and reviewed Vibration Diagnostic Aids, refer to
Vibration Diagnostic Aids
BEFORE proceeding.
If you have not been able to duplicate the vibration concern or have
only been able to duplicate the concern intermittently, review the following
information.
Most vibration concerns that cannot be duplicated are due to either
specific conditions that are not present during the duplicating attempts,
or due to not following the procedures designed to duplicate concerns properly
and in the sequence indicated.
Specific Conditions Can Affect the Condition
Consider the following conditions which may not have been present while
attempts were made to duplicate the vibration concern. Attempt to obtain
more specific information from the customer as to the EXACT conditions that
are present when they experience the vibration which they are concerned about.
Attempt to duplicate the vibration concern again while recreating the EXACT
conditions necessary, except those which pose a safety concern or are outside
the boundaries of normal operating conditions, such as loading the vehicle
beyond its designed weight ratings, etc.
Most attempts to duplicate a vibration concern are made after the vehicle
has been driven to the dealership and perhaps even sat inside the building
for a time; the vehicle may be too warm to detect the concern during duplication
efforts. The opposite could also occur; perhaps the vehicle has sat out in
the cold for a time and fails to reach full operating temperatures during
attempts to duplicate the concern.
Temperature, Ground-Out, Accessory Load
Flat Spots on Tires
Tires which have sat and been cool for a time can develop flat spots.
Irregular Wear on Tire Treads
Tires which have sat and been cool for a time will be stiffer and any
irregular wear conditions will be more noticeable than they will be once
the tires have warmed and softened.
Exhaust System Growth
Exhaust systems may exhibit a ground-out condition when cool which goes
away once the system hot. The opposite may be true that the exhaust system
is fine when cool but a ground-out condition occurs once the system reaches
operating temperatures. Exhaust systems can grow by 2½-5 cm
(1-2 in) when hot.
Engine-Driven Accessory Noises
| | An engine accessory drive belt, or belts could exhibit a whipping condition
if a belt is deteriorating and deposits are building up on the underside
of the belt. |
| • | Loose Mounting Brackets or Component Ground-Out |
| | Engine-driven accessories such as a generator, a power steering pump,
or an air conditioning compressor could exhibit noise conditions due to either
loose mounting brackets or due to related components of the system in a ground-out
condition during certain operation of that accessory system. |
| | These accessories could exhibit noise conditions when cool which go
away once they are fully warmed-up, or the opposite may be true. |
| • | Load on an Accessory Component |
| | These accessories could exhibit a noise condition while under a heavy
load - perhaps when combined with a cool or fully warmed-up condition. |
| • | Bent or Misaligned Pulleys |
| | Bent or mis-aligned pulleys in one or more engine-driven accessory
systems could contribute to a noise or vibration condition. |
| • | Fluid Level in Accessory Systems |
| | These accessories could exhibit a noise condition due to an abnormal
amount of fluid contained in the system of which the accessory is a part. |
| - | An improper power steering fluid level could produce noises in
the power steering system. |
| - | An improper air conditioning refrigerant level or an excessive
amount of refrigerant oil could produce noises or possibly vibrations in
the air conditioning system. |
| • | Incorrect Fluid Type in Accessory Systems |
| | These accessories could exhibit a noise condition due to the incorrect
type of fluid contained in the system of which the accessory is a part. |
Vehicle Payload
The vibration concern may only occur when the vehicle is carrying heavy
payloads or towing a trailer; the vehicle may have been empty during duplication
efforts.
Heavy Payload
The vehicle may have been empty during attempts to duplicate the vibration
concern, but the customer may actually experience the vibration concern while
the vehicle is carrying a large payload.
Trailer Towing
The customer may experience the vibration concern only while towing
a trailer.
Roadway Selection
The selection of roadways used to perform the vibration duplication
procedures is likely to be in the near vicinity of the dealership and may
not provide a road surface that is close enough to the surface on which the
customer usually drives the vehicle.
The customer may only experience the vibration on a particular roadway.
Perhaps the roadway is overly crowned or is very bumpy or rough.
