| Subject: | Correction of Various Front End Noises |
| Models: | 1997-1999 Buick Century/Regal |
| 1998-1999 Oldsmobile Intrigue |
| 1997-1999 Pontiac Grand Prix |
This bulletin is intended to provide information to help
identify and correct various front end noises in 1997-1999 Buick, Pontiac,
and Oldsmobile midsize vehicles. Though many components are shared between
these vehicles, specific noise related customer concerns may be present in
only a select group of vehicles. This bulletin provides specific information
regarding the make and model affected with any known cut off points (VIN #
or Date). It is not intended to contain all possible sources of front end
noise, but will identify some of the harder to diagnose items.
The subjects of this bulletin include the following:
| • | WHINE/WHISTLE or TONE at 20 mph with slight steering input
(Magnasteer® only). |
| • | A CLUNK that can be produced when the vehicle's engine is running,
but not when it is off. |
| • | A CLUNK that can be produced, both when the engine is running
and when it is off. |
| • | A CLUNK/RATTLE/POP heard during low speed maneuvers or while driving
down the road. |
| • | A CHIRPING or SQUEAKING sound from the front suspension when hitting
sharp bumps. |
| • | SNAPS, POPS and CREAKS from the front struts. |
| • | A VIBRATION or ROUGHNESS in the steering. |
Correction
The following is information on the source and correction of various
noises that may be found in midsize vehicles. Please see the applicable Service
Manual for the repair procedure in each case.
Whine/Whistle, or Tone at 20 mph With Slight Steering Input
(Magnasteer® only) -- (1998 Buick Regal GS, 1998 Oldsmobile Intrigue)
A whine or whistle may be heard in the passenger compartment of the
vehicle. The tone may resemble a test tone and is most noticeable at 20 mph
with slight steering inputs. The noise originates in the Magnasteer® Variable
Assist Steering Gear.
Important: For the Buick Regal, this condition applies only to a two month production
of the GS model. During that time, the Oldsmobile Intrigue intermediate shaft
was substituted for the Buick part. Check the concerned vehicle for a multi-splined
intermediate shaft in place of the standard DOUBLE-D style shaft. Replace
the splined shaft as instructed under "A Clunk that can be produced,
both when the engine is running and when it is off" in this bulletin.
Replace the shaft regardless of it's date code.
| • | To diagnose this condition, disconnect the Magnasteer® Variable
Assist (MSVA) harness (at the MSVA pigtail) from the steering gear and test
drive the vehicle again. If the noise has disappeared, then the MSVA system
is the source. |
| • | To correct this condition, replace the Electronic Brake and Traction
Control Module with a revised module (P/N 9353511). Refer to the Labor
Time Guide for applicable operation number and time allowance. |
A Clunk That Can be Produced When the Vehicle's Engine is Running But
Not When It's Off (1998 Buick Regal GS, 1998 Oldsmobile Intrigue)
This type of noise is likely to be a steering gear condition; specifically
too much clearance between the seal on the power piston and the groove that
the seal rides in. This excessive clearance lets the piston seal knock inside
the groove during turns.
| • | With the vehicle stationary and the engine running, turn the steering
wheel rapidly back and forth over it's center position. Complete a cycle of
both directions about once a second. The wheel must be turned this quickly
in order to bring about the noise. Next, repeat this rapid turning over center
with the engine off. |
| • | If the clunk was present with the engine on, but not when turned
off, the rack may be the source. Verify the date of vehicle manufacture. This
condition was corrected in production by February 1, 1998. If the vehicle
is older then this date and has not had a steering rack replacement, replace
the rack. If the vehicle is newer than February 1, 1998 refer to the applicable
Service Manual and follow the normal diagnostic procedures before changing
the rack. |
A Clunk That Can be Produced Both When the Engine is Running and When
It's Off (1998 Buick Regal, 1998 Oldsmobile Intrigue)
Important: The above condition applies only to a two month production run of the
1998 Buick Regal. During this period, the splined intermediate shafts were
installed in place of the standard DOUBLE-D style shaft. These vehicles were
all equipped with the early version of the splined shaft which is prone to
the clunk noise. If a Buick Regal with this condition is encountered, replace
the shaft with the DOUBLE-D style that is designated in the GM Parts Manual
as original equipment.
This type of clunk is likely to be caused by the intermediate shaft.
This clunk may be caused by too much clearance between the splined inner and
outer parts of the slider joint. The additional clearance allows them to knock
against each other during turns.
| • | The correction is to replace the intermediate shaft with one built
since the middle of October, 1998. |
| • | Check the shaft's date code to assure that it is a good shaft.
The code can be recognized by the fact that it's laser-etched, rather than
stamped on the end of the shaft. The shaft must have been built on or later
than the 280th day of 1998 (example: "282A8"). In this example,
the "282" represents the 282nd day and the final "8"
represents 1998. |
A Clunk/Rattle/Pop Heard During Low Speed Maneuvers or While Driving
Down The Road (1998 Oldsmobile Intrigue)
This noise in it's various forms is likely to be caused by either under-torqued
bolts in the front strut mounts or by an older intermediate shaft. The following
is how to distinguish between the two possible causes:
| • | Begin diagnosis by verifying the torque of the front strut mounting
bolts which may have been under-torqued during assembly. |
Tighten
Tighten the front strut mounting bolts to 33 N·m(24 lb ft).
| • | If the clunk/rattle remains once the mounting bolts are correctly
torqued, the cause may be a second condition with the intermediate shaft.
Before it can be heard, this condition can be felt as a sharp knocking or
tapping feel in the steering wheel. Eventually it will become an audible rattle
or tapping. This noise is most obvious at low speed. The rattle or tapping
is heard when driving over a series of small bumps, but may change to a clunk
or pop with light brake application or acceleration. |
| • | This condition may be caused by an insufficient distribution of
lubricant between the mating splines of the slider shaft. |
| • | The correction is to replace the intermediate shaft with one built
since the middle of October, 1998. Check the shaft's date code to assure it
is a good shaft. The code can be recognized by the fact that it is laser-etched,
rather than stamped on the end of the shaft. The shaft must have been built
on or later than the 280th day of 1998 (example: "282A8"). In
this example, the "282" represents the 282nd day and the final
"8" represents 1998. |
| | Important: Do not remove the intermediate shaft to examine or perform any operation
that will "stroke" the shaft. This movement of the slider joint,
past normal in-car positioning, will redistribute the grease on the shaft
and temporarily eliminate the condition. The only way to permanently repair
the vehicle is to replace the shaft if it is identified as one of the early
shafts prone to this condition.
|
A Chirping or Squeaking Sound From the Front Suspension When Hitting
Sharp Bumps (1998 Oldsmobile Intrigue)
A chirping or squeaking sound may be heard from the front suspension
when hitting a sharp bump such as a deep pothole or a speed bump.
| • | This condition may be caused by an internal misbuild of the strut.
The base valve and deflection disc may allow improper fluid flow (internal
to the strut). The unwanted flow between these two components creates the
chirping noise. |
| • | This condition was corrected on all Intrigues beginning with VIN
# XF341675 or vehicles built after January 1, 1999. |
| • | The only correction for this noise is replacement of the strut.
Struts can be checked by locating the Julian Date stamped into the strut housing
approximately 1/3rd of the way up from the bottom of the strut and facing
inward when installed. Beginning with the third digit, any date after XX8355
(8=1998 355=day) can be considered good. |
Snaps, Pops, and Creaks from the Front Struts (1998 Oldsmobile Intrigue)
Snaps or pops from the front struts during low speed turns and braking
may be the result of two possible conditions:
| • | If the Intrigue in question was built in 1997, the cause of this
condition may be due to a strut. Refer to Service Bulletin Number 73-33-04
for additional information. |
| • | The other possible cause is that the jounce bumper inside the
top of the dust boot is rubbing on the bump plate or cap. To correct this
condition, raise the vehicle and with the wheel hanging, raise each front
dust boot. Rub wheel bearing grease or other heavy grease onto the bump plate.
If the plate comes off the strut housing when the dust boot is lifted, press
it back into place firmly before greasing. This repair is so quick, this option
may be explored whenever there is a concern about steering or front end noise. |
A Vibration or Roughness in the Steering (Buick Century/Regal, Oldsmobile
Intrigue and Pontiac Grand Prix)
This is a feeling of roughness or lumpiness in the steering. This is
a subtle condition that may not be obvious like steering shudder. This condition
is typically felt during lane changes at highway speed on smooth pavement.
It is never felt when the steering wheel is turned and the vehicle is stationary.
| • | This condition is called "tire flutter" because it
originates with the tires. It tends to worsen with increased miles on the
vehicle and tires. The severity of this condition will vary with different
types of tires. Any time this type of concern is encountered, test drive the
vehicle against another Intrigue. |
| • | If the condition is significantly greater in the customer's car,
rotate the tires front to rear. This does not always correct the condition,
but it is the only known correction for this type of concern. |
Warranty Information
For vehicles repaired under warranty use:
Labor Operation
| Description
| Labor Time
|
E3858
| Strut, Front (Both) - Replace
| 1.2 hrs.
|
E7700
| Shaft, Steering Intermediate
- Replace
| 0.5 hr.
|
E9730
| Gear Assembly, Power Steering Short - Replace
| 1.3 hrs.
|
