This past summer, Bob Leone worked at a General
Motor’s (GM) new-car dealership, which “turned out to be
a ‘front line experience’ even for an old hand like myself,”
says Bob. Although, technically, he was the dealership driveability
tech, Bob says that “anything electrical also made its way
toward my stall.”
This article on interior noise was inspired
by Bob’s summer experiences.
With GM’s new slogan, “People in Motion,”
comes a tremendous amount of product gadgetry that’s designed
to capture the hearts and minds of the folks who drive these vehicles.
The mileage the company gains from such a slogan means very little,
however, if the fancy gadgets work but “rattle, tick, clang”
and generally torment vehicle owners until they’re insane.
Techs working on the new GM entries from Buick,
Pontiac and GMC can foster customer appreciation – and restore
sanity – by knowing a little about how to fix a “clank, clank,
clank!” sound (or any other annoying, incessant noise) that
can result after a collision.
The best way to approach a noise problem is
to ask the customer specific questions about the nature of the
complaint and then verify the answers with a test drive. But,
only about 50 percent of the complaints are readily identifiable
by the vehicle operator, meaning the other half are determined
through diagnostic adventure.
Diagnosing Interior Problems
Begin chasing a complaint by determining if
the source comes from the interior or exterior. If it’s interior,
listen to the noise with reference to the materials involved.
For example, the following are some interior
noises, their causes and their solutions:
- ITCHhh … itch … itch … – Plastic corners rubbing
together can cause an itching noise to emanate from the instrument
panel. Cold weather causes the plastic components to offer a greater
reflex toward ordinary small shifts in fastener grip, resulting
in cyclic noise that can cause problems.
Door panel to instrument board corners is one of the biggest offenders.
By removing the function or switch plate on the door and loosening
the front armrest screw on most full-size models, you should be
able to apply pressure to the door panel in a rearward direction.
The slotted screw holes will allow about 2 or 3 mm of adjustment,
which will usually quiet things down. Summer heat and an enclosed
car might call for more adjustment later on, so keep this in mind
and don’t use adhesive products to keep things in place.
GM has a service bulletin (December 1993, reference 201601) on
other panel-related rattles. Use this bulletin – even on late
models – if you’re still having trouble with noise within the
- Tick … tick … tick … – Ticking in the
windshield outer frame area can be eliminated by removing glass
stops that are vestigial and used during assembly on ’93-’95 GM
cars. Removing the cowl and digging the offenders out with a pair
of needle nose or “stork” type pliers will solve a noise
problem that seems to be coming from beneath the instrument board.
- BUZZzzzzz … Chirp! – Looking for a “buzz”
or a “chirp” on these cars should start with a look
at the panel cover. Do a once over on the screws holding things
in position, but look more closely for distortion from the sun
and poor reassembly techniques. If the panel was untouched during
the collision and the fitting is out of position with the mounting
holes, the customer may qualify for warranty service, depending
on time/mileage coverage.
- Rat-tat-tattle … tap, tap, tap … – S.R.S components
are frequently disturbed when any service is performed at a dealer
or other facility because it’s always necessary to find and disconnect
two-way connectors under the lower panel pass through. If these
connectors aren’t repositioned into their clip holders after reconnection,
tapping noise or light rhythmic rattling may occur. Also, look
over the knee bolster to see if the foam rubber strip is in position
or has moved up and over, causing contact with the lower panel
to create a scrubbing noise.
- Rasp, rasp … – If the hush panel insulator rubs its
support stud, you may hear a rasping sound, which can be eliminated
by loosening things up and moving them forward as far as possible.
- [email protected]!#*! [email protected]#!* – One rattle – which sounds like
baseballs loose in a metal box – can be found by grasping the
center instrument-panel support and pushing sideways to eliminate
the rattle and isolate the component. A permanent fix involves
pulling down the glove box and reaching behind to the left to
tighten the outer support screws. And don’t forget to adjust the
glove box door and/or the latch if you’ve disturbed their position
or you’ll get another rattle.
- Noise, noise, noise! – The radio fax plate on Pontiacs
and Buicks can create a noise problem if clips are factory installed
with less than desired tension. GM recommends changing out the
radio under warranty. Another way to silence the noise is with
a two-part clear epoxy, which will dry quickly and won’t mat the
performance of the unit.
- BUZZzzz … !!!!!!! – The HVAC control assembly can
buzz incessantly if the alignment pin is not on center with the
rear of the unit. Wrap a chunk of foam around the rear of the
unit to stop this bothersome buzzing.
Door Panel Noises
Because solving door-panel noises is a favorite of mine, I’ve
included a few door-panel tips and tricks:
- Door panels with new actuators for the locks might need to
have linkage rebent for clearance.
- Door motor replacements have problems with window roller positioning
and/or old parts, rivet spines and other debris left over in the
door from the repair.
- All Christmas tree fasteners should be replaced whenever door
panels are pulled off.
- Door speakers can rattle like the dickens if the self-tappers
that hold them on have lost their torque. Go up a size or use
a recessed head screw with a nut and washer inside to silence
this problem. Ditto for switch panel or trim pads that may have
screws that have been in and out too many times.
- If you’ve found a panel that’s broken through at a screw attachment
point, you may have to replace the panel to quiet things down.
Plastic welding will be effective only in a few cases because
of the beating the panel might take in ordinary service. Quoting
the panel now will save your buying it the second time around
when the car comes back with a noise.
Power-seat noise is the next biggest interior complaint. Before
hunting, though, check with GM to see if it has any recall campaign
in effect for track and mount replacement. Many GM techs says
they’re doing these by the dozen lately, and the job may be under
warranty even if the vehicle is off regular time/mileage coverage.
- If you’re stuck with a loose track, the fix will be to replace
the track assembly. The ’97-’98s have a lot of room to reach the
seat bolts, and a high-power, quarter-inch drive ratchet setup
will cut your time to almost nothing. Some of the early units
require that plates and shrouding be removed, so consult the shop
manual for this.
- Some ’93 Buicks suffer from a squeak from the rear window
pillar that’s caused by the omission of an epoxy strip beneath
the sail panel closeout (the squeak may or may not show up after
a collision has knocked things around a bit). Installing three
screws in the overlap area should solve the problem.
- Many GMC S-series trucks make an annoying sound when the seat-access
lever cable has been installed incorrectly. Symptoms include a
complaint of no seat movement in the quick-release position and
a rattle that’s sometimes worse with the seat all the way forward.
To be rid of this rattle, replace the seat cable, and check the
track-locking pawls to see if they’re bent. Replace worn or broken
parts and the overstressed cable, and reinstall the lever correctly.
Peace and Quiet
Collisions are bad enough for those involved, but to be left with
an annoying noise after the repair can be just as bad –
an incessant sound can test the patience of even the calmest vehicle
owner and push a high-strung driver right over the edge. Ridding
owners of aggravating clangs, ticks, taps, rattles, squeaks
and creaks will not only restore peace and quiet, but also
a customer’s peace of mind.
Writer Bob Leone, a retired shop owner, is ASE Three-Way Master
Certified and is completing qualifications as a post-secondary
automotive instructor in the vocational school system in Missouri.