Car Repair Advice by Professional Automotive Experts
Car Noises /
Vibration Noise
Why is My Car Making a Vibration Noise
Introduction
Vibrations are annoying and can be difficult to detect the origin of the
generating member. Vibration sounds are different from other related noises
because vibration noises can travel a distance from the actual cause, for
example: If an engine mount has failed allowing the engine to contact the car
frame it can sound like the vibration noise is being created near the middle or
rear of the car. Or if the rear car tires have devolved a cupping condition it
can sound like the vibration noise is being generated from the whole car. This
transference of vibration noise is called telescoping. If it is not clear where
the vibration noise is being generated from it helps to turn your head from side
to side while taking note on which ear is hearing noise. This technique is
helpful when troubleshooting the origin of the noise. Vibration noises can be
generated by almost any part of the car because most components are subject to
rotating parts. If your car is vibrating because the engine is misfiring please
visit
why is my engine misfiring? We have list common; engine running with car not moving
and car in
motion problems below:
Vibration Noise
Car Repair Guide - READ COMPLETELY BEFORE BEGINNING!
Engine Running, Car Not Moving: This section includes
symptoms that present themselves when the engine is running only.
- Check Engine Mounts: Engine mounts are used to minimize
engine vibration by isolating the
engine from the car frame. These mounts are constructed by using rubber
vulcanized between to metal plates with threaded studs that bolt to the
engine and the frame of the car. When motor mounts become worn they allow
the engine the contact the frame causing a noticeable vibration. Inspect the engine
mounts for integrity, look for any oil, cracks or separation
of the mount. Remove the failed engine mount and replace if needed. For
exact instructions how to replace the engine mounts in your vehicle consult an
auto repair
manual.
New Engine Mount (appearance will vary)
-
Vibration Noise When Air Conditioner is On - The
air
conditioner is designed to operate using a electromagnetic clutch
assembly that receives a command signal from the activation switch. This
command controls when electricity is supplied to the compressor clutch that
engages and disengages the air conditioner system. If the air conditioner
expansion valve/office tube is plugged or the system has excessive oil or
refrigerant it can cause the system to vibrated when activated. To check for
this condition the system will need to be drained and refilled to proper
specifications.
-
Inspect Harmonic Balancer: The
harmonic balancer on your engine is used to help silence engine
vibration by utilizing a rubber mounting metal ring attached to a hub that
is connected to the front of the engine. If this ring becomes dislodged
because the rubber insulator has failed it will allow the outer ring to
bounce on the rotating hub. This condition will produce a
vibration noise that will change with engine speed. To check for this
condition
remove the multi rib belt and check the harmonic balancer condition. If
the outer ring is lose replacement is required.
Failed Harmonic Balancer
-
Checking Flex plate Balance Weight (automatic transmissions only):
The flex plate on the rear of your engine is designed for three
reasons, first it connects the engine to the torque converter of the
transmission, next it allows the starter to engage and crank the engine over
and finally it contains balance weights that help the engine stay in balance
when operating. These counter balance weights are spot welded onto the flex
plate. If these weights become dislodged it will cause the engine to
vibrate. To check for this condition remove the flywheel cover. Using a
flashlight inspect the weight location, also there could be signs were the
weight was thrown off of the flex plate while the engine was running. (Note:
not all cars have a weighted flex plate)
Weighted Flex Plate
Car Moving: This section includes symptoms that present
themselves when the car is in motion
-
Checking the Tire Wear Pattern.
A tire with a scalloped pattern on the
tire will cause a
vibration sound at speeds over about 45 MPH. This tire condition is caused by a
combination of worn struts or shocks and or tire imbalance. If a tire is not
being controlled evenly the tire will vibrate causing the tread to contact the
ground inconsistently. This inconsistent contact with the road causes the tires
tread to wear unevenly. (Cupping, tire example on the right). To check for this
condition, take your hand and pass it over the tire tread, it should be smooth.
If high and low points exist the tire is cupped and needs to be rotated or
replaced depending on the severity of the cupping condition. 
Tire Wear Patterns
-
Checking Axle Bearing Failure: An axle bearing is designed to support
the weight of the vehicle while allowing the wheels to rotate. These
bearings are manufactured with high grade steel that resists wear under
extreme conditions. When an axle bearing fails it allows metal to contact
metal under pressure with a linear motion creating a vibration noise. Once an
axle bearing fails it cannot be repair, replacement is required. Remove axle
bearing and replace with new and recheck. Some vehicles are equipped with a
bearing hub assembly. The bearing below is the style of bearing is replaced
by un-bolting the bearing hub assembly and replacing it with new.
Axle Bearing Hub
Other bearing designs include separated bearings that include inner and
outer bearings with bearing races, a four piece set. Separated bearings
require an inboard seal attached to the bearing hub. This seal rides on the
spindle to hold grease inside of the bearing hub, keeping lubrication inside
of the bearings.
Axle Bearing/Race Set with Seals
-
Drive Shaft U Joints. A driveshaft U joint is designed to act as a
rotating junction that can be flexible while still transferring energy from the
engine to the
rear differential. A universal joint or U joint is constructed of 4 bearing
caps that house multiple needle bearings. The universal joint is lubricated by
adding grease through a zirk fitting on the joint. Some u joints are
manufactured with a proper amount of grease and do not need service and
therefore do not have a service fitting. If a universal joint fails it can make
a vibration noise that contours the motion of the car. To check for this
condition inspect the U joint and look for a light rust powder around the
bearing cups. This rust colored powder is caused by metal disintegrating and is
a sign of universal joint failure. When a universal joint has failed it must be
replaced and cannot be repaired.
Universal or "U" Joint
-
Automatic Transmission Fluid: An automatic
transmission functions by automatically changing the gear ratios while
determining the speed and load of the engine. A torque converter utilizes
transmission fluid as a coupling agent allowing the engine to run while the
car is stopped without stalling the engine, then re-engaging to make the car
move again once the RPM of the engine has increased. If the transmission is
low on fluid due to a leak or service it can cause the transmission to
vibrate. If the transmission is vibrating the first thing to do is inspect
the transmission fluid level and condition of the fluid. If the fluid level
is ok try servicing the transmission. If the condition continues the
transmission could need replacement or rebuilding.
Locate and Remove the Transmission Fluid Level Indicator
- Testing Check Front Drive Axle CV Joints: When CV joints start to
wear they will bind up on acceleration and in
tight turns. This causes a vibration in the
front suspension that transfers to the vehicle. Remove drive axles and inspect
flexibility of each CV joint. If a bind or hard spot is observed the CV
Joint/Axle needs to be replaced.
Front Wheel Drive Axle
-
Checking Power Steering: A
power steering system is designed to utilize power from the engine
to assist in the force needed to steer the vehicle. When the engine is running, a
multi ribbed
serpentine belt is used to transfer engine power to a hydraulic fluid pump. This
pump pressurizes fluid and then transfers this fluid using power steering hoses
that are connected to a power steering box or rack and pinion depending on how the
car is designed. When the power steering system has run low on fluid it can
create a vibration. This noise is more apparent when steering the car.
When the power steering is malfunctioning the vehicle will
be very difficult to steer. It is advised not to move a vehicle with the
power steering system not operating properly. Any steering component malfunction can
cause the vehicle to be uncontrollable. When a malfunction occurs check the
system fluid level and add as needed. When this condition occurs the
power
steering system has a leak and needs to be inspected and repaired. If
the system fluid level is in the normal range and the problem persists the
steering rack or pump might need replacing.
Power Steering Cap
-
Check for Front Brake Rotor Run Out: Front
brake rotors can warp when in heavy use. This is caused by extreme heat created
by friction and pressure applied to the front brake pads and rotors. A heavy braking
condition can be caused by driving down a long grade or extreme driving conditions
such as racing. When a brake rotor becomes warped it will cause the steering wheel to
vibrate when
the brakes are applied. To inspect for this problem rotate the brake rotor by
hand. The brake rotor should move freely, but with some resistance and turn for
360 degrees without hard spots. If the brake rotors are warped it is recommended
to replace them. It is possible, but not recommended to re-machine to the rotor
(the rotor will
be straight but it will have less mass to dissipate heat therefore re-warping
is eminent).
Front Brake Rotor, Brake Pad and Brake Caliper
For exact specific repair procedures for any of the steps above visit
our
car repair
manual page.
Car Noises /
Vibration Noise
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