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Why is My Car Making a Howling Noise?
Howling noises are funny because the sound can be related to a minor
problem to a very major problem. The ability to differentiate between the two
variables means the difference between a minor repair or service cost to a major
replacement item such as a transmission. Howling noise can be one of the hardest
noises to detect the point of generation. If you are having a hard time
detecting the location of the howling sound, have a helper ride along in the
rear seat to give a new perspective on the origin of the howling noise. Most
grinding noises will be being generated while driving but sometimes the noise
can be heard without the car moving. Like other particular noises some howling
sounds are common among a specific manufacturer. Most howling noises are created
by a roller bearing that has failed or an air management system that has failed
or is malfunctioning. The intensity and duration can greatly vary depending on
the system malfunctioning, for example: If the howling noise is being generated
by the air injection for the exhaust system. This air
injection system can create a howling sound that is audible even though there is
no malfunction, just an undesirable noise. Some howling noises are less audible
but can be creating a large problem. Some howling noises can be progressive by
starting quietly and slowly or quickly become very loud while other
systems malfunctions can become apparent immediately. We have listed the most common problems
below:
Howling Sounds
Car Howling Noise Repair Guide:
-
Checking the Tire Wear Pattern.
A tire with a scalloped pattern on the
tire will cause a howling 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, and the suspension repair accordingly. 
Tire Wear Patterns
- Checking the IAC motor (Ford Only). IAC is an abbreviation for
Idle Air Controller. A problem that is specialized to
Ford cars and trucks is
the
IAC motor with fail causing a howling noise when the engine is running.
This noise can vary slightly as the engine is subject to load. The IAC can
still control the engine idle or not. To check for this condition can be
difficult, first remove the IAC and inspect the plunger inside the valve. If
any of the plastic coils are broken or missing replace the IAC, that's an
easy find but sometimes broken pieces are tough to see but replacement is
still required.
Ford Idle Air Controller
- Checking the Air Injection Pump and System. An air
injection pump is used to pump air into the exhaust system to help complete
the combustion process after the
exhaust charge as left the
combustion
chamber. The added air promotes the charge to continue burning to expend any
additional fuel that was not burned. The air pump also helps the
catalytic
converter arrive at operating temperature by adding air which in turn
creates heat to the catalyst material. Much like a fire, and what happens to
it when the fire is fanned with addition air, the fire gets hotter. On
vehicles equipped with an air injection system the air
pump can create a howling sound that will start and stop during
engine
operation. The air injection system is equipped with one or two check valves
that allow air to transfer into the exhaust system. If one or both of these
valves fails it can cause the air pump to labor creating the howling noise.
To check for this condition remove the check valves also called diverter
valves and blow through them both ways, the valve should only allow the air
to pass through in one direction. If the valve allows air to pass in two
directions the valve has failed and needs replacement.
Electric Air Pump
- 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 howling 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 lubricating inside
of the bearings.
Axle Bearing/Race Set with Seals
Check Main Differential Gears: The main
differential gears transfer power that is delivered from the
transmission to the wheels. These differential gears can become misaligned
because of a failed carrier or pinion bearing and they will disintegrate and fail. While this
condition is occurring it will make a howling or grumbling sound. The only way
to confirm this condition is to disassemble and inspect the bearings and bearing
races. If you remove the oil fill drain plug and remove a small sample of oil
from the carrier, hold it up to the light and inspect for small metal particles.
If metal partials are detected further repair is required.
Failed Ring Gear Pattern
- 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 howling sound. 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. 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.
Power Steering Cap
HOWLING NOISE CONTINUED-->>
For manufacturer specific procedures for any of the steps above please visit
our car repair
manual page.
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