Why your car makes a rattling noise

Thursday June 13 2019

If you suspect any unusual noise or rattling,

If you suspect any unusual noise or rattling, take your car to a mechanic for further investigation. File photo 

By Roland D. Nasasira

No motorist likes driving a car that makes unusual noise. While that attracts attention to your car especially when it can be heard by other motorists, rattling noises point to underlying mechanical conditions that require immediate attention.

Old engine mounting
John Aturinde drives a Toyota Nadia. When he starts the engine, the engine mounting, which, is also technically known as the motor mount, produces rattling sounds. They are almost similar to vibrations. When he accelerates, the rattling sounds intensify. At a high speed, the sounds tend to disappear but resurface when the speed reduces.
“When I went to the garage, the mechanic said the car’s engine mounting had worn out and could not hold the engine firmly. It, therefore, needed replacing,” Aturinde says.

While Aturinde needs to part with approximately Shs400,000 to have his engine mounting replaced Robert Kabuye, a mechanic at Vine Garage in Kisaasi, notes that the cost of replacing an engine mounting depends on its make and size. This is because engine mountings that are used in saloon cars cannot be used in sport utility vehicles such as the Toyota Land Cruiser TX and vice versa.

According to Kabuye, some of the signs of a failing engine mounting include strong engine vibrations and loud noises. The noise can be heard when you start the engine but the vibrations can also be felt when holding the steering wheel.
“When your engine vibrates, it means the engine mounting that plays the role of keeping the engine in one position without shaking or losing its initial position is old. It means the engine is stronger than the engine mounting,” he says.

Loose exhaust system
Jimmy Ssebadduka, a mechanic at Shell Jinja Road, notes that rattling noises in your car could be a sign of a loose component of your car exhaust system. When cars with low ground clearance get in contact with the road surface, especially humps, the part that rubs against the ground is the exhaust system.
“When you drive over humps many times, the nuts that firmly hold the exhaust system in one position become loose. In the end, you will hear noises as you drive, especially when going up the hill,” Ssebadduka notes. This, he explains, is the reason you drive behind a car and you are able to see a bigger part of the exhaust pipe.

Old water pump
The primary role of the water pump is to pump coolant from the radiator to all parts of the engine to keep it cool.
This flow should, however, be constant as long as the car is in motion. Ssebadduka advises that when your water pump is ageing, it will supply coolant inconsistently and this will in most cases result into high temperatures in the car engine.
“When you open your car bonnet and the radiator is producing a cloud of steam and the engine is hotter than usual, it means the water pump is old and needs to be replaced, immediately. If you do not replace, it will create more damage to the engine pistons and the cylinder head,” Ssebadduka warns.


Low transmission fluid level
Moses Mugisha, a mechanic in Ndeeba, says without automatic transmission fluid, it becomes hard for you to engage gears and reduce the speed of a car in high speed by downshifting. The fluid plays an important role of lubricating these parts. Downshifting is the process of controlling the speed of your car, say from 150kms per hour to a lesser speed or when a car can no longer move at all.
“When your transmission fluid levels into the tank, you will have to use a lot of force and energy to engage gears. The gearstick tends to become stiff and hard. As you engage gears, it will produce a grinding sound, which is a sign of low transmission fluids,” Mugisha explains. He advises that when you check the user manual, all cars have recommended limits of transmission fluid below and above which you are not supposed to drive your car, and this should be moderately maintained.

Heat shields
According to Carfromjapan, an online portal, heat shields are components that act as a thermo-reflective barrier between the exhaust system and other parts including the gas tank, fuel lines, and the cabin of a car.
When they are loose or broken, they fail to completely block the heat transfer to these key areas. As a result, you will hear frightening rattles at higher speeds.
The portal advises that you have to inspect the exhaust system to find out if heat shields are causing rattling noise in the car when accelerating. However, do it only when the engine is off for several hours. The exhaust pipe and some other parts remain hot even after hours of switching the engine off.

Identifying the noise
If you hear rattling somewhere in the dashboard, then it is probably something in the glovebox or various compartments inside. Take away everything from these and drive around for a quick test.
If the dashboard is vibrating, try pushing it in different places while driving. If the noise stops, then you have found the cause.

If the rattle comes from below when you are driving on a bumpy road or cornering a bit hard, then it is most likely the suspension. Nothing to worry about, it could be as simple as anti-roll bar links which you can readily replace yourself. If the rattling is not constant, wait with the repair until it is. It will be easier to identify what is wrong anyway. But if you have problems with steering or the suspension is unstable, check that out immediately.