A car makes sounds when driving, but sometimes, this accompaniment becomes too loud and unusual. It can be a roar or a growl. What should you check in this case? The mechanics from the Indy Auto Man car dealership in Indianapolis reveal the malfunctions that can provoke frightening sounds.
Problems with the exhaust system
Perhaps this is the most common malfunction that creates a sound when you press the gas pedal. A loud rumble accompanies removing gases from the engine by default. An entire exhaust system with different components works to reduce its level. Since it is under the bottom of the car, constantly heating up and cooling down (which attracts condensation), its parts can rust through to holes. And then the exhaust makes a sound every time you press the gas pedal.
A hole can appear in any part of the system: pipe, resonator, or muffler. But there are other reasons. Sometimes, the protective casing or corrugation (flexible adapter) rots away.
Finding the source is easy – you need to start the car, put it on a pit, or hang it on a lift, and listen carefully to where the sound is coming from. The hole may give itself away by a black halo of soot around it. If some parts are damaged, it is possible to put on a patch. But if the part is badly rusted, it needs to be replaced.
Deformation of the crankcase protection
Profile metal sheets often protect the crankcase. They are quite strong, but when in contact with a curb or an obstacle on the off-road, they can bend and rest against the crankcase itself. There will be a few inches between the two parts, and when the engine is running, they will touch with a noticeable metallic rattle. A similar sound occurs if something hard gets between the crankcase and the guard, such as a stone.
The diagnostic principle is the same as in the previous point – start the car and look from below. Another indirect sign is increased vibrations of the body when idle. If you suspect the guard, you can simply unscrew it and try to rev it up or drive on a flat road.
Combustion problems
Sometimes, the reason for the engine to roar or even “shoot” when you press the gas is the so-called triple. Normal fuel combustion stops in one of the cylinders, for example, when the spark plug fails on a gasoline engine. Unburned fuel gets on the hot elements of the exhaust system and burns with a micro-explosion. This explosion is the cause of loud sounds when the engine is running.
It is not difficult to determine the triple: usually, the engine starts to work intermittently and vibrate. You can try to refuel the car with known good gasoline, but if nothing changes, it is better to go to the service for diagnostics.
Wear of engine parts
Perhaps this is the most unpleasant reason since its elimination often costs a tidy sum. Many parts of the engine can make sounds of different natures – from clicking to howling. For example, when the connecting rod or main bearings of the crankshaft wear out, a loud rumble occurs, and it is difficult to confuse it with any other sound in the car. The problems are not always fatal – for example, a stretched timing chain or a tensioner that has stopped working can also cause abnormal sounds.
If you do not understand the structure of the car engine very well but hear that the sounds are coming from it, it is time to go to the service station.
Incorrect use of transmission
In some cases, incorrect selection of the automatic transmission mode can cause increased noise while driving. Drivers sometimes turn on the sport mode, and then the gearbox starts to shift noticeably later. The revs increase before shifting – and the noise of the engine increases.
The second possible scenario is again the accidental activation of manual mode (or a mode with a limitation of the upper range). In it, the automatic transmission will allow the engine to spin up to the cutoff, which will also cause an abnormal roar at speed.
And if you have a manual transmission and the engine roars, but the car accelerates poorly – the problem is most likely in the worn clutch. It simply slips, unable to transmit torque and engine speed to the wheels.
Summing up
- Before starting diagnostics, make sure you have chosen the correct transmission mode.
- Most often, a growling sound during acceleration is a sign of a burnt-out part of the exhaust system.
- Another reason is damage to the crankcase protection or a stone getting between it and the crankcase.
- Some sound sources are tricky: for example, those coming from the engine. It is worth visiting a service station if you have doubts and can’t fix the problem right away.