Skip to content

Hear a knock, smell burning rubber, feel a shake?

When it comes to cars, regular maintenance is key to good health. But there may come a time when you see, hear or feel something that may indicate a problem.

When it comes to cars, regular maintenance is key to good health.

But there may come a time when you see, hear or feel something that may indicate a problem.

We asked mechanic Mo Taheri, of Dundarave Automotive Repair Centre in West Vancouver, to diagnose a few common symptoms.

Symptom: Smelling burning oil, exhaust, or gasolinePossible diagnosis: Valve cover gasketsA bad smell is not necessarily bad for the car, but it's likely unpleasant for the driver, says Taheri. But a burning smell should always be checked out, he Taheri recounts how a driver recently dropped off an older model car at the shop noting she could smell gasoline. Examining underneath the car, it was discovered that the metal gas tank had rusted and had to be replaced. Taheri says this is an example of a smell that indicated a problem that could potentially have been dangerous since it was causing a large leak.

Symptom: Smelling a sweet smellPossible diagnosis: A sweet smell can be from the exhaust. A blown or worn-out gasket can let antifreeze inside the engine where it will burn.

Symptom: Vibration Possible diagnosis: A vibration could be related to tire balance or separated tires.

When tires gets old, the rubber and steel inside can get worn out and the tire can bulge.

"It gives you a really massive shake on the highway or just normal driving it gives a lot of shakes," says Taheri.

If you feel the vibration when the car increases in speed that could be balancing. There are wheel weights that go on the side of the tire rims and over time the glue that holds them in place may wear and the weights could fall off. That might cause a vibration.

Wear on the tire could also cause a vibration.

"If you're feeling vibration you better have it checked out because when you get a vibration it could actually damage the tire," says Taheri. If a vibration can be felt when you press on the brakes, that could be worn discs, he adds.

Symptom: PullingPossible diagnosis: Pulling can be related to alignment.

Alignment angles can wear out if you hit a curb or just with time. It could also be caused by a faulty tire.

Symptom: ShakingIf you feel a heavy shake in the brake pedal and/or with steering, you should get it checked because if you have to stop and the car shakes too much you might get scared and cause an accident, says Taheri.

Symptom: RattlingRattling can be caused by a loose exhaust shield. The exhaust shield is supposed to keep the heat from the body of the car but can come loose due to rust.

Usually it gets clamped down again and is not a difficult problem to fix. It is also not necessarily something that has to get fixed but the noise might bother some drivers.

Symptom: Hearing some knockingPossible diagnosis: If a tire has a flat spot it could make a noise but you would feel the vibration in the car, says Taheri.

A knocking noise could also be from the engine if you put the wrong gas in the car, he adds. If the car calls for 91 octane, for example, and you put 87 octane in there it could cause knocking on higher rpms, notes Taheri.

Higher end cars should use what the manufacturer recommends. High-performance engines usually take higher octane.

If you use a higher octane in a car that calls for a lower octane, it doesn't do any harm but it doesn't help it in any way, explains Taheri.

But if you put lower octane in a car that calls for a higher octane it might cause some damage.

Two things to always get checked out: A gas smell and grinding "Any sort of grinding in the car, that's not a good thing," says Taheri. He explains that grinding could indicate some damage has already happened to the car, so it might get worse if left untreated.

Rosalind Duane,