Shakes, Rattles, Squeaks and Thunks...(Smells and Noises)

For the uninformed, identifying where that squeak or thunk is coming from on your car or truck, or determining where that pungent odour is coming from, can be quite disconcerting. However, being cognizant of usual noises and smells emanating from your vehicle will help you nip potential automotive problems in the bud. Early detection of strange sounds or smells coming from your vehicle can help reduce repair costs, and if you are like me, everyone hates to pay those exorbitant fees charged by automotive repair shops these days, right?

Here are some tips to help you identify some of those early tell tale signs, just by using your nose and ears. A very common sound is brake squeal. On domestic vehicles brake squealers are used. These are little pieces of wire that touch the brake rotor when the brakes are applied. Those are designed to alert you the driver, that there is very little brake pad material left, and that it's time to replace the pads.

On import vehicles, if you experience brake squeal, it may be dust particles or sharp edges on the surface of the pads rubbing on the rotor. The only way to be sure is to remove the wheel where the offending sound is coming from. The brake pads then need to be removed and checked to see if there are dirt particles or sharp edges on the surface of the pads. Most of the time this has been the primary cause of brake squeal on these vehicles. It can happen if the vehicle is either hot or cold. Inferior brake pad material can definitely add to the brake noise list. Another problem that can happen is experiencing grinding noises when you apply the brakes. When you get grinding noises you have to be very careful, because that is a sure sign that the brake pads or brake shoes have worn down to bare metal. When your brakes are applied you have the metal of the brake pads or brake shoes contacting the brake rotors or brake drums, and that requires an immediate repair.

Other grinding noises coming from your car might be from faulty or worn wheel bearings. Wheel bearing noises are more of a roaring or groaning sound. On most cars, whether front-wheel or rear-wheel drive, that sound would come from the front of the car. To determine which wheel bearing is the culprit, drive the car at approximately 30 mph/50 kph on a quiet road, and for example, if you round a left hand corner, the centrifugal force results in the load being applied to the right wheel. If the grinding is exaggerated, then the wheel bearings on the right side need to be checked to see if there is movement or play in the wheel. Perhaps all that is needed is for the nut to be tightened holding the wheel bearing assembly in place. If the bearing is worn, it will have to be replaced. Conversely, if the grinding noise occurs when the vehicle is negotiating a right hand turn in the road, then the left side (driver's side) wheel bearing will have to be inspected.

The most common sound is that of a blown muffler or leaking exhaust. Most people recognize that sound. But one sound that is quite difficult to diagnose, even from an automotive technician's perspective, is when one experiences a ticking sound coming from the engine compartment. If the ticking sound is experienced on a cold morning, most likely it can be attributed to an exhaust manifold gasket leaking. This noise may be misinterpreted as valve tappet noise. The exhaust manifold gasket leaking noise is the result of the contraction of the cast iron metal of the exhaust manifold and the cast aluminum head on the engine, leaving a tiny gap at the gasket, which allows for the exhaust gases to leak through. In most cases, if the leak is detected within a year, the cure is simply to tighten the manifold bolts. If the gasket is punctured or the problem has persisted for over a year, the gasket will have to be replaced and the manifold assembly machined, due to distortion.

Rumbling sounds coming from the engine compartment may mean that the cooling fan is not in balance and is vibrating, or there may be a worn water pump. The latter would result in a grinding sound similar to wheel bearing noise. A very tight fan belt will exert a load on the water pump impeller and cause the noise to be quite loud. A fan belt adjustment may all that is required to alleviate this problem. If the water pump is leaking anti-freeze, then the only alternative is to replace the unit. Fan belt squeal, experienced when the engine is revving, can be rectified by tightening the fan belt. There are many more noises that can be identified by the average motorist, from a faulty heater fan, power steering pump, air conditioning unit, etc. Unfortunately, these repairs are beyond the scope of the average car owner and best left to a qualified automotive technician.

What are some of the most common automotive smells that can be identified by the vehicle owner? A very common smell is that of burning engine oil. Leaking valve cover gaskets will cause the oil to drip onto the exhaust manifold, resulting in a pungent smell. Usually there is some detectable smoke associated with that as well, which will cause the eyes to water. Tightening the valve cover bolts or nuts may be all that is required, however, in many cases the valve cover gasket will have to be replaced.

Anti-freeze smell is a very sweet smell and is usually detected inside the vehicle. This is usually due to a heater core that is leaking. A green damp spot on the front passenger side carpet or mat is usually evidence of the leak. Unfortunately, this idicates that the heater core, which is similar to a radiator, will have to be replaced.

Electrical smells are very strong, and is a sure sign that something is burning. The plastic insulation around the wires usually melts first and in extreme cases can catch fire. This problem is generally a result of an electrical circuit shorting out in the car. It could be the starter motor shorting out, or the alternator burning out. That odour will enter the vents into the passenger compartment of the vehicle. It will be evident and often obvious where this type of smell is coming from. It emits a smell similar to burning rubber. A starter motor that is jammed in the flywheel will try to keep on spinning until the engine is stopped. That is burning insulation and the temperature on the starter motor can reach several hundred degrees.

Fuel smells can be nauseating. A fuel smell will be a raw smell, similar to the smell you experience when taking off your gas cap when you fill up at the service station. This is usually the result of a leak in the fuel tank, fuel filter, carburetor/fuel injection system or a fuel line in the engine compartment. Most motorists can readily detect fuel smells.

An exhaust leaking smell which is caused by a leaking catalytic converter or leaking exhaust system can be a choking odour that can burn your eyes. If your car has open heater vents or if there is a panel that is rusted or cracked to allow the gases to enter the passenger compartment, which acts like a vacuum, especially if you open your car's windows, then carbon monoxide will enter the vehicle. We are all aware that carbon monoxide in a closed environment can kill you. Exhaust problems should be repaired by a qualified automotive technician as soon as they are detected.

If your car or truck is running a rich fuel mixture, the exhaust emission will smell like fuel. When a vehicle runs rich, it means that raw fuel entering the combustion chamber does not burn completely, and raw fuel comes out of the exhaust.

Finally, automatic transmission fluid smells, particularly with larger vehicles, are a very common problem. When the oil seal is leaking at the rear of the automatic transmission, the torque converter at the front, or seals on the selector shaft will leak oil that falls on the exhaust pipe near the rear of the vehicle. That smell, similar to that of burning engine oil, is a strong odour, but slightly different, will enter the passenger compartment.

Determining the unusual smells and sounds you are experiencing with your vehicle will be of immense help to the mechanic or automotive service technician you decide to take your car or truck to. Today, with increasingly sophisticated cars and trucks, a simple method of pinpointing the problem are will not only give your mechanic or automotive technician a welcome head start in solving your problem, but it will invariably translate into real savings for you. And really, why not use our two investigative senses of smell and hearing? They don't cost us anything to use, do they?

Gordon H. Ficke is a Photojournalist specializing in vintage and classic vehicle historical features, automotive tips for the lay motorist and educational travel articles. Samples of his work can be viewed on his website:

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