By Jim Kerr
They say that "Love makes the world go round", but in reality, it is bearings that enable everything in the world to turn. From the discs in your computer hard drive to the motors in a supertanker ship, it is bearings that create the low rolling friction so that parts can turn rapidly. There are hundreds of bearings used in an automobile. Some need maintenance and others just need to be inspected occasionally.
Trailers too, roll on bearings too and need to be part of our regular vehicle maintenance schedule.
There are several types of bearings used on a vehicle. Some are called bushings, which can be a brass or bronze material that supports a spinning shaft. Small electric motors may use bushings made from aluminum or plastic. These types of bearings require no maintenance, but if they start to "squeal" or make noise, then sometimes they can be lubricated with light grease or oil. Older heater motors sometimes squeal when started in cold weather, and lubricating them can make them last much longer. Many times however, the components are sealed or it costs more to disassemble them to lubricate them than a new replacement part is worth. Your best route is to change the part if it gives problems.
Engines use bearings to support crankshafts and camshafts. Crankshaft bearings are a type of bushing with several layers of material on them. A strong back layer provides support. A softer inner layer forms the actual bearing surface, while a very soft top layer holds small dirt particles so they don't damage rotating parts. Camshaft bearings may be made the same way but many of them are simply holes bored in the aluminum cylinder head material. The only way engine bearings can last is to separate them and the shafts that run inside them with a thin layer of oil. Without a layer of oil, there would be metal to metal contact and the bearing would quickly fail. That's why oil pressure is important in engines.
So is clean oil: forget to change your oil at scheduled intervals and there will be acids and small dirt particles circulating with the oil. This can wear engine parts. The oil filter will trap larger particles, but small particles can pass through. Clean engine oil will protect your engine from premature wear.
Wheel bearings used to be a routine maintenance item. Every season, the bearings from the non-drive wheels would be removed from the vehicle, washed, inspected, repacked with grease and reassembled. These bearings contain "pencil diameter" rollers that support the rotating parts while enabling them to turn freely. Today, most vehicles use sealed bearings on all wheels, so routine maintenance is no longer done, but there are still some vehicles such as pickup trucks, boat and camper trailers that do have serviceable wheel bearings. They need to be maintained every year. Many of the trailer breakdowns you see at the side of the road are due to wheel bearings that have failed due to a lack of maintenance.
When a wheel bearing starts to fail on an automobile, you will usually be given lots of warning, if you are listening to your vehicle. It usually starts by a very slight and low-pitched vibration in the vehicle. As the bearing gets worse, the noise might turn to a rumble. The noise will be louder when turning a corner one way and quieter when turning the other way. This is because the poor bearing gets louder when a load is placed on it during cornering.
Winter roads mask a lot of vehicle vibrations and noise, but now that spring has arrived, driving your vehicle on a smooth stretch of road while carefully listening to your vehicle can detect a bearing problem. Don't assume a service shop would find this type of problem unless it is really bad. You know your vehicle, what types of sounds it makes and the normal vibrations inside it. When something changes, you are in a better position to identify that a change has occurred than someone unfamiliar with your vehicle. A change in vibrations or noise may indicate that a bearing is beginning to fail, and it is much better to find a problem when you are near home than when you are stranded halfway to your holiday destination.
Jim Kerr is a master automotive mechanic and teaches automotive technology. He has been writing automotive articles for fifteen years for newspapers and magazines in Canada and the United States, and is a member of the Automotive Journalist's Association of Canada (AJAC).
