Globe and Mail: Your car is trying to tell you something

It is surprising how little some people know about the information displayed on the instrument panel of their vehicle. The Budds’ Service team felt that it may be a great idea to post such an article for those of us who have no idea what that little yellow light in the middle of our dash is trying to tell us.

While it may seem superfluous, every gauge or light has a story to tell and in virtually every case failure to listen to that tale can have disastrous and expensive repercussions.

Let’s get the obvious ones out of the way first — speedometer and fuel level. No need for explanation here.

Next up in order of significance — the oil pressure gauge or light. Oil is literally the lifeblood or fluid that keeps an engine alive. Not only does it provide the lubrication that allows metal pieces to rub together without damage, it acts as a coolant, drawing heat away from these high-stress locations.

The oil is circulated and squirted in critical areas under pressure, provided by a pump. If the pressure drops, the oil is no longer able to provide its vital lubrication role and the various components will very quickly heat up to dangerous levels where they may seize.

This quickly becomes engine failure — very expensive engine failure. Not only will the vehicle come to a complete stop, it won’t move again until you have lubricated the repair shop with thousands of dollars.

The temperature gauge, whether a dial marked with a range from “c” for cold to “h” for hot, or a warning light, provides another critical piece of information.

The temperature gauge does not tell you the temperature of the engine — directly. It shows the temperature of the fluid flowing through the engine.

This fluid carries heat away from the engine to the radiator where it is cooled by the air flowing through it. It then continues its circuitous route back into the engine, lubricating pumps and things on the way.

When the engine is first started after sitting for a period of time, the fluid is at ambient or outside temperature. A thermostat prevents the fluid from going through the radiator until it reaches operating temperature. Until that point, it simply circulates through the engine gaining heat as the big block of metal is heated by the combustion of fuel within the cylinders. As this happens, the temperature gauge will gradually move off the cold mark.

Until that fluid is warm, no heat can be drawn off it for the “heater,” which warms up the interior. When the fluid reaches the proper temperature, the thermostat opens, allowing it to flow through the radiator and monitors that process, opening and closing as necessary to keep the fluid within the proper temperature range.

If the thermostat should fail, or the level of fluid gets too low, the temperature will escalate and the gauge or a warning light will warn of pending problems. If you fail to heed that warning and the engine is allowed to overheat, it can cause catastrophic failure.

The voltmeter or battery gauge tells us of the condition of the electrical circuit. As the engine draws power form the battery for everything from the spark plugs to the power windows, that power has to be replaced — the battery has to be recharged.

There is a whole system of doing this we won’t get into here, but the driver should most definitely check this gauge to ensure the recharging is taking place.

If a belt were to fail or other problem occur that slowed or stopped the recharging process, the instrument will provide the necessary warning, allowing enough time to safely locate service.

The tachometer tells us the speed of the engine — as opposed to the speedometer, which provides vehicle speed information.

The tachometer is commonly marked in single digits ranging from 1 to 7-10. That is in multiples of one thousand so if the needle is on “5″ the engine is turning over or operating at 5,000 revolutions per minute or rpm.

The tachometer is useful for telling the driver when to shift gears. If the vehicle has an automatic transmission, it is not as important. The important factor with relation to the tachometer is to avoid overrevving the engine.

RICHARD RUSSELL
From Thursday’s Globe and Mail