Saturday, August 23, 2008

good motoring
Risks of driving in the rain
H.Kishie Singh

Water can do an incredible amount of damage to your car. Common sense and good road etiquette demand that you drive slow and carefully when roads are waterlogged. Chandigarh has experienced some heavy downpours in recent days. It was not uncommon to see cars speeding through knee-deep water. It may be fun driving through water, splashing it all around. But it is not the right thing to do. Pedestrians, cyclists and scooterists are in danger and can meet with an accident. As it is, the roads are under water and lead to skidding. Two-wheelers are vulnerable but four-wheelers skid just as easily.

The danger lies under the water. Potholes have become big and deep. They can damage the suspension easily. Open manholes can cause extreme damage. Wet brakes become quite ineffective. As a result, the breaking distance increases.

One of the most extreme cases of water damage is a seized engine. Sounds strange but it does happen. The air cleaner is designed to suck in air and feed it to the carburettor or fuel injectors. Then there is a combination of fuel and air mix, and it is sucked into the combustion chamber of the cylinder.

This is the induction stroke—the first movement of a four-stroke engine. The inlet valve is open to suck in the mixture of air and fuel. In the compression stroke, the second movement of the piston, the inlet and exhaust valve are closed. The piston moves up and compresses the mixture of fuel and air. The heat generated vaporises the mixture.

In the third stroke again, both the valves are closed. The spark plugs fire the mixture and cause an explosion, which drive the piston down. The piston is connected to the connecting rod, which, in turn, is connected to the crank shaft. As the piston moves down, it rotates the crank.

The final move of the engine is the exhaust stroke. The inlet valve is closed, the exhaust valve is open. As the piston rises, it expels the burnt gases. The four-stroke cycle is complete. Back to the induction, and the cycle restarts.

Now let us see what happens when water enters the air cleaner. During the induction stroke, the piston moving down sucks in water. The second stroke, compression, begins. Both inlet and exhaust valve are closed and the water is trapped. The piston cannot compress the water but the con-rod (connecting rod) and crank keep moving. Some thing has got to give. The piston cannot move but the crank shaft is still pushing. Result? The con-rod bends. Engine seizes. It will stop.

The technical term for this is hydro-lock. So far you may have damaged only one con-rod. However, if you try and re-start the engine by cranking, the engine water may enter the other cylinders and cause more damage. There is only one recourse open to you. Switch off and call helpline for your car.

Happy motoring !