Water's Mineral Level Affects Cooling

Question: I am curious about the effect of water from different sources on the cooling system of my car. Would there be an advantage to using distilled water as opposed to city water or well water?--E.C.

Answer: Using water with a high mineral content in your cooling system could cause deposits to build up on the surfaces inside the radiator and engine, eventually inhibiting the ability of the coolant to carry away engine heat. In areas where the water is particularly "hard," radiator shops tend to have a lot of business replacing the cores of radiators that have been clogged by mineral buildup. However, the tap water in most areas is low enough in minerals that you should not have any problem. Water from a well, on the other hand, could be too hard to use in your car.

Be sure that you use a mixture of half antifreeze and half water in the radiator. The antifreeze contains chemicals designed to prevent rust and corrosion from the water and can help keep the minerals in the water from damaging the engine or radiator. You shouldn't have to use bottled water unless the water available out of a garden hose contains too much salt or other minerals.

Q: The brake pedal on my 1976 Chevrolet Caprice becomes stuck in cold weather. Hard, strong kicks to the pedal will solve the problem, but only temporarily. What could cause the brake pedal to freeze up?--S.J.S.

A: The brake system of your car has a power booster that allows you to stop the car by pressing only lightly on the brake pedal. Moisture could be condensing in the power booster and freezing in the cold weather, requiring a strong kick on the pedal to free the diaphragm that makes the power brakes work.

The power booster works by using a vacuum created by the engine to help apply pressure to the brake master cylinder when you step on the pedal. With a mechanical brake system, you have to press hard on the pedal to force the hydraulic fluid to each of the wheels and engage the brakes. But power brakes, by using the vacuum as a source of energy, require very little foot pressure.

The power booster draws air from outside of the canister to operate, so it is not a sealed system. A filter is supposed to prevent dirt or too much moisture from getting inside. Have the canister checked and replaced if necessary.

Q: I have a 1975 Volkswagen Bug with a fuel-injected engine that stalls once the engine gets warmed up. The only way to get it going again is to turn off the engine and restart the car normally. This happens many times during the day. I've had the coil, ignition switch and points replaced, but the condition persists. Any ideas?--H.J.

A: Your car has symptoms of a weak spark, and the trouble could be in the condenser or the spark-plug wires.

The condenser is an electronic capacitor, a device that temporarily collects and stores a surge of electrical current for later discharge. It is wired with the points on the car's distributor, which feeds electrical current to each of the spark plugs. If the condenser is weak, the spark may not be strong enough, and the problem can be compounded by worn or cracked spark-plug wires.

Sometimes turning the key off and on will change the polarity of the current in the spark-plug wires, allowing the car to run properly again until you turn off the engine. Have the wires and condenser replaced.

Patrick Boyle cannot answer mail personally but will respond in this column to automotive questions of general interest. Do not telephone. Write to Your Wheels, You section, The Times, Times Mirror Square, Los Angeles 90053.

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