Question: I recently replaced my windshield wipers with a new set of blades. During the first rain, I discovered the new blades were chattering across the windshield. Why aren't the new blades operating properly?--K.T.
Answer: Chatter is usually caused by old windshield wipers in which the rubber blades have become stiff and inflexible. Usually this happens as the blades on a car are exposed over the years to heat and sunlight. But blades can deteriorate in storage as well.
If the auto-parts store where you purchased the blades has a low turnover, chances are that the blades may have been sitting around for many months. Worse yet, many gas stations store their blades outdoors in metal display boxes, which turn into virtual ovens under the sun.
Another important measure to optimize the performance of wipers is to have a clean windshield. Chatter can be caused by a thin, almost invisible film that develops on windshields as a result of such things as pollution and tree drippings.
Often enough, such films are resistant to many glass cleaners. Acetone can remove most films, but exercise extreme caution in using it because it can severely damage automobile paint. Another possible remedy, according to one backyard mechanic, is to rub used coffee grounds on your windshield.
Q: I have a 1980 Buick Century that has a stalling problem. When starting the car in the morning, the motor dies as soon as I put my foot on the gas pedal. After a few miles, the condition disappears. Why is this happening?--J.I.S.
A: In years past, a cold-engine stalling condition almost always related to choke adjustment, but the addition of emission controls has added many other potential sources of stalling. On your model car, the problems can relate to such systems as the choke, the vacuum temperature switch, the vacuum controller on the choke or the exhaust-gas-recirculation valve.
The function of the choke is to give an engine more gas when it is cold. The 1980 Buick Century has a choke that opens with the heating action of an electrical element, which sometimes malfunctions and needs replacement.
Your mechanic may also want to check a switch that routes exhaust gas back through the engine. When the engine is cold, the valve should be closed because recirculating exhaust into a cold engine will cause stalling. The valve must sense engine temperature correctly to prevent stalling.
Finally, your car also has a so-called vacuum brake on the choke, which prevents it from closing entirely and flooding the engine. If the vacuum supply or function of the switch is impaired, the engine will receive either too much or too little gas, which will result in stalling.
Q: I have a 1982 Honda Accord, which has a great repair record. But it has one problem that my garage has been unable to correct. If I stop the engine for about 15 minutes after it has reached normal operating temperature, the car jerks, sputters and surges when I resume driving. What causes this?--T.C.
A: A number of Honda Accord owners have complained of this problem. It is caused by high temperatures that develop under the hood when the motor is stopped. The high temperature causes "percolation" in which gas inside the carburetor boils and floods the engine. Honda issued a service bulletin in 1982 advising installation of a special kit that automatically turns on the engine fan to cool the motor in certain conditions after it is stopped. Dealers have the option of installing the kit free of charge.
Ralph Vartabedian 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.