Question: I have a 1982 Volvo DL, which requires a 68-step servicing at 30,000 miles. The service was quoted at $350 by a dealer, but an independent garage said it could be done for $140. But that did not include replacing a $90 oxygen sensor. What's your opinion?--R.S.
Answer: The oxygen sensor must be replaced under federal law, but that doesn't mean you should be satisfied with paying $350 for a routine servicing of your car.
The oxygen sensor is part of the computerized ignition control system that is designed to optimize the performance of your Volvo. It's typical of the complicated and expensive systems that auto makers are using to meet fuel-emission standards.
The sensor is a delicate platinum and zirconium instrument that measures the amount of oxygen in the exhaust gas coming from the engine. It determines whether the engine is receiving the proper fuel/air mixture and automatically tells the engine's fuel-injection system to adjust the mixture to make it richer or leaner.
After a certain amount of use, the sensor will become coated with exhaust byproducts. If the sensor malfunctions, it will send erroneous signals to the engine, resulting in poor performance and poor fuel economy. It seems prudent to follow Volvo's advice and replace the sensor at 30,000 miles.
The sensor costs $75 to $110. So the dealer is charging about $250 for the balance of the 30,000-mile servicing, which includes a tuneup, adjustment of engine valves and an oil change. That sounds normal for dealership mechanical work. If you can find a reputable independent Volvo garage, you may be able to strike a better deal. But beware that with an independent, there is no parent corporation to hear your complaints if you are dissatisfied.
Q: Occasionally when starting my 1976 Pinto, the engine barely turns over and then cranks normally. It sometimes occurs during midday after the car has been run. The battery checks out OK, and the battery connections have been cleaned. What should I test to track down this trouble?--B.P.
A: It sounds as if you have a problem with high resistance somewhere in your starter circuit, either in the starter motor or the high-ampere wiring that runs from the battery to the starter.
A starter motor draws a huge amount of current, and all of the system's electrical connections must be solid to keep electrical resistance in the starting circuit at a minimum. Such problems sometimes don't show up until the engine compartment is hot, because higher temperatures increase electrical resistence.
First, you should check the least expensive potential problems. Have your mechanic examine the electrical connections, not only at the battery, but at the relay switch and the starter motor. Also, battery cables should be examined.
If the relay switch is working properly, then your attention should turn to the starter motor. Worn brushes will sometimes cause the motor to engage erratically. A rebuilt starter motor should solve that problem.
\o7 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. \f7