Q. I run an auto-repair facility in Concord (Calif.). We specialize in electrical system repairs and diagnosis. Your article about the wipers was great until you recommended the used part. I feel that those parts should be used only when all other sources have been exhausted.

Used parts are not only that, but we do not know when putting them on if they operate, so if the one being installed has the same problem as the part you took off you would be directed to guess at the next most likely part.

There are ways to recycle other than using used parts, such as remanufactured or rebuilt parts. The problem with used parts is they do not last as long as quality replacement parts.

Hans Hiller,

Concord, Calif.

A. Hans, you’ve brought up several good points that deserve a closer look. Most, if not all, repair shops are leery, to say the least, of installing used parts on their customers’ vehicles. A used part often comes with no guarantee of performance, and should it fail, the labor to renew it a second time can generate hard feelings (the customer buys the time) or lost productivity (the shop eats the labor).

You also are correct about the possibility of a replacement used part having the same problem as the original (a pattern failure), which could result in further guessing of the cause of the fault.

I leaned this way on Alice’s car for a couple of reasons. Wiper motors are virtually indestructible and are often very simple to change. Only a crazy person would gamble many hours of precious time on a fix that carries more than minimal risk of failure. I also assumed – perhaps falsely – that she might find a friend or family member to install it, rather than a repair shop. Removing a used part from a vehicle at a self-service auto recycler is a pretty low-risk way to learn how things fit together. If you should break a trim clip or connector latch, better on that car than your own.

As one who also takes pride in fixing things right the first time, I appreciate your concern for customer satisfaction and value. Many times there just isn’t space to explain things the way I should.

Q. How often should spark plug wires be replaced? Mine look great but are 15 years old.

Pete Fuller,

Sunnyvale, Calif.

A. Spark plug wires perform a tough job, delivering many thousand volts to the spark plugs.

The two most common faults are insulation damage (abrasion, oil soaking, or leak-through) and terminal corrosion (at either end – look inside the protective boots).

If your wires are free of visual flaws and have less than 25,000 ohms resistance (measured with a volt-ohm meter end to end), they should be fine.

If the engine cuts out or stumbles, or the wires look/test less than perfect, replacement is a good idea.
Brad Bergholdt teaches automotive technology at Evergreen Valley College in San Jose, Calif.

E-mail him at under-the-hoodjuno.com or write to him in care of Drive, Mercury News, 750 Ridder Park Drive, San Jose, Calif. 95190. He cannot make personal replies.)
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AP-NY-04-02-04 0620EST