Question: I have a 1983 Nissan Sentra Wagon, which needs strut shock absorbers badly. The only place I can find them is at the high-priced dealer. Does anybody else make shocks for this very popular car?--L.B.
Answer: Your problem is typical of many owners of aging Japanese cars with McPherson-strut front suspensions, which can cost an arm and a leg to service.
While everybody has been heralding the great "improvement" that McPherson suspensions provide motorists, they obviously weren't considering the cost of getting some of these front ends fixed when the shocks went out.
A McPherson suspension is usually found on front-wheel-drive compacts and subcompacts. It combines an integrated coil spring, shock absorber, spindle and ball joint, thereby eliminating a lot of parts on the traditional front end.
On some McPherson-strut front ends, you can simply install a new shock-absorber cartridge into the strut assembly, but on many others, including yours, you have to replace the entire strut.
Nissan lists the cost of the strut for your car at $129 per side, and you must replace both sides for a total cost of $258. Plan to spend an additional $100 for labor. And that's just the front end.
In my opinion, that's an outrageous charge for such a minor repair. It used to be the case that you could replace all four shock absorbers on a car for less than $50. I've actually heard of cases where people have been quoted $500 for replacement of all four struts on newer cars.
If you shop around, however, you can possibly get a better price. Monroe, a respected name in shock absorbers, has recently begun producing a replacement strut for your Sentra. I was quoted a price by one tire dealer of $69.95 for the strut and $22 for installation per side. That's about $200, but it's a lot less than Nissan's price.
Q: Even gentle grades cause my 1986 Toyota Camry with its electronically controlled spark advance to ping. The timing is correctly set, though. My wife's 1985 with a vacuum advance does not ping. Is my car's behavior typical, and is it harmful?--R.M.W.
A: It seems as though the improvement of going to an electronic spark advance hasn't done much for the Camry, at least with respect to engine knock or ping.
On most older cars, the timing of the spark plugs was controlled partly by a vacuum device that sensed how much load was on the engine. When accelerating or going up a hill, the vacuum increases, which causes a vacuum-controlled plunger to increase the spark advance. The newer cars have gone to an electronic sensor system.
It's unlikely that the problem you are observing will damage the engine. Ping is caused by the uncontrolled detonation of gasoline inside the engine. A higher-octane gas, which resists the tendency to burn in an uncontrolled fashion, would help eliminate the noise. But I don't think it is a necessary expense.
Some ping is normal when going up a hill. As long as it doesn't continue more than five seconds or so, it is not an indication of a malfunction.
Here's an update on a question I handled recently on whether to keep a clutch engaged or disengaged while waiting at a traffic stoplight. If you can be prepared to move with traffic when a light changes, it is better to wait with the transmission in neutral and the clutch pedal up. Holding a clutch pedal down during a long light will definitely increase the wear on a clutch throw-out bearing and cause a very minor amount of wear on the clutch disc. But don't wait until the last minute to shift into gear and then quickly pop the clutch to get going. That's worse than sitting at a light with the clutch disengaged the whole time.