Question: I have a 1984 Thunderbird with a six-cylinder engine. It has idled fast since about 2,000 miles. It now has 15,000 miles on it. By fast, I mean I travel 40 miles per hour without putting my foot on the gas. I have been to two garages four times. Do you have any suggestions?--D.A.
Answer: The procedure for setting the idle on a Ford Thunderbird is very exacting, and any deviation will result in problems. I think your problem has been with some poorly informed mechanics.
The engine should idle at about 525 revolutions per minute with the automatic transmission in drive. A decal under the hood lists the proper idle speed. If your car is traveling at 40 m.p.h. at idle, it is obviously badly out of adjustment.
To set the idle speed, a mechanic first must disconnect a very small, computer-controlled electric motor that directs a number of carburetor functions. For example, the small motor takes the place of the carburetor "dashpod," which prevents abrupt drops in engine speed.
After retracting the electric motor's plunger, a mechanic can set the base idle speed by adjusting a screw on the carburetor. The next step is to set an air gap between the plunger and the motor at exactly .28125 inch.
Q: At about 2,300 miles, my Mercury Cougar with V-6 developed an annoying squeak in the engine. After a couple of false starts, including replacing the thermactor pump, the dealership decided to replace all of the rocker arms. They have ordered them but now the squeak has disappeared. What caused the squeak? Should I have the rocker arms replaced anyway while the car is still under warranty?--N.H.B.
A: A lack of lubrication could have caused damage to the rocker arms, which resemble small teeter-totters that open and close the engine valves.
A blockage in the tiny oil passages inside the engine block may have stopped lubrication to the rocker arms and the shaft that holds them in place.
The squeaking would stop if the blockage has cleared, but the rocker arms could still be damaged. If the dealership has diagnosed the problem as rocker arms and agreed to replace them, I strongly suggest you follow up on their offer. It is an expensive job that you will not want to face once your warranty expires.
Q: I have a 1979 Toyota Corolla. For some time now after I have driven it for an hour or so, it will not restart. I have to wait about 30 minutes. The solenoid clicks but does not engage the starter. The Toyota dealership cannot find any problem. The battery tested out fine. Have you ever experienced anything like this?--P.W.
A: The problem is most likely the result of a poor electrical connection or a defective solenoid.
Heat raises electrical resistance. If the resistance is too high, not enough current will reach the starter motor to turn over the engine.
You should check the two primary ground wires and the positive cable from the battery to the starter. The contacts on the wires should be clean and free of corrosion.
If the wires are clean, your problem may be in the solenoid, which is a magnetic switch inside the starter. It may be corroded or arched, preventing good electrical contact. It can be replaced without replacing the entire starter motor.
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.