Question: My 1983 Toyota Tercel has performed great over the last 65,000 miles, but recently it has developed a whining noise that comes from the rear end. The car has always had a lot of road noise, but this is different. It developed just about the same time I purchased new tires. The tire dealer claims that the noise is normal for certain types of tire tread, but it's really louder than anything I have ever heard.--L.N.V.
Answer: The source of your problem is unlikely to be tire and road noise. Although variations in the design of tire tread sometimes cause a humming noise, your problem is probably caused by worn-out wheel bearings.
If the wheel bearings are badly worn, they may have excessive play. A mechanic can easily check for that by jacking up the rear end.
Even if the bearings don't have excessive play, they may be ruined because they did not receive proper lubrication. Toyota advises its car owners to have the rear bearings repacked in grease every 30,000 miles. Unfortunately, it's a job that some mechanics don't perform. Replacing the bearings on one wheel will cost about $50.
Incidentally, I have heard that some owners of noisy subcompact hatchbacks have been able to substantially quiet their cars by lining the spare-tire wheel well with fiberglass batting, which is available at hardware stores. Usually, low-price compacts have almost no sound insulation in this area.
Q: I have heard that a company somewhere is selling lead that consumers can add to their gasoline for older cars. Is that true and where can I buy it?--D.V.
A: Tetra-ethyl-lead, the substance in leaded gasoline, is currently available for motorists in certain states, but not California.
While it is illegal for retailers to sell bulk gasoline containing high concentrations of lead, consumers in some states may add their own lead. California, however, specifically prohibits motorists from adding their own lead to gasoline.
In addition to legal consideration, many industrial companies have been reluctant to sell full-strength lead to consumers because of the toxicity of the substance. As little as one drop of 50%-strength tetra-ethyl-lead on the skin can lead to poisoning.
As an alternative, many retailers are selling a lead substitute, using sodium as an active ingredient. These products, under such names as Sim-U-Lead and Lead Substitute, are sold at auto-parts stores.
Q: My 1981 Ford Mustang has a problem with its "fast-idle" cam on the carburetor sticking. I have had it fixed in the past, but it continues to reoccur. When it does stick, the engine idle speed shoots up to between 1,800 and 2,000 revolutions per minute. What is the permanent fix for this?
A: The fast-idle mechanism is part of the carburetor choke and is designed to make the engine run slightly faster when the engine is cold. As the car warms up, the fast-idle cam slows and allows the engine idle speed to move back down to the normal range of 600 to 800 rpms.
The problem could be caused by the choke itself, which controls the fast-idle cam. The choke may be stuck and may not open after the car is warmed up. Your mechanic can inspect for that by looking down the carburetor.
If the choke is opening, possibly the cam mechanism is simply dirty. If it is, spray choke cleaner (available at most auto-parts stores) on the parts.
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.