Steps Can Be Taken to Prevent Plastic Bumpers From Fading

Question: In a recent column, you discussed problems with painted plastic bumpers on cars. My car has an unpainted black plastic bumper that has held up well, but it now seems to be fading and turning gray. What can I do to restore it?--M.M.

Answer: The fading or chalking you are observing on your black plastic bumper is the inevitable result of the breakdown of the plastic, hastened by ultraviolet rays and atmospheric pollutants.

Auto makers use many plastic formulations, all with different abilities to withstand fading. Many plastic bumpers are a composition known as ABS or acrylonitrile butadiene styrene. It’s the durable plastic that’s used in telephones and hundreds of other devices.

Parking your car in the shade should slow the aging of the bumpers, as well as preserve your paint and interior fabrics. If you live in an area with high levels of pollutants, you can expect problems.

You should not use car wax on the bumpers, because the wax will get into the pores of the plastic and then turn chalky. If you have already done that, you may want to buy a wax remover and start with a clean surface.

A number of companies produce surface treatments for plastics, the best known being Armor All. Wiping the chalky surface with Armor All will help restore the black color, but you will probably need to repeat the treatment frequently. The company claims the product will help protect the plastic from environmental damage.

Ultimately, you may want to replace the bumper if the rest of the car still looks good. An unfinished plastic bumper costs at least $150, not including labor.

Q: During the course of a work-day, I have to make many small stops of one to five minutes. Should I keep the car running or turn it off? Some friends said keeping the car running uses less gas.--J.F.

A: It’s best to shut off the engine for many reasons. Although an idling engine uses little gasoline, you will probably still save gasoline by turning it off--even for a minute or two.

More importantly, an unattended idling car can be a safety hazard. Many motorists have been injured by cars with automatic transmissions that have unexpectedly slipped into gear while idling unattended.

You also increase the risk of an auto theft by leaving the car running unattended. It would take about two seconds for a joy rider to jump into your car and drive off.

Q: I have a 1968 Ford Mustang with an eight-cylinder engine. At 120,000 miles, I had the engine rebuilt. About 4,000 miles later, the compression was down and the head was removed for more work. Since then the car has been overheating. The hoses and thermostat have been checked, but every 100 miles I need to add 1 or 2 quarts of coolant to the radiator. Is it possible something was not properly assembled or something was left out when the engine was rebuilt?--P.T.E.

A: If the overheating is the result of coolant loss, as your letter suggests, then you need to begin searching for the leak. These leaks can often be difficult to locate, but losing a quart every 100 miles is a significant loss.

You should examine the engine when it is running and immediately after shutting it off. If you can’t locate any escaping water or steam, you may have an internal leak. The water may be draining into the crankcase through a leak in the head gasket; this leak will show up when you change the oil.

One way to diagnose the problem is for a mechanic to conduct a pressure test of the system. A pressure gauge is mounted on the radiator and then the system is pressurized. That will confirm whether you have a leak.

Q: Recently the clutch pedal on my 1985 Toyota Celica GT began to squeak. Thinking it was a spring, I sprayed WD-40 on it. That didn’t work, so a mechanic discovered a noise coming from the slave cylinder (it’s a hydraulic clutch). He said lubrication would only work temporarily. Your opinion?--R.K.

A: You shouldn’t have to live with a squeak. Try a heavier-duty lubricant. WD-40 is satisfactory for a few lubrication jobs, but its role on cars is limited.

The squeak is most likely coming from the metal shaft that runs into the the slave cylinder’s rubber boot. Spread some white grease on the shaft.