Automania/Repair & Maintenance

AUTO QUESTIONS AND ANSWERS FOR WEEK 48

by Bob Hagin

Q. A long time ago we would turn on our headlights during the daytime when we were traveling on the highway. We would do it to keep from doing damage to something in the electrical system. When I travel now in my car I see many cars coming at me with their headlights on in the daytime even though they are not driving in a "Turn Your Lights On" area. Is there something beneficial to a car or to the engine by driving with the lights on or is it strictly a safety feature? W.W. Chowchilla, CA

A. Leaving your headlights on to protect the car's electrical system is really old stuff. My dad did it to protect the electrical system on his '36 Ford to keep the generator from overcharging and burning up the battery and the wiring system. Those early voltage regulators weren't always up to the job and by turning on the lights, some of the current was drained off. Fortunately, auto charging systems haven't had these kinds of electrical problems since World War II (at least none that I can remember) and now the reason you see cars and trucks with their lights on is that it's easier to identify them when they're on the road, even in daytime. Many new cars such as the VW and the Volvo have built-in systems that automatically turn on the lights and keep them on while the car is in operation and some people without these automatic systems drive with their headlights on for safety. My wife is one of them. The main problem with using this technique is that it's easy to leave the lights on when parking since its not obvious that they're still burning. Some vehicles have a buzzer that signals if the lights are still on when the engine is shut off but in the case of my wife's Toyota, the lights go off when she stops the engine and opens the door.

Q. Our 1990 Mitsubishi Mirage has a four cylinder engine, a standard shift has many miles on it, about 120,000. Our son used it when he was going to college and drove it on the highway a lot going to and from school. Now he has graduated and gotten a newer and larger car and we only use it around town for grocery shopping and such. Since we took it over, we find that it hesitates and stumbles when it's started up and it doesn't seem to have the power it had when it was new. The garage where we have the car serviced wants to take off the cylinder head and grind the valves although the engine runs quite smoothly when it's warmed up. T.H. Tucson, AZ

A. Before you have the engine pulled down, have your mechanic run some fuel injector cleaner through the injectors. It's relatively inexpensive and may help a lot. Another problem may be heavy carbon build-up on the intake valves which can be cured by either removing the head and grinding the valves or blasting off the deposits. This technique uses a power-system that blows ground-up walnut husks into the intake system to knock off the deposits.

Q. I've had several occurrences of having the battery go dead when my 1984 Toyota van is parked overnight. It has to be parked outside and when the battery went dead the first few times, I assumed that I had left something on. The battery isn't very old so I'm pretty sure that it's OK. After I jump-started it, I took it to a service station but the mechanic couldn't find a problem. H.L. Salt Lake City, UT

A. You should have the charging system checked thoroughly for output under a full load (headlights, a/c, etc.) but better give the battery a close check first. If it has removable cell caps, have a mechanic use a hydrometer to check the specific gravity of each cell. If one of them is even ten points lower than the rest, it could be causing the problem as you describe it. An even quicker test is to use a load-tester. This device puts a load on the batter and if the voltage drops below 10 volts after a few seconds, the battery is weak.