Q-Recently, I purchased a 1994 Chevrolet S-10 pickup with a manual transmission. When I shift, the driveline clanks. This occurs in normal driving conditions. I took the vehicle to a dealership, where I was told that the noise is normal. The local Chevrolet regional office representative told me that it is characteristic for the vehicle to make the noise. The representative told me everything is OK, but they will notify me if there is a recall. That makes me suspicious. Is the noise normal? P.L.J., Bountiful, Utah
A-The driveline of many trucks make clanking noises caused by slack in the differential, transmission and drive shaft. If the manufacturer develops a cure for the noise, it’s not likely that there will be a recall unless the National Highway Traffic Safety Administration finds the annoyance is a safety concern. The carmaker could discover a cure that would be relayed to dealers in a technical bulletin or advisory. If that happens, it’s likely you wouldn’t be notified of any procedures to correct the annoyance. Stay in contact with dealer service personnel regarding that type of information. Also, you probably would pay for modifications to cure the noise unless the manufacturer develops a special policy to absorb the cost.
Q-In June, the MAF (mass air flow) sensor in my 1988 Oldsmobile Delta 88 was replaced. Since then, the accelerator has stuck as though the cruise control is on. To control the speed, I have to press the brakes so hard the car shudders. I’ve taken the car to three mechanics who don’t know what’s wrong. What’s wrong? S.P., Mendota Heights, Minn.
A-This is a dangerous situation. Take your car back to the repair facility that replaced the MAF before you loose control of it. The MAF sensor may be faulty, the cruise control may be binding or the accelerator linkage could be sticking. Get it repaired, pronto!
Q-How do I keep the fuel injectors clean? Do I have to purchase good gasoline? Can I purchase cleaners at the store and add it to the gas? Do mechanics have to disassemble the injectors periodically? J.R., Niles
A-You can buy brand-name gasoline, but that’s no guarantee that the injectors will stay clean. You may add fuel-injector cleaner to the gas tank, but it’s not necessary nor does it guarantee that the injectors will remain clean. Mechanics don’t have to periodically remove or disassemble the injectors for cleaning as preventive maintenance. Fuel injectors should last the life of the vehicle with little or no preventive maintenance. Despite this, gasoline impurities and combustion deposits may occasionally cause injectors to clog or fail. When a problem occurs, ask a technician to address it.
Q-In a recent column, you explained how much oil a car uses. Wow! I can’t imagine a car using 25,000 gallons of oil in 100,000 miles. Isn’t it more like 58.25 gallons of oil in 100,000 miles? W.W., Palos Hills
A-Mistakes happen. A do-it-yourselfer who changes the oil in his car said that after reading the column, he referred to his Popular Mechanics magazines so he could build an oil storage tank. Another reader said that I really zinged the car manufacturers. Numerous readers transmitted electronic mail suggesting various amounts of oil used by an engine. These calculations ranged from 10 to hundreds of gallons of oil in 100,000 miles. The amount of oil that an engine will consume or burn varies from car to car. Using car manufacturer estimates for oil consumption, it would be normal for an engine to burn approximately 25 gallons of oil in 100,000 miles. If you account for 3,000-mile oil and filter changes, the volume of oil used by a healthy engine in 100,000 miles would be around 60 gallons.
Q-Recently you responded to R.O.L. in Honolulu who had a stalling Dodge Caravan. You said a mechanic should check the electronic control unit. In my 1981 Mazda, the muffler was causing so much back pressure that the engine stalled. Testing the ECM doesn’t reveal this type of trouble. Can you tell R.O.L. that it could be the muffler? A.R., Gastonia, N.C.
A-You’re right. Reading trouble codes in the ECM won’t pinpoint a clogged muffler. Though, back pressure from the exhaust system could cause a sensor to malfunction. If that happens, the ECM will more than likely detect the faulty sensor. Many motorists have the misconception that the computer knows whenever something breaks though it has limited diagnostic capabilities. The electronic control module monitors only sensors and circuits connected to it. Items such as the muffler, water pump, bearings, engine connecting rods and thousands of other parts in the car aren’t monitored by the ECM.
———-
Phil Arendt is an automotive technical consultant for the AAA-Chicago Motor Club. Readers may send technical questions about cars and trucks to him at Dr. Gizmo, A+Automotive Career Counselors Inc., P.O. Box 548, Cary, Ill. 60013 or to America Online DRGIZMO.
