Dear Doctor: I own a 2000 Hyundai Elantra. It has started to idle rough and is sluggish starting from a stop. Then the “check engine” light came on. I went to the dealer and they said the transmission was starting out in third gear and had an emission purge valve problem. What do you think? Phil
Dear Phil: The dealer is on track with the diagnosis. You can try shifting the transmission manually — and if this method is OK with you, then you’ll save a lot of money. The emission purge valve can cause a rough idle by causing either a lean or rich condition. Is the car worth a transmission replacement? That is up to you.
Dear Doctor: I own a 2001 Ford F-150 Lighting 5.4-liter supercharged V-8 with 40,000 miles. Recently, I was checking the air filter and found some oil in the inlet attached to the supercharger. I cleaned the oil and rechecked it one week later and found a very small amount of oil again. I replaced the PCV and checked the vacuum. My mechanic said the oil is not draining fast enough back into the oil pan. The engine runs great and there is no sign of a problem. What are your thoughts? Eric
Dear Eric: The design of the intake system does allow some oil to puddle in the bottom of the air filter housing. I have replaced the factory air intake system with aftermarket fresh air systems and the oil problem has gone away. There are many power upgrades that will make a big difference. A supercharger pulley change and computer reprogramming are the two improvements that I would recommend you do.
Dear Doctor: I purchased a 1981 Mercedes-Benz 380 SLC with some front end damage and only 39,000 miles. I had the damage repaired. The only problem now is the transmission slips when up shifting into the next gear. If I let up on the gas pedal just before it up shifts, then it feels fine. I had the transmission fluid and filter changed, but I still have the same problem. The shop said the transmission will need an overhaul at a cost of $2,500. Is there anything else I can do? Jay
Dear Jay: The first step is to make sure the transmission throttle pressure rod is connected from the throttle body to the transmission. If everything checks out, then the next thing is to try changing all the transmission fluid, using type F transmission fluid. Type F is a transmission fluid that will not allow as much slipping. We use type F in high performance cars. This was a fluid used in Ford products in the years before the development of all the electronic transmissions.
Dear Doctor: I own a 2004 Nissan Maxima with 66,000 miles. When the brakes are applied there is a loud pulsating and rotational thumping sound. A technician said a sensor is applying the anti-lock brakes system, but there are no fault codes. We a puzzled. What are your thoughts? Gerry
Dear Gerry: Common failures in the ABS are rusted and broken axle tone rings. I have seen a lot of warped brake rotors cause this condition.
Dear Doctor: I have a 1998 Oldsmobile Intrigue with a headlight problem. During the day the daytime running lights work as they should, but at night only one headlight works. Can you tell what’s wrong? Mike
Dear Mike: The first step is to check the low headlight bulbs. Most daytime running lights work off a low voltage on the high beam bulb. Other late model cars use a separate bulb. Some vehicles also have fuses for both left and right headlights.
Dear Doctor: I own a 1996 Dodge Caravan that has a problem with the seat belts not locking when stopping quickly. I asked the dealer and they said the seat belt assemblies may need replacement. I asked my mechanic to replace them. He replaced the belts, but they only locked once on a quick stop at 30 mph. What do you think? Vinny
Dear Vinny: I believe you are talking about the seat belt tensioner locks. These seat belt locks operate with a swinging pangolin. When the stop force movement is forceful enough the pangolin locks the small gear on the seat belt retractor. There needs to be a great sudden force to activate the locking mechanism.
Dear Doctor: My son is interested in automotive training and considering enrolling in one of the advertised trade schools. Is there another option? Rick
Dear Rick: Be very careful on a school selection. I have found that some claims do not add up. I have a technical senior student working at my shop now and he graduates in May. He went to a few schools and was disappointed. His choice now is to stay with us and learn as he goes. Another option is to work at a car dealership where they send you to an automaker’s factory school.
Junior Damato is an ASE-certified Master Technician.
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Copyright, Motor Matters, 2009