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Metal-to-metal contact may cause vibration
Dear Doctor: I have just over 13,000 miles on my 2009 Hyundai Genesis 4.6 sedan. When I first got the car it was so smooth you couldn't even feel it running. Recently, the idle has become rough when in gear to the point that after any moderate period of driving my hands are tingling. There is no vibration in any part of the car, except on the steering wheel. The dealer's tech looked it over and I was told it's not that unusual because the engine may have "loosened up" and I should live with it. Any advice? Jerry
Dear Jerry: A rough idle or vibration could be a slight engine misfire or metal-to-metal contact. The contact could be an engine mount, exhaust, or even a belt-driven pulley accessory. Some simple checks need to be done. First, disconnect the drive belt. Start the engine and observe if there is any difference. Next, using a large pry bar with the engine running and vibration present, pry the engine to either side and again note if the vibration changes. You may want to go to an independent shop for another opinion.
Dear Doctor: I'm trying to find a front left ABS sensor for my 1995 Ford Mustang. I've been told the sensor is discontinued for my model. I find it hard to believe that Ford would discontinue product (part) for a car that is 17 years old. Do you know where to locate this part? Maureen
Dear Maureen: When a part is discontinued you have a few options. The first is having the local Ford dealer do a search of any dealers that may have one in stock. Next, check auto parts stores that may carry an aftermarket brand sensor. You can also check salvage yards in your area. Also, I recommend that you remove the faulty sensor and check out a sensor for a later model, or different model, Ford vehicle. Sometimes the difference can be the length of the wire while the actual sensor is the same.
Dear Doctor: I have a 1999 Subaru Legacy Outback that has an overheating issue. The thermostat has been replaced -- initially with an aftermarket part and then with an OEM model. The water pump and belt were replaced in 2008. The radiator and temperature sensor were replaced, too. My mechanic checked for a head gasket leak twice, which showed negative both times. The car overheats after about 15 miles of driving, even at highway speeds in cold weather. Any help would be greatly appreciated. Matty
Dear Matty: I see Subaru vehicles overheat as a result of cracked cylinder heads, warped cylinder heads and/or leaking head gaskets. Sometimes the blue liquid will not change color at the radiator when performing a coolant test because the hydrocarbon level is so low when the engine is not under load. The best way to check for hydrocarbon in the cooling system is with a gas analyzer.
Dear Doctor: I have a 2002 Ford Taurus with 100,000 miles. As we pulled into a parking spot the car just died. Our mechanic could not find a problem. Then while out on a wet night it died again on me. The lights and flashers were dim. I could not get the car started and the door locks and windows would not work. I called AAA and they towed me to the mechanic. This time he changed out an oxygen sensor for $300. He changed and "flashed" the computer, but he still does not know what the problem is. Any thoughts? Cathy
Dear Cathy: I would like you to have the idle control motor and throttle position sensor replaced. A stalling problem condition such as yours is not spark or fuel related. I have come across many Ford vehicles with this issue whose computers did not have stored fault codes and fuel pressure was at specification. Ford computers are very tough and seldom fail.
Dear Doctor: I own a 2006 Chevy Cobalt. While driving a few weeks ago the engine shut down, as did everything on the dashboard, lights, radio, etc. Everything was dead. I turned off the ignition, restarted, and everything has been fine since. Nobody can tell me what's wrong. There is NHTSA bulletin 10014807, TBS 3421b, which both say 2006 Cobalt engine stall, dashboard shut down, no computer code recorded. I'm concerned from a safety standpoint. Brian
Dear Brian: Your car has multiple computers that are in constant communication with each other. If the fault happened often, then a scan tool in the movie mode could capture all computer functions and pinpoint the area of lost communication, Unfortunately, without having the problem occur in the shop it's almost impossible to find the fault.
Junior Damato is an ASE-certified Master Technician. E-mail questions to firstname.lastname@example.org