Dayton Daily News

Q: Lately my 1996 Chrysler Cirrus with 112,000 miles has been stalling when coming to a stoplight or sign. A mechanic checked out everything and tells me that the computer needs replacement. His estimate is $600. What are my options? A.S., e-mail

A: If the technician did a thorough job of testing and found the computer has a fault, it is likely the proper diagnosis. It is, however, possible that he did not properly diagnose the trouble. It is possible that the terminals in the plug that connects to the computer are suffering from corrosion. This could cause test equipment to determine that the computer is faulty when it is not. Cleaning the terminals may be the fix. Ask him to consider this. Also, you could go to another repair shop for a second opinion.

Contaminated gas tank

Q: Last April I purchased a 2004 Mazda 3 with an automatic transmission. In June, the car began to have a starting problem. After I fill the gas tank, the engine is difficult to start. I have to crank the engine for as long as 4 minutes. Once the engine starts, there isn’t a problem until the next time I fill up the tank. When this problem began, the check engine light turned on. I took the car to two different repairs shops where I was told a computer code indicated a large emissions leak. The system was thoroughly checked, but no leaks were found. I was told that the gas cap was not properly closed, but it is. At home I have removed the gas cap and attempted to start the engine. It starts fine. Someone told me that perhaps there is trash in the gas tank. What’s your advice? S.C., e-mail

A: Evaporative emission leaks are leaks in the fuel system. Small or large leaks allow fuel gasoline vapors to escape into the atmosphere. This triggers the check engine light. There are small leaks that can develop from failing solenoids, valves, seals and hoses in the evaporative system. In your case, testing determined a large leak — likely from the gas cap. Since you don’t run the engine while fueling the car, this should not be the problem. It is possible that the gas cap is not as tight as it should be or there is a problem with the cap. A replacement might cure this trouble. Also, the idea that there is contamination in the fuel tank is not a far-fetched theory. It is possible that when you fill the tank, you stir contamination in the bottom of the tank. There is a filter in the gas tank that helps to prevent contamination from entering the remainder of the fuel system. When you turn on the ignition, the fuel pump energizes and whatever is in the gas tank can adhere to the filter and impair fuel flow to the engine. Test the theory. The next time you fill the gas tank, don’t start the engine right away. Wait five minutes. If the gas tank is contaminated, whatever is in the tank may quickly settle to the bottom. If so, the engine may start without trouble. If contamination is the cause, the fuel tank should be removed for a thorough cleaning.

Total blackout

Q: In the past 20 years I have been driving nothing but Lincoln Town Cars. Presently I’m driving a 1997 Lincoln Town Car with 139,000 miles. It runs like a top. The only problem is that when I turn on the high beam headlights within five minutes the lights go out. All the running lights, dash lights and headlights turn off. It isn’t long before the lights turn back on but this has caused some frightening moments. So far I haven’t had an accident. I’ve taken the car to two garages. A dealer mechanic left the car out all day with the high beam lights on and nothing happened. A local independent garage mechanic replaced the dimmer switch. This didn’t cure the trouble. How many other Lincoln owners have had this problem? M.F.B., White Bear Lake, Minn.

A: No other Lincoln owners have written Dr. Gizmo with this problem. A check of factory technical service bulletins and recalls did not find documents or a repair pattern relating to this kind of impairment. Consider logging on to the National Highway Traffic Safety Administration’s web site. They have all kinds of information regarding vehicle problems. You may discover that other Lincoln owners have reported a problem such as yours to the government. The web address is www.nhtsa.gov. As for fixing the trouble, perhaps a technician should consider replacing the headlight switch. It’s also possible there is a loose connection in the engine compartment or at the power distribution center. Perhaps a circuit breaker has a fault.

Brake system redundancy

Q: Years ago cars were outfitted with dual brake master cylinders. This helped to prevent accidents caused by a failure of the hydraulic system. Do you have any knowledge of where, when and why these dual master cylinders were discontinued? N., e-mail

A: They weren’t discontinued. The master cylinder has two chambers. One chamber is for two wheels and the second chamber is for the other set of wheels. If one part of the master cylinder fails only the brakes at two wheels are impaired while braking is accomplished at the other two wheels. Depending upon the year, make and model car the chambers in the master cylinder may be split so that if one chamber of the master cylinder fails braking is accomplished by one front wheel and one rear wheel. Some cars are designed so that if one chamber fails either the front or rear brakes stop the car.

Clunking sound needs investigation

Q: There is an odd clunking sound coming from the front of my 2005 Chevrolet Impala. It feels as though something is loose in the steering. This typically occurs at lower speeds. This is my first front wheel drive car. Is this something normal or is it something I should return to the dealer to have them check? G.H., Becker, Minn.

A: Clunking noises are not normal for front wheel drive vehicles. What you experience might be caused by something loose in the front-end. Also, there are a few factory technical service bulletins that address various noises from the steering system. Return to the dealer to have this condition diagnosed. You certainly don’t want to drive the vehicle if something in the steering is loose. Repair all depends upon the type of sound, where it is and the cause.