Q. My car stinks when I turn on the heater. Do you have any idea what this could be?

A. The most common cause is mold and mildew buildup in the heater ducts. Short of professional cleaning, you could try liberally spraying Lysol or a similar product into the air ducts. This may kill the mold. The other less desirable possibility is a rodent could have gotten into the car and died.

Q. I have a 2001 Jeep Grand Cherokee, and it has been using antifreeze. I have checked all the hoses, and the local shop has pressure tested the cooling system but didn’t find any leaks. The car needs enough antifreeze to turn on the low coolant light every few days. What is wrong?

A. A pressure test will locate some leaks but isn’t particularly effective with looking for internal coolant leaks such as cylinder head-gaskets and cracked cylinder heads. I have found the best method is to use an infrared exhaust gas analyzer. This is simple, quick and accurate. Simply warm up the engine and hold the end of the exhaust gas analyzer over the top of the open radiator. If there are combustion gases in the cooling system (indicating an internal leak), it will register as a hydrocarbon reading. The other method is to use a combustion-leak test kit. These kits use a special liquid that turns color in the presence of combustion gases. These test kits are accurate and can be purchased for under $50. Also, one item not to over look is something as simple as a faulty radiator cap.

Q. My old, but generally dependable, 1997 Ford Taurus has recently had problems starting. After I turn the ignition, it takes 20 to 30 seconds before it starts. I’m concerned that before long it won't start at all. What should I do?

A. Have a repair shop perform a diagnostic inspection, focusing on the fuel system and other engine controls. The Ford Taurus has been known to have problems with the idle air control motor, as well as the fuel pump. This is just two of many possibilities. You should leave the car with a quality repair shop overnight so they can experience the problem.

Q. I took my Ford truck to a well-known repair shop for service. They had the truck for the day and did an engine tune-up. The truck seems to run a bit better, but it still has a starting problem. I am very disappointed. What should I do?

A. In all but very few cases, a tune-up doesn’t fix anything. Tune-ups are performed as preventive maintenance. I think your truck didn’t get repaired because of a communication problem. I would return to the shop and explain the truck’s starting problem in detail. Giving the repair shop as much information as possible will get your truck repaired correctly.

Q. Lately, my 2008 Buick LaCrosse (still under warranty) makes a little noise when I start it. It sounds like noisy valves in a 30 year-old car. The noise does go away after a couple of minutes. I use the recommended 5w-30 oil. Is this normal or am I hurting the engine?

A. Many engines today make a bit of noise on start up. The noise may be a result of “piston slap.” As the engine warms up, the pistons expand and the noise quiets. Your best bet would be to leave the car overnight at the dealer so they can hear and document the noise. Having documentation of the noise would be helpful if a problem is discovered outside of the warranty period.