Dayton Daily News

Q I have a 1995 Buick Park Avenue with 58,000 miles. Recently my mechanic found evidence that there is motor oil in the brake master cylinder reservoir that turned the brake fluid into an oily sludge. He said that the fluid will deteriorate all the rubber parts in the brake system. This will cause the brakes to fail.

Presently the brakes seem to work very well. I didn't pour oil into the brake fluid reservoir, but suspect it was poured into system at a quick oil change place.

Is the brake system a goner? Will flushing the brake fluid from the system solve the problem? T.R., St. Paul, Minn.

A This is a very serious condition if, in fact, motor oil contaminated the brake fluid. Symptoms of the contamination are swollen rubber seals in the master cylinder. Also, the brake fluid becomes dark in color, sometimes black, and the fluid becomes as thick as gelatin. This could result in a sudden failure of the brake system.

Consider this. Don't drive the vehicle until this is resolved. Ask your favorite mechanic to send a sample of the fluid to a laboratory for testing to determine the state of the fluid and if it is contaminated with motor oil.

If it is not contaminated with motor oil or another fluid such as transmission fluid, there is a good chance that there isn't any serious damage to the system. A flush would be in order.

If motor oil or other product is in the fluid, all rubber parts and units that contain rubber should be replaced to prevent brake failure.

Loyal Reader Sends Tip

Q In a recent column I read about G.N. who wrote about a sticky shift lever in a 1996 Pontiac Grand Am. You were right when you thought that it was not likely that the transmission needed replacement. I have had luck fixing sticky shifters by simply cleaning the mechanism in the center console. I've found that over time dirt and spilled drinks impair the operation of the shifter. Cleaning could repair the problem.

Can you tell G.N. he may not have to spend $450 to have the trouble repaired if he cleans the shifter? B.H., St. Louis Park, Minn.

A Hopefully G.N. is reading the column today. He has an automatic transmission lever that is so tough to move that he says he nearly has to yank it out of the car.

You are correct. If he is mechanically savvy he can remove the center console trim that surrounds the shift mechanism. Once this is accomplished a thorough cleaning and lubrication may return normal function to the automatic transmission shift lever. If so his troubles may be over. If cleaning and lubrication doesn't do the trick he unfortunately may have to pay to have a failed part replaced.

Thanks for rattling my memory.

Adjustment May Cure Tapping Sound

Q At 45,000 miles my 2001 Dodge Neon with a 2.0 liter engine developed a tapping sound upon the initial start of the day. The tapping subsides as the engine warms. Now the car has 50,210 miles. The car hasn't been abused and has been serviced every 3,500 miles.

What do you think I should do? R.C., Montgomery, Ala.

A Trade it in. I'm just kidding as usual. What needs to be done all depends on the noise. If it is caused by a valve it's possible a rocker arm needs replacement, but tapping sounds can be caused by a variety of items such as a faulty spark plug wire, carbon deposits in a cylinder, a loose exhaust shield or a worn drive belt. Sometimes even a rubber bushing on the hood could make a tapping sound.

To determine the source of the noise will take some investigation. If you are handy consider purchasing a mechanics stethoscope to probe the engine and other components for the source of the noise. If indeed you verify that the noise is from the valve system it's time to replace excessively worn parts.

If the tapping is caused by a loose exhaust shield or another part address the source of the sound as needed. Depending upon your findings the concern might be solved by a simple adjustment or perhaps a dab of grease.

Air Conditioner Noise Hits High Note

Q When the air conditioner is on in a while my 2002 Volvo S80 every once in a while I hear a high pitched sound like a note from a wind instrument. I hear the sound when slowing down or when stopping for a light. Sometimes I hear the noise when I start the engine. When the air conditioner is off the noise doesn't appear.

I've been complaining about this noise for four years. I took the car to my dealer where a mechanic heard the sound one time, but he couldn't figure out where it came from. The car has been to the shop for this problem several times. Now the warranty has expired. What do you think? S.S., E-mail.

A Sounds that appear only for a short duration and are inconsistent are the most difficult to pinpoint. Since you experience the sound more than anyone, you will have to do detective work to determine the source of the sound. When it occurs try to determine where it is located. It may be behind the glove compartment. Maybe it's in the engine compartment. Try to determine the area of origin. Be as specific as possible and note all the conditions that are associated with the sound. Perhaps the air conditioner has to be set to a certain temperature or blower speed. Maybe it occurs at a certain vehicle speed. What ever you can determine will help a technician recreate conditions that cause the sound. Once you have done this, present all of your evidence to an experienced technician.

From what you describe the noise does not seem to be caused by a serious problem but is an annoyance. It may be caused by air rushing over an object in the ducts of the air conditioning system under the dash. It also could be caused by air rushing over a part in the air conditioning air intake in ducts the cowl in front of the windshield or maybe the engine air intake duct makes a sound at a certain speed. Your help will find the cause.

Oil Pressure Circuit Fault

Q My 1993 Plymouth Voyager with a 3.3 liter engine and 150,000 miles has an oil pressure issue. When I start the engine the oil pressure gauge reads 75 percent. As the engine warms the pressure drops to 25 percent. Sometimes it drops to zero and then jumps back up to 25 percent.

Does this indicate a problem with the oil pump or is there a problem with the oil pressure switch? H.S., Middletown, Ohio.

A The faulty indication likely is caused by trouble in the circuit. There likely is a fault in the oil pressure sensor, wiring or gauge. A technician likely will rule out a problem in the oil pump by connecting a test gauge to the engine. Once he has determined that the pump is functioning normally he will begin to troubleshoot the oil pressure gauge circuit. Once he has done this he likely will find that the connection to the oil pressure sensor or gauge has a fault. Repair might be as simple as tugging on the wire.

Tests Will Find Cause Of Predetonation

Q My 2000 Toyota Avalon has developed a ping sound. A dealership person told me that I should purchase premium fuel. I did but the sound continues. I returned to the dealer where I was told that there is a test they can perform but I will have to pay for the test.

Do you think I should take the car to another shop or let the dealer do the testing? S.K., E-mail.

A It's customary for dealer shops and independent repair shops to charge for tests that they perform on your car. If you went to a doctor and he decided that you needed to go through some tests he would charge you for his advice to have the tests performed and you would be charged for the tests he suggests. Then he would charge for his consultation regarding the results of the tests and charge for follow up treatment.

Once testing on your car is complete it's likely a technician might find that carbon deposits are the cause of the ping or predetonation. It's also possible he may find a faulty antiknock sensor.

If carbon deposits are to blame, removing carbon through the use of special chemicals likely will resolve your concern.

If a faulty sensor is at fault replacing the sensor likely will end your concern. Incidentally it's likely your car has two knock sensors so don't be surprised if both sensors need replacement.

Phil Arendt is a columnist, consultant and A.S.E.-Certified Master Technician. Readers may send questions to Dr. Gizmo at P.O. Box 548, Cary, IL. 60013 or e-mail address drgizmo@drgizmo.ws.