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Automania/Repair & Maintenance
AUTO QUESTIONS AND ANSWERS FOR WEEK 16
by Bob Hagin
Q. I have a 1996 Plymouth Neon with just over 48,000 miles on it and it seems to run great. However, for the past 20,000 miles the brakes have been squeaking horribly, especially on very wet or moist days. I have had the brakes checked by four different repair shops and the mechanics there have all said that my brakes are good for at least another 12,000 miles. Why would they make such nasty noises if everything is OK?
A. Brake pads used on modern cars and trucks consist of palm-sized thin steel plates that have thick blocks of friction material bonded to them. There's two of them on each wheel that utilize disc brakes (in the case of your Neon, they're on the front wheels only) and they "pinch" on a metallic disc that rotates with the wheel. They work much like the brakes on a bicycle. Sometimes these metal rotors get a glaze on their surfaces and if the material on the pads is hard and built for long life, they often set up a squeak that so sharp that it can almost take the enamel off your teeth. When they're inspected, everything looks fine. The rotors aren't warped, there's plenty of material left on the pads and the stopping ability of the car is as good as ever. But the only sure cure for the brake squeal is to replace the pads with a set that's a little softer and resurface (roughen-up) or replace the rotors. It's not a cheap job and I don't think that Chrysler will pay for the job on a "squeaky-spoke" warranty, so you may want to simply turn up the radio volume until the present brake pads wear out.
Q. In October of 1998 we purchased a 1995 Cadillac Seville with the Northstar engine. The car had 40,000 miles on the odometer. After driving the car for five months and 5000 miles, I have noticed that after a long downgrade, when I return to the throttle, blue smoke (oil) comes out of the exhaust. The service manager where I bought the car said that it was typical of Cadillacs with the overhead cam Northstar engine to do that. I also have to put in a quart of oil every 1200 miles to keep the level up. I have watched other similar models on the road and don't notice any blue smoke coming out. Is the condition normal or is someone trying to pacify me until the 50,000 mile warranty runs out?
A. Blue smoke from the tail pipe on downhill deceleration (high load, maximum manifold vacuum) is usually caused by oil being sucked into the combustion chambers by leaking or weak valve stem seals or worn valve guides. Cadillac obviously isn't concerned about smoke from the tail pipe and you'd have to ask other owners if they notice the same phenomena but that would be a subjective question. A better question would be what their oil mileage would be. Auto makers are very touchy about what is considered "acceptable" miles per quart and I have a couple of service bulletins from various manufacturers that state that as little as 500 miles per quart is within their limits. I've heard of oil consumption being diminished by a change in oil brand and/or viscosity so you might give that a try. If you're taking your Cad to a dealership for service, make sure that your blue smoke/oil consumption complaint is noted on the repair order. It may be of value to you later.
Q. I have a '90 Mazda MX6 with 157,000 miles. During one of the services, it was recommended that I have the camshaft timing belt replaced along with the camshaft and crankshaft seals because the belt might "jump teeth." I plan to keep the car another couple of years so should I have these recommended jobs done?
A. At 157,000 miles, your belt and seals are overdue. Belts wear out as do seals and if the belt skips a tooth or two or breaks, it could result in monumental damage to your valves and pistons. Have the job done.
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