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Automania/Repair & Maintenance
AUTO QUESTIONS AND ANSWERS FOR WEEK 02
by Bob Hagin
Q. About three years ago, at about 90,000 miles, my 1984 BMW developed an intermittent vibration felt in the steering column during hard braking at speeds in excess of 50 MPH. A technician who road-tested it back then said it was caused by a warped brake rotor which could be "machined" if it got worse, but he did not feel it was necessary at that time. It has not gotten worse since then and I have learned to anticipate it when braking from high speeds. The car is due for a periodic inspection soon and I am wondering whether to have the job done now. Does it sound like a warped rotor? What are the risks of "living with it" and why is it intermittent versus constant? The car now has almost 122,000 miles on it.
A. Usually a warped brake rotor produces a pulsating feel in the brake pedal rather than a vibration that comes and goes. A warped rotor is kind of like a bent wheel on a bicycle. It can be resurfaced to be "true" unless a resizing would reduce the thickness of the rotor to less than the legal limit. That limit is a number that is cast into the rotor itself somewhere. The job requires resurfacing of both left and right rotors so the coefficient of drag (smoothness) would be the same from side to side. If not, the brakes could "pull" when applied. It's easy enough for a technician to check for warped rotors using a dial indicator. The maximum run-out allowed is usually around .005 inches. Since the problem with your BMW is intermittent, I'd be more inclined to suspect a fault in its steering system. I suggest that you have the entire front end (including the steering system) inspected closely rather than assume that a rotor is warped.
Q. My 1993 Nissan Pathfinder V6 has a water leak somewhere and a mechanic told me that it was coming from a leaking head gasket. I was quoted a very high price for replacing the gaskets on both sides and resurfacing the heads. The car doesn't run bad and I'm wondering why it would do so if the head gaskets were leaking. I had another car (a Cadillac) that had a leaking head gasket and it ran so badly that I couldn't drive it. Is there some other place the water could be coming from besides a head gasket? It has a little over 90,000 miles.
A. It's possible that the coolant leak in your Nissan is coming from a loose coolant jacket plug that's located behind the camshaft drive system. It's a real hassle to even inspect for traces of leakage because it's underneath the camshaft drive sprockets and the head-high parts of that drive paraphernalia have to be pulled to get at it. The repair is to pull the plug, clean up the threads, apply thread sealer and replace all the parts that have been taken off. It's a couple of hours worth of work to give access to a ten-minute job.
Q. I was recently given a pair of 1960 British Sunbeam Alpine sports cars that sat in a barn for perhaps 20 years. One is in terrible shape but the other is all in one piece. I had a couple of British sports cars in the late '50s and early '60s and would like to try making one good one out of the two. Are the any places left that can supply me with any new parts that I might need? I don't want to make it perfect but I'd like to drive a fairly good one around on weekends. The Tiger version of the same car had a V8 in it. Can I put a V8 one in one of these cars.
A. The Tiger version was based on a later model and to install a V8 in an Alpine takes lots of work and the result is usually a mess. The recent issue of Hemmings Motor News lists a couple of shops that supply Rootes (Sunbeam) parts. You can buy a copy at the magazine sections of most large book stores. But try to not get carried away. It's easy to go overboard and put a lot more money into a project car than it's worth.
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