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Worn Valve Housings Are Poor Guides

December 31, 1987|RALPH VARTABEDIAN | Times Staff Writer

Question: I have a problem with my 1982 Oldsmobile Cutlass Supreme Brougham, which has six cylinders. I recently purchased the car used when it had 42,000 miles on it. I then discovered it was using about a quart of oil every 500 miles. I also get a lot of pinging, even though I use premium gasoline.

I took the car to an Olds dealership, which changed the exhaust gas recirculation valve and the positive crankcase ventilation valves, but the problem continues. What do you recommend?--F.B.

Answer: The symptoms you describe are very likely caused by worn engine valve guides, a diagnosis that can be confirmed by your mechanic if he checks the condition of your spark plugs.

Valve guides are the tubular metal housings in which your engine valves move as they open and close to allow fuel into the cylinder and exhaust out of the cylinder. The tolerance between the valve stem and the guide is very close, and when the guide wears down, it permits oil to be sucked into the cylinder.

The oil that leaks into the cylinder then causes the spark plugs to become fouled, which in turn can result in the ping that you describe. The oil is eventually burned up and passed out the exhaust. In older cars, burned oil causes a blue exhaust smoke, but the higher combustion temperatures of newer cars burn the oil more completely, so you cannot depend on blue smoke to reveal oil burning inside the engine.

In your Oldsmobile engine, the right bank of cylinders usually runs hotter, and the cylinders on that side of the engine are likely to contain the worn valve guides. When your mechanic checks the spark plugs for oil fouling, he is likely to find the problem there.

Q: I am desperate for advice on my 1974 Audi. It runs well, but it has a bizarre problem that no one--including several Audi specialists and the dealer--can diagnose, much less cure.

Whenever the steering wheel is turned left past a certain point, the engine dies. The point is far enough to the left that it is only a problem during U-turns or while turning into parking spaces. The problem does not occur when the wheel is turned right. Sometimes the car will not start if the wheel is turned to the left. This developed only several months ago. The car does not have power steering and the air conditioning has been removed. Any ideas?--V.E.

A: I had hoped the solution to your problem might be well known among Audi specialists but I've found your case may be highly unusual. In cars with power steering, such stalling problems can often be traced to the power steering pump and the loads that it can place on the engine. But with manual steering that's not possible.

The most likely general cause of the problem is some sort of electrical short or open circuit that occurs only when the steering wheel is in a certain position. Unfortunately, that leaves open a lot of territory.

Your mechanic should start looking into such potential causes as a loose starter motor, a loose connection between the engine and the transmission housing, a loose grounding strap on the transmission and a hairline crack in the starter housing motor.

The other area for investigation would be in the steering column. Although the steering shaft is isolated from the electrical wiring in the steering column, there may be something going on that is causing a short. When it comes to electrical problems, it is almost impossible to predict what will cause a short or open circuit.

Ralph Vartabedian cannot answer mail personally but will respond in this column to automotive questions of general interest. Do not telephone. Write to Your Wheels, You section, The Times, Times Mirror Square, Los Angeles 90053.

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