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Back and Forth About Car Rocker Arm

November 06, 1986|RALPH VARTABEDIAN | Times Staff Writer

Question: I start with the dealer. He says he never heard of any rocker-arm noise complaints in the 1974 Mustang II 2800 cc. I wrote no less than four times to Ford, made one phone call to Detroit. I never experienced, except from civil authority, such ignorance, such sidestepping, such glittering, inane communication. The final letter from Ford said: "Please contact a dealer in your vicinity." What now?--L.C.S.

Answer: You're right that dealing with the bureaucracy of Detroit can be second only to our own federal government, but you should have been able to get your problem resolved without as much grief as you have experienced.

In fact, the 1974 Mustang II with the 2800 cc engine has above-normal rocker arm noise, because it uses something called a solid lifter.

The valves inside your engine and in many other American cars operate with push rods that take power from a rotating shaft in the engine and convert it to the up-and-down motion that opens and closes valves.

In some cars, push rods do not rest directly on the shaft that powers them. Rather, there is something called a hydraulic lifter in between. A hydraulic lifter is filled with fluid and keeps zero tolerance between the two metal parts. With that cushion, the engine stays quiet.

By comparison, a solid lifter maintains a very small amount of free play between the metal parts, on the order of several thousandths of an inch. When the metal parts come together, they make noise.

The Ford solid lifters are known to be noisy. But possibly, your lifters are noisier than usual because they need to be adjusted. A hydraulic lifter never needs adjustment, because the fluid device always maintains zero play.

A solid lifter needs to be adjusted periodically, because normal engine wear throws them out of adjustment. Typically, Ford advises the valves be adjusted at 7,500 miles, 15,000 miles and every 30,000 miles thereafter.

Q: I have a 1979 Pontiac 301 V-8 engine. My problem is that oil discharges into the air filter and stalls the engine. I have tried everything. I would appreciate it if you could advise me on what to do.--H.K.

A: Your engine is designed with a crankcase ventilation system that is designed to purge contaminated and corrosive fumes from the lower area of your engine. But the ventilation system is obviously sending oil vapor or droplets, instead of just fumes.

The first, and easiest, thing to check is the positive crankcase ventilation valve or PCV valve. It's located on the valve cover and has a hose attached to it that goes to the air cleaner. Pull the valve out and make sure it rattles when you shake it.

If that's OK, then make sure your mechanic has not overfilled the engine with oil. Sometimes, dipsticks are incorrectly marked. You can check it by draining the old oil and refilling the engine with the correct amount of new oil. The dipstick should be right on the full mark.

If all that checks, you might also check that your crankcase breather cap, if your engine has one, is not plugged. If it is, soak it in kerosene overnight.

Q: I was told my shock absorbers need replacement. Is that a job that I can do myself?--D.D.

A: Even for a skilled home mechanic, it's generally not worth the headache. Shock absorbers usually rust onto a car's frame and can take hours for a backyard mechanic to free. You also have to crawl under the rear of the car, which is an unpleasant way to spend a Saturday.

Many discount auto-service operations sell shocks on sale and do the installation for a small price. Go that route and spend your Saturday at the ballgame.

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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