Steering Wheel Vibrates

When my 1984 Proton Saga is idling, the steering wheel vibrates. When I step lightly on the accelerator, the vibrations case then return when I lift my foot off the pedal.
A mechanic fiddled with the carburettor and the vibrations went away, all this when the engine had been running for a few hours. when I started the car next morning, the vibrations returned.
What happened to those electronic tuning machines? I don't see them anymore. Most mechanics tune by ears now.

Reply:
All four-cylinder engines have vibrations at low speeds, especially at idling. When the car is new and all the engine mountings are relatively soft, one does not feel the vibrations as they are absorbed by the mountings. As the mountings get older, they tend to get harder and the vibrations are easily felt. Also, the load of the air conditioning compressor tends to make engine vibrate more at idling and if the idle speed is increased slightly, the vibrations will go away. If the idling speed is not excessive like 1000 rpm, a slight increase of idle speed can eliminate the vibrations.
Otherwise, you may need a tune-up including valve tappet adjusment to get the engine to run more smoothly.