1989 Mercedes Benz 560sel smoking upon accelaration

Smoking under acceleration may be an indication of more serious problems. If the smoke is black you are burning oil. If it is white you are burning coolant. I would recommend checking the oil for contamination. Pull the dipstick and check the color of the oil. If it is milky in color you have a blown headgasket. Also check the coolant for any presence of oil. Again, an indication of a blown headgasket. Other possibilities would be leaking oil rings which can result in smoke from the exhaust.