The Mercedes-Ben 560 SEL is a 1989 YEAR whight smoke when runing

White Smoke from the exhaust, is a good sign of blown head gaskets. Check the oil dipstick for signs of water in the crankcase ( milky white oil ) and smell of antifreeze in the exhaust, oil in radiator. Any of these are further indicators of head gaskets. You need to do a compression , combustion, or leak down test to verify.