I have recently bought a 1990 model 230E which has already clocked 250,000 kms. The engine seems to be smooth and quite powerful. I noticed that when i spped up to 140 KMPH spped the exhaust emits black smoke. I also noticed stains of oil on the rear end of the car. Otherwise the car performs well at speeds below 120 KMPH. Is this normal or does this call for engine repair. Please help me out on this.
Also i live in a hot country where the temperature is 45 degrees plus. The Engine temperature gauge in the car usaually reads 80 degrees and above. Is it OK if i remove the thermostat from the coolant line to keep the engine temp on the lower side.
Please pass your suggestion to me at firstname.lastname@example.org