I have an '87 300D Euro version with a 4matic drive. At very slow speeds (5 to 10kph), and while making sharp turns, the 4matic system seems to engage. This can be felt because the 4matic pump loads the engine, and the front drive makes clunking sounds. The 4matic and ABS indicator lamps don't go on when this happens. Everything smoothens out once all wheels are again straight positioned. I've checked the wheel speed sensors, and they're all OK.
I'd like to know if this is normal, or if needs correction. I've just bought this car.

Thank you in advance.