The E36 M3 cooling system is a universally acknowledged weak point requiring proactive replacement every 60-80k miles or 5 years, with plastic water pump impellers, plastic thermostat housing, radiator end tanks, and expansion tanks all known to fail catastrophically; neglect can crack the head from overheat.
Cooling system fragility and refresh requirements
BMW E36 M3 (US-market, 1995-1999) · mechanical