Water pump, thermostat, radiator, expansion tank, and coolant hoses.
The complete list of jobs to do on a high-mileage E46 M3. This is the checklist every owner approaching 100k miles should work through — sorted by urgency and cost.
Essential maintenance and repair guides for new E46 M3 owners. Start here — covers regular maintenance plus the critical preventive jobs unique to the S54 engine.