Section 8 - Cooling System - Group 08 Heater Housing, Thermostat Support and Water Header Cover (8-09) M11 Page 8-41 Use a wire brush to remove the rust and corrosion from the engine heater housing surface (1). Use a wire brush to remove the rust and corrosion from the thermostat support surface (2). Use a wire brush to remove the rust and corrosion from the water header cover surfaces (3 and 4). Warning: When using a steam cleaner, wear protective clothing and safety glasses or a face shield. Hot steam will cause serious personal injury. Use steam to clean the parts. Dry with compressed air.