Additional heater installation details (models 463.250/323, code H12)
1 - Cooling tract outlet hose; 2 - Cooling tract inlet hose; 3 - Fuel line; 4, 5 - Couplings; 6 - Bandages; 7 - Exhaust pipe; 8 - Mounting bolts; A6 - Additional heater unit (STH)
1. Jack up the car and place it on supports.
2. Remove the crankcase guard.
3. Drain the cooling system (see Chapter Routine care and maintenance).
4. Disconnect the inlet (2) and outlet (1) coolant hoses from the STH heater and water pump assemblies.
5. Disconnect the fuel line (3) from the STH heater assembly (A6) - prepare to collect any spilled fuel.
6. After releasing the bandages (6), disconnect the couplings (4 and 5) of the electrical wiring - the bandage tapes must be replaced without fail.
7. Disconnect the outlet pipe (7) from the STH heater (A6).
8. Unscrew the mounting bolts (8) and remove the STH auxiliary heater assembly (A6).
9. Remove the circulation pump (see Section Removal and installation the circulation pump of the additional heater STH (with appropriate equipment)).
10. Installation is carried out in reverse order.
11. Finally, bleed the cooling system and check the relevant components for signs of developing leaks.
12. Start the additional heater and make sure it is functioning properly, - if the heater switches off automatically before the coolant temperature reaches the normal operating value and cannot be restarted, therefore a false blocking is triggered in the system, - take the car to a Mercedes-Benz service station for detailed diagnostics using the STAR DIAGNOSIS reader (6511 1801 00).