Removal and Replacement
Remove/install heaterMODELS
901.0 /3 /4, 902.0 /3 /4, 903.0 /3 /4, 904.0 /3 /4 with CODE (HDB) Hot water auxiliary heater
1 Coolant hose
2 Coolant hose
3 Bolt
4 Washer
5 Heater unit
6 Hose clamp
7 Fuel pipe
8 Hose clamp
9 Hose clamp
10 Clamp
11 8-pin connector
1 Remove left front headlamp
2.1 Remove headlamp cleaning system
3 Remove front bumper
4 Pinch off coolant hoses (1, 2)
5 Remove circulation pump from heater bracket
Place circulation pump to one side. Do not disconnect the hoses.
6 Detach coolant hoses (1, 2) from heater connecting pipes
Collect escaping coolant in a clean vessel.
7 Remove fuel line (7) from heater unit
Seal fuel line using a suitable plug
8 Release clamp (10) for exhaust-gas line
9 Remove exhaust-gas line from heater
10 Unplug 8-pin connector (11)
11 Undo screws (3) and remove heater unit (5)
12 Install in reverse order
13 Start engine and bleed cooling and heating system.
Allow engine to warm up with alternating speeds for approx. 1 minute. Top up coolant continuously up to top mark in the coolant expansion tank.
14 Switch off engine
15 Check for leaks on coolant hose connections
16 Check auxiliary heater for proper operation
MODELS 901.6, 902.6, 903.6, 904.6 with CODE (HDB) Hot water auxiliary heater
MODEL 901.6, 902.6, 903.6, 904.6 with CODE (HZ9) Heater booster, diesel engine
MODELS 901.6, 902.6, 903.6, 904.6 with CODE (HZ5) Warm air auxiliary heater 10 kW with timer
1 Fuel pipe
2 Supply coolant hose (warm)
3 Return coolant hose (cold)
4 Warm water heater unit
5 Screw for heater unit
6 Heater unit bracket
7 Intake line
8 Exhaust line
X164 Warm water auxiliary heater connector, 2-pin
X165 Warm water auxiliary heater connector, 8-pin
Remove/Install
1 Remove front grille
MODELS 901.6, 902.6, 903.6, 904.6 up to model year 2003
MODEL 901.6, 902.6, 903.6, 904.6 as of model year 2003
2 Remove left headlamp
3.1 Remove heater booster circulation pump from heater bracket for warm water auxiliary heater 10 kW with timer Code HZ5
Place circulation pump to one side. Do not disconnect the hoses.
4 Pinch off coolant hoses (2, 3)
5 Detach coolant hoses (2, 3) from heater unit (4). Collect escaping coolant in a clean vessel.
6 Remove fuel line (1) from heater unit (4)Seal fuel line using suitable plug.
7 Disconnect 2-pin and 8-pin connector (X164, X165)
8 Unclip suction line (7) from both brackets (arrows) on the front-end side panel
9 Undo screw (5) on front end and rear side of heater unit bracket (6)
10 Remove bracket (arrow) of exhaust-gas line (8) from left wheelhouse and remove exhaust-gas line downwards from heater unit
11 Remove heater from heater unit bracket
12 Disconnect exhaust-gas line from heater unit
13 Install in the reverse order
14 Start the engine and allow it to warm to its normal operating temperature. Allow engine to run for approx. 1 min at alternating speeds.
15 Check engine coolant level and top up with coolant if necessary
16 Switch off engine
17 Check coolant hose and fuel line connections on heater unit for signs of any leaks
18 Check auxiliary heater/heater booster for proper operation