7 Servicing
Thermo Pro 90
702
7.5
Removing and installing heater
CAUTION
Hot coolant leaking out can cause burn injuries.
7.5.1 Removal
1. Disconnect vehicle battery.
2. Remove heater fuses.
3. It is not necessary to release the control unit cover to
remove the vehicle-specific wiring harness.
4. Unplug the wiring harness connector at the heater (do
not pull the cables).
5. Depressurise coolant system.
NOTE
Protect all open plugs and connectors from moisture and dirt.
6. Release hose clips and detach the coolant hoses from the
water connection pieces on the heater. Prevent coolant
from dripping out of the coolant hoses.
7. Release and detach combustion air line and exhaust pipe
at heater.
8. Release hose clips, detach fuel line. Close off fuel connec-
tion socket at heater and fuel line with suitable plugs or
similar.
9. Remove the three screws and washers from the heater
mounting bracket.
10. Remove the heater.
7.5.2 Installation
1. Place heater in installation position and secure with the 3
screws and washers.
2. Connect fuel line and secure with hose clip.
3. Connect coolant hoses and tighten hose clips to 8 Nm.
4. Reestablish all electrical connections.
The 12-pin vehicle-specific wiring harness connector and
the 2-pin fuel pump connector must audibly snap in.
5. Connect combustion air line and exhaust pipe.
6. Connect vehicle battery.
7. Bleed coolant circuit.
8. Bleed the vehicle fuel system if necessary.
ATTENTION
Reversing the polarity of the power supply can damage the
control unit. Ensure correct polarity of the connection cables.
Direct connection to the power supply without an intermedi-
ate fuse is not permitted.
7.6
Visual inspection to assess the burner
unit
Pay attention to the specific features of the burner unit when
it needs to be replaced or is faulty.
The criteria for a thorough check are listed in the following.
To remove and install the burner unit: See “Burner unit and
glow plug” on Page 805.
First check that the burner unit is complete and not damaged.
7.6.1 Metal fiber evaporator
•
Cracks, flaking as well as black or other discoloration of
the metal fiber evaporator (3, Fig. 701) will not cause the
burner to fail and do not impair operation.
•
Carbon deposits on the evaporator surface are normal;
the burner unit normally cleans itself when changing
from full load/partial load and partial load/full load.
•
The burner unit must be replaced when the metal fiber
evaporator is partially burnt through.
•
The burner unit must be replaced when the retaining ring
is deformed such that the metal fiber evaporator is not
pressed down correctly.
Fig. 701 Visual check, burner back plate
1
Retainer (3x)
2
Glow plug
3
Metal fiber evaporator
4
Combustion chamber
5
Fuel pipe with back plate
1
5
1
2 3
4
1
