Webasto Thermo 90, Workshop Manual

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5 Troubleshooting Thermo 90
504
5.4.2 Rear Wall with Metal Evaporator
• The pilot flame exit bore (Fig. 504) must not be
clogged, otherwise there will be no start.
Remedy
Replace burner
• Cracks, delaminations, as well as black or other
discolorations of the evaporator do not cause a burner
failure and are meaningless.
• Coke deposits on the evaporator surface (except
for the pilot flame exit bore) are usual and must not be
removed. When the load changes from full load
to part load and vice versa the burner normally is
self-cleaning.
Fig. 504 Visual Inspection, Pilot Flame Exit Bore
5.4.3 Combustion Chamber
• The combustion chamber (Fig. 505) should not be
damaged (e.g. dented).
A combustion chamber with dents may cause
insufficient combustion or coking of the heater.
Remedy
Replace burner
• The air bores (Fig. 505) in the combustion chamber
must not be coked. Coked air bores may cause a
no-start or insufficient combustion.
Remedy
Removal of coke deposits by careful scraping.
5.4.4 Burner Assembly
• The cables of glow plug and flame sensor must be
routed as shown in Fig. 503.
• The screwed connection of the housing and
combustion chamber must be secure (Fig. 505).
• Housing and combustion chamber (Fig. 505) must be
connected securely without any play (check by slight
movement of fuel pipe).
• The O-ring must have a tight fit around the fuel
chamber upper edge (Fig. 503) and must seal
completely.
• The gap between housing edge and combustion
chamber upper edge (Fig. 505) must not be equal
around the entire circumference.
• The insulation (Fig. 503) must be present.
Fig. 505 Visual Inspection, Burner Assembly
Pilot Flame Exit Bore
Metal Evaporator, Fuel
Pilot Flame Exit Bore
Metal Evaporator, Diesel
Combustion
Swirl Ring
Air Bores
Gap between Housing and
Combustion Chamber
Chamber