Mercedes-Benz W126 petrol smell and fuel leak
W126 smells of petrol, where does the smell come from?
The cause can be a cracked EHA (electro-hydraulic actuator), in which case the area around it is damp, or a rotted fuel vapour filter inside the left fender. Also check the fuel hoses, injectors, filter connections, fuel filler cap and the vent system.
What should be noted about replacing the fuel filter and a leaking banjo fitting on the W126?
The filter's mounting clamp can corrode the filter, so the spot can be protected with tape. The plastic clamp of the new filter is not left out. The copper or aluminium washers of a leaking banjo fitting can be made softer by carefully annealing them and cleaning the surface.
Is it normal for the W126 fuel filler cap to hiss when opened?
Yes. The hiss is caused by vacuum in the tank, and it is stronger the emptier the tank is. If fuel overflows from the cap in hot weather, the petrol has expanded or the vent system is blocked. In summer the tank should not be filled completely full.