C250TD air in fuel system

[oggy]

Recently had to call out RAC to start my 1998 C250TD. It took nearly an hour to get air out of the pipes between the fuel filter, lift pump and injector. Bloke said it sometimes happens and can be difficult to find the source. Has been alright for over a week now but I have noticed a small air bubble in one of the clear pipes.
I thought this was a self priming system and didn't need bleeding.
Anyone with any clues?

 

[gregit]

Air

HI,
the clue might be filters,or tank breather,if the system is unable to pull fuel through it will pull air from joints in pipes etc,anywhere it can basically :roll: So if no obvious pipe splits etc.also include fuel pick up filter in tank if an older system

 

[Bolide]

On the late W124 diesels this effect can usually be cured by replacing the O-rings on all the fuel pipes under the bonnet

Assuming the C250TD gas a similar setup you'll find that the O-rings flatten out over time and tend to leak when disturbed. There are two sizes of O-ring so pop down to the main dealer and get 6 or 8 of each. Then carefully disconnect all the pipes to and from the injection pump, fuel filter & etc and replace all the O-rings

Before you buy the O-rings just check with the service department to see if the C250TD is the same as a W124...


Nick Froome
http://www.w124.co.uk