mercedes c250d 1993 drawing air?

[rustybucket]

hi,i have had diesel trouble with a L reg 250d and have replaced all the plastic pipes and filter housing.it starts and runs but it is still pushing air up from the lift pump to the filter and back down to the black plastic piece at the side of the pump.can anyone tell me what the black plastic piece is and are there any o rings or seals etc for it.
please advise if you have any ideas.
tanks

 

[tjo]

i think the C250td has a small filter inside the filter housing if it has its the
10mm bolt next to the 19mm one that screws into the main filter, if you take it out clean it and replace the O ring, we find this causes a lot of air drawing problems, cant think what the black plastic thing is

 

[Dunx]

Might be the shut-off valve? Does it have three fuel connections and one electrical connection? If it is, there is an o-ring where it connects to the suction gallery of the injection pump. Just had to replace it on my E300TD as it was leaking fuel and drawing air. The o-ring was totally flat.

 

[rustybucket]

Might be the shut-off valve? Does it have three fuel connections and one electrical connection? If it is, there is an o-ring where it connects to the suction gallery of the injection pump. Just had to replace it on my E300TD as it was leaking fuel and drawing air. The o-ring was totally flat.

hi,thanks for the response,i hope you have solved my problems,it does have three fuel lines and 1 electrical connection,i have replaced every other o ring,bolt and line on the car so i am nearing my witts end.i will source the part and mail you back with my result.
thanks

 

[rustybucket]

i think the C250td has a small filter inside the filter housing if it has its the
10mm bolt next to the 19mm one that screws into the main filter, if you take it out clean it and replace the O ring, we find this causes a lot of air drawing problems, cant think what the black plastic thing is

hi,thanks for the responce,i have already repaced the filter bolt and o rings.i have recieved another reply relating to an o ring inside the fuel shut off valve,i will try this and see.
thanks again

 

[racall]

hi,thanks for the responce,i have already repaced the filter bolt and o rings.i have recieved another reply relating to an o ring inside the fuel shut off valve,i will try this and see.
thanks again

I replaced That seal as i had the same problems as you.The hardest part was finding the screws that hold the shut off valve onto the pump,One is easy to see one is hidden.

 

[Dunx]

Originally posted by racall
The hardest part was finding the screws that hold the shut off valve onto the pump,One is easy to see one is hidden

One screw is in a recess above the electrical connection, the other is on a flange at the back of the valve, which is difficult to see. On mine they were Torx screws; T25 I think.

 

[Dunx]

T25 I think

I lied! They were T30.
Sorry!

 

[pcman_jh]

Re C250 drawing air

My 1994 C250D needed its fuel bleed pipes replaced - the ones that run between injectors. Although they looked OK visually, two of them crumbled in my fingers when I went to replace them. I too had changed every O ring there was, so this was the last resort and it didn't give me any other bother for the year until I sold it (and running with up to 50% veg oil, but that's for another thread...)

 

[BIGSTEVE]

C Class Diesels Hard To Start From Cold

Hi Guys, I Have Had Sveral Hard To Start C Class Diesels In My Workshop, There Is An Electronic Fuel Shut Off Valve Which The Main Dealers Sell To Stop The Fuel Runing Back To The Tank, This Has Been Helpful On Many C Class Diesel Faults More So When Very Cold And When The Vehicle Has Been Left Overnight, Regards Steve.