STILL air in my fuel!

[turbopete]

yes! im back with this old chestnut again! never sorted it but i must have narrowed it down! replaced fuel tank strainer at the weekend. (i may do a write up and some pics as its a 210 and from what ive heard its a little bit different to the 124.) on initial start up, ticking over, (injector?) rattle was reduced, until revved up then it returned fully. having now done about 100 miles it rattles as much as ever. the starting situation is also still poor. if i look under the bonnet at the clear plastic fuel lines, air is present at the 1st point fuel is visible, so ive come to the conclusion that its either the metal pipes which appear to be in good condition for a 10 year old car, the fuel heater or the rubber fuel hoses in the engine bay and anything else the fuel passes through between the metal pipes and the fuel heater. anyone any ideas? short of just replacing whatevers left that i havent already replaced?

 

[roofless]

any diesel sweating from the system even a very small damp patch

 

[turbopete]

not that i found when i was underneath the car. admittedly i was doing the tank strainer on a trolley jack and axle stands! and ive not seen anything where the rubber hoses join the metal pipes at the top of the bulkhead in the engine bay. never looked at the heater yet. im guessig it will be expensive so hoping its not that! i must check it next time im under the bonnet though. in fact i will go and look now!

 

[turbopete]

the area on the fuel heater that i can see appears to be bone dry. i will have to get a mirror to inspect the side nearer the glow plugs and the side nearest the rear of the car though

 

[roofless]

the fact air can get in is not to say diesel will get out but it's worth a look

 

[turbopete]

true. im getting towards the point where, short of replacing the entire feed side of the fuel system that hasnt already been replaced, im stuck for both cash AND ideas!!!

 

[roofless]

have a look at this diy section it might spark a idea or two http://www.peachparts.com/Wikka/DoItYourSelf

 

[turbopete]

not much else left to change!

 

[Parrot of Doom]

The metal pipes won't have anything to do with the air in the lines, they're high pressure pipes from the pump, if they were leaking you'd see damp patches.

Its the pipes that deliver fuel to the pump you need to concern yourself with, the seals around the filters, and the o-ring on the shutoff valve. On that side of the pump the fuel is 'sucked' up, which is why you see air in the lines, and not diesel spitting out.

 

[turbopete]

the metal pipes i was referring to are the ones that go from the rubber hoses at the tank, along the underfloor of the car ande up the bulkhead where they join up with rubber hoses again. sorry if i was unclear about that. as for the o rings and eals etc around the filter and pump area, every single one as been replaced. i can see the bubbles travelling along the clear plastic pipe between the fuel heater and the fuel pre filter next to the main fuel filter, so i know it must be between the tank and that clear pipe. im just not sure what other than the fuel heater itself could be the cause!

 

[turbopete]

incidentally, i tried parking it facing slightly downhill since my last post, after running for approx 1 minute. left for about 2 mins and car was reluctant to start again. dont know if that helps anyone with any ideas?

 

[Parrot of Doom]

You could try a simple bypass system - that might isolate the leak:

http://www.peachparts.com/shopforum/showthread.php?t=113596

 

[turbopete]

i had thought about that. i'll have to see if ive got any of my oul plastic pipes to cut up. dont want to cut up my new ones if i can avoid it!

 

[Hertfordshire Merx]

Have you checked all the injectors for spill leaks, this is a common failure on Mercedes and causes this problem.

Basically you disconnect the spill pipes and pinch up the pipe after the last injector, and use a measuring kit attached to the spill pipe connector at the top of the injectors to check how much fuel is being 'rejected' from them. If any are out of the ordinary (excessive) the injector will need replacing.

 

[turbopete]

i havent tried that yet, no. that would possibly cure the poor starting/rattling but im not sure how that would prevent the air running in the fuel lines problem! however, im quite sure that you will be considerably more knowledgeable than me about the subject and all input is much appreciated!

 

[turbopete]

havent found any old pipes yet, but is that clear fuel hose you can buy suitable for diesel? where does the feed hose go to that comes from the tank to the fuel heater? whats at the tank end of it?