ML270 fails to start ad-hoc?!

[carld2606]

Hi all!

Any help would be much appreciated here to try and work out why my '55 diesel ML270 with 97k miles decides not to start at intermittent times. I've replaced the crankshaft sensor but still the same issue.

On varying occasions, the engine starts but doesnt fire up and then I leave it for 3mins and then it starts again but I really have to pump the gas pedal to get it started. Wife and baby were just stranded this morning for 10mins when it failed to start for her..

Mercedes Garage at a loss as no reports come up on their computer..
Cheers,

 

[panason1c]

More than likely an air leak in the fuel system......check for any leaks on the high pressure pump, especially from a cold start as that is when the leak is more pronouncd (hp is at the very front of the engine) its also probably best to renew the fuel pipes as the seals tend to harden and allow air into the system.

The above fault doesnt throw up any fault codes.

 

[carld2606]

Hi panason1c - thanks for that tip.. Will try that out and see what happens

 

[tony jr]

As Panasonic said it could be an air leak or high pressure pump leak but it could be that one or more of your injectors have a leaking high pressure seal giving an excessive leak off and preventing the rail pressure reaching 200 bar thus preventing your car starting. If this is the case then you will find this is intermittent at the start depending on temperature and viscosity of the diesel gradually it will get worse. You will find the car will start with a spray of easy start but I would suggest that you have a leak off test carried out to see if this is the case. If an injector is leaking off then the high pressure seals can be replaced insitu without having to remove the injector.

 

[carld2606]

Fixed!

Hi guys - thanks for your help. FYI, we replaced the o rings and still no luck. We then checked all the fuel lines from tank to high pressur e pupm and found a v small hole in the fuel filter. Now replaced and 4 days in, it 's still working fine. Fingers crossed this is it!
Cheers