ML 270 cdi cold start problem

[noddles64]

Hi all,
I know this is not a new problem, but maybe one of you can help me.
I have an ML 270 cdi 12 years old 90,000 on the clock, bought Oct last year,
It has a starting issue, when left for a few days its a pig to start, Its had a full service by my local garage (who owns an ML) New battery as the one on it wasn't really up to the job, one of the injectors has been replaced as it was faulty all the others are ok.
Once I get it started it runs fine and starts again with no problems, its just frustrating that when left for three or four days its really difficult to start, there is a trace of a diesel leak, very small, garage that serviced it says that the fuel pump has a misty trace of a leak.

Any thoughts?

 

[joesoap]

replace the fuel lines going into the pump or at least the O rings in the ends first. Its a well known issue and easy to do.
It could be leaking at those or at minimum letting air in to the lines.
The ML has only one pump none in tank, so air getting in lets it run back to filter and tank.

 

[noddles64]

Thanks joesoap,
I've seen that on this forum before is it easy to do (any pics) can I get o rings on line?

 

[MOZ]

Hi, the O rings and the white seals (I recommend you get these too) are pence from the main dealer. You can probably get them cheaper online, but for the sake of a couple of quid for half a dozen of each, i would go to MB dealer.

It is a straight forward job but fiddly. The access to the 2 hoses on the left of the High pressure pump is limited, you will need a small ratchet (with a 3 or 4 inch extender bar to access the bolt holding the clamp plate that holds the 2 hoses in place.

These hoses and the plastic connections become brittle over time, so there is a risk of cracking them (they aren't the easiest things to pop out, and are likely to break if you try to prize them out with a screw driver.

As long as you are careful, don't rush and don't try to bend the pipe too much after removal (you will need to twist and move them a little to get access to remove the old o ring and seal and fit the new ones.

making sure the connections line up and push back into the HP pump straight it is worth taking time over, if they are inserted at an angle, you may have problems with them sealing properly and leak or break.

Take care refitting the clamping plate and its screw making sure you don't cross thread the screw.

Access for all of this work is tight especially if you have big hands, and its fiddly but perfectly do able.

All the other hose ends are easy after these 2 as they are more accessible and have quick release plugs on them (just make sure you understand which way the tab opening clips work (will be yellow or white) some push down some pull up to release the retaining tabs (which again may break if your not careful. Also they will be stuck in, and may take some force to pop off (careful of breaking them if you are tempted to prize them off with a screwdriver blade - avoid that if possible)

as I say be careful of both the tube and any black plastic connections as they do get brittle with age.

Once it is all done , you will need to crank the engine a good few times (maybe 30 secs to a minute) before it will fire up.

in a nutshell, straight forward, but a bit fiddly - poor access and be careful not to break the fuel lines.- if you do break them - they are available from Mercedes for about £35 for a fully molded replacement part (one of the lines only!), so not a complete financial disaster if you break them.

This tread on another forum may help you visualise things (although it doesn't show the tricky stuff I mention above.
http://mbworld.org/forums/m-class-w163/565417-ml270-diesel-unidentified-t-bleed-contraption.html

Good luck and hope this helps.

 

[joesoap]

As Moz says just be careful getting the old ones off they need a good pull to get them out not a job you want to do on a cold day as they get brittle from age and cold dont help.
Do it on a day dealers will be open in case you need to replace pipes.

 

[BlackC55]

Replace the pipes. They get brittle. Inexpensive to buy too.