OM642 in ML280 Ed-s Air getting into fuel rail?

[rossy]

OK pretty sure air is getting into the fuel system but no leak as the longer I leave it....harder to start....but...if I leave ignition on.....say after a few days I can hear the "gurgling" of the fuel pump getting rid of air. Also starts much better if I wait too.....so think defo pressure loss/air ingress.....
Oh and its got 6 new Bosch Duratek glowplugs, brand new latest GP Module and for peace of mind extra earth strap from the one that feeds module on top of engine to chassis!!

So for those that don't know....it has just had all 6 injectors but this issue was there before....so will still check and replace leak off o-rings to illiminate that some maybe damaged (came all new with injectors)

I did notice a very small leak on a very short fuel pipe ages ago....3" max in centre of engine which had the wrong fuel line clamps on...julilee which I nipped up....so this will be my 1st point to check.
I've bought new screw hose clamps that do not PINCH like Julilees do, they tighten more uniform...

My question is, are there any other know places for fuel lines to go...were air gets in but diesel does not get out???

Cheers

 

[mersum1es]

OM642 has primer pump in the tank, so low pressure lines should point the leak as a fuel out.

If fuel filter lines mid of the engine are no tight, thats a one point to check for sure.

Are injector new or refurbished? Did you code them to ecu?

 

[Doug1234]

Don’t change the leak off o rings unless you can see fuel leaking from them , because if you break a clip its a full leak off hose setup as you cannot buy single clips .
My take would be fuel filter needing changed or weak in tank lift pump.

I have Jeep with same engine and I hear pump running in mornings before start, but only time I hear air gurgle through lines is after filter change as it all primes.

Is there a one way valve inside tank ? , maybe fuel runs back to tank so pump has to prime line to high pressure pump before it can start ?. This may explain no leaks

 

[rossy]

"Is there a one way valve inside tank ? , maybe fuel runs back to tank so pump has to prime line to high pressure pump before it can start ?. This may explain no leaks"

This to me seems to be whats happening....can't see there being a valve as most know the high pressure is gone when ignition off.....with valve the high pressure would stay....or thats my thoughts on it anyway.

Going to check the fuel line once the weather inproves as sick of swpping all the cars around to put the ML in the garage!

Also waiting for new clips to arrive.....so lines can be removed....fully inspected and put back if I think they are ok....I still suspect the once that leaked and I nipped up months ago......also being streight pipe I can easily replace to rule out...

 

[Doug1234]

It doesn't have a saddle type fuel tank does it ?.
If it does it could be doing the classic C class effect where under half to a third tank the engine runs out of fuel as it cannot get it over to the other side of tank to be picked up.

 

[mersum1es]

There is no check valve in MB system, solid system does not need it. Some put it in there but if system is ok, it just cause extra flow resistance (and is source of pressure virbations in dynamic changes). Repair you filter line and try again.

 

[Uncle Benz]

They do get harder to start from cold with old age. My own ML will struggle to start from cold if you crank it the moment the glow light goes out. If I count to five after it extinguishes it will start instantly. I actually resolved the same issue on a customer car the other day. All the glowplugs had been replaced with Bosch items, but it would crank for ages from cold. I tested the glowplugs, but they were all working. On a hunch I bit the bullet and bought six new ones from Mercedes. Now it starts perfectly every time as soon as the glow light goes out. I’m going to put a set of genuine glowplugs in mine asap to see if it fixes that one too

 

[Uncle Benz]

Oh, and an egr valve that is seating poorly can lead to a long crank too. Sorry to give you more things to check

 

[rossy]

New glowplugs were Bosch Duraterm changed all 6 and new GP Module too......and its exactly the same as it was before....once running it starts better......left overnight have to leave ignition on and wait for the gurgling sounds to stop....then starts much better. I 99% sure its air getting in.......just need to find were......I'm going to put it back in the garage this week while I investigate. Just dont like leaving the AMG on the drive.....tho I love both my Mercs Obviously

 

[rossy]

They do get harder to start from cold with old age. My own ML will struggle to start from cold if you crank it the moment the glow light goes out. If I count to five after it extinguishes it will start instantly. I actually resolved the same issue on a customer car the other day. All the glowplugs had been replaced with Bosch items, but it would crank for ages from cold. I tested the glowplugs, but they were all working. On a hunch I bit the bullet and bought six new ones from Mercedes. Now it starts perfectly every time as soon as the glow light goes out. I’m going to put a set of genuine glowplugs in mine asap to see if it fixes that one too

What are GENUINE ONES?

 

[Uncle Benz]

Mercedes ones are Beru if memory serves

 

[rossy]

Mercedes ones are Beru if memory serves

Ones I took out are Beru....says 4.4v on side as kept the old ones ( bit of a garage hoarder ) so had a little pannick....but the Bosch ones are listed as 4.4v-5v so guess right....not like I put cheap ones in....

 

[Uncle Benz]

I don't think Bosch stuff is as good as it used to be...

 

[M80]

I seem to remember that glow plugs can be different voltage ratings, and need to match the controller??

Are the controllers of different ratings too. As recently I remember reading that they put out a higher voltage to enable starting and then drop the voltage back some, with a signal from the CPS I suppose?

My earlier C320CDI was a slow starter but back then I thought glow plugs were just 12 volts.

 

[rossy]

I don't think Bosch stuff is as good as it used to be...

Poop...heres me thinking I at least put summat decent in....still think its air getting in and fuel returning to tank........

 

[rossy]

Frightened to say....but it seems like its fixed.....it would always GURGLE if the ingnition was off for even for a short time and start lumpy now it does not, but will only know for sure in the morning!!
Please please everyone cross your fingers for me as I've been stressing over it and just want it right!!

Will let you know what happens in the morning and details of what I did exactly if it fixed......

 

[rossy]

OK meeting myself comming back.....left overnight and no gurggling noise when ignition put on so seems all air leaks into the system are sorted....started better...but not great and quite a bit of white smoke. So assuming the air leak was prior to me changing the glowplugs (and the reason as thought thats what was wrong) and glowplug module I've taken the "brand new" Bosche Duraterm ones out and put back the Deru ones (Lucky I have HUGE amounts of Ceramic Paste). Issue now though is although engine not hot its been run....but it does in my opinion start much better with the originals back in. Obviously left the new Module in....
So will have to wait until its cooled again.
when I got it tho it was from cold on the button....i.e. from cold....soon as light out it would fire right up.....
Fingers X'd yet again.....happy to write off the £42.48 for all 6 bosche ones if its just right!!!!!

Love the car....but this has broken all records for cars I've owned (and thats a lot LOL) for issue after issue......

 

[rossy]

Just tried it again...starts but not on the button....then bit white smoke.....then settles....
Maybe now I just have to let the ECU learn the Injectors.....

 

[Uncle Benz]

If it persists buy some new Beru glow plugs. My thoughts anyway

 

[rossy]

Uncle Benz how would you set an injector relearn proccess?
Would putting in the same codes or maybe changing one charector...saving...then putting it back do it on my IcarSoft MBII??

Just wandering if it would help things along.....