W211 E320Cdi starting issues- please help!

[jon_viola]

Hi,

I have a V6 3.0 W211 E320Cdi. Every 2-3 starts it won't start on the button and takes 2-3 complete cycles to get going.

To rectify this so far work has included:

6x glow plugs and relay
6x injectors
MAF's tested on STAR and fine
New Fuel Filter
Fuel pumps pressure tested

Any ideas?!

 

[bob6600]

Wow that's a lot of work. It could be air getting into the system via the fuel lines, faulty O rings or brittle pipes

 

[mersum1es]

Is primer pump pressure tested too? Checked that primer pump 'filter' is free of gunge? Is it all the time, engine cold/hot both? All injectors new or refurbished (leak back test done)?

You have access to star diagnose, check what happens when no start (live data), is it low fuel pressure...

 

[jon_viola]

Hi,

Thanks for your replies. I should have added that it's only happens in the mornings having been left overnight but not with any regularity.

The lifter pump pressure has been tested and is fine.

The new injectors are direct from Bosch.

Where are the pipes and O rings you mention?

Cheers

Jon

 

[mersum1es]

O-rings are not big issue in W211 fuel system... Only pressure regulator o-rings or leaky quantity control valve may be issues. Brittle pipes may still apply.

Sounds like very much inner leak in fuel system, were test done in cold engine then? No point make them in car inside garage, if it's problem only when car has been cold outside overnight...

Might be worn hp-pump too... but like said, star tests at engine cold!

 

[jon_viola]

Hi,

Yep STAR done on cold nothing showing.

Could you tell me where the O rings are at the pressure regulator?

Brittle pipes will be where?

I think belt and braces here and just change the lot....

 

[mersum1es]

I mean also what was real value of high pressure, when no start? Just to pinpoint it is fuel related. IMO It does not give fault code if it low pressure is happening during start, it just not give permission to inject.

Regulator is kind of cartridge valve, it has o-ring on its sleeve body.
http://i.ebayimg.com/00/s/NTE4WDc1OA==/z/nNEAAOxy4fVS-4r5/$_12.JPG (not sure if regulator is precise this kind of in OM642)...

All low pressure lines and connectors may brittle.

Older hp pumps could be DIY tested (if start problems were ALWAYS at cold engine) by heating hp-pump using hot air gun before start. If it started immediately --> worn pump.

 

[jon_viola]

Ok so changed two of the three hoses from pump to fuel filter. The long one from the filter to the pump and the short one from the pump to the steel line.

Still got issues. Will change the O ring on the regulator next....

 

[mersum1es]

read the fuel pressure live data when no start... no point to change more things if pressure is ok.

 

[jon_viola]

Sadly I've moved so don't have free access to STAR any more....

 

[colinp]

i just had very similar problems with my ML270CDI i had changed all fuel pipes and filter in the summer and had no problems untill the ambient temp dropped then it would not start checked low pressure pump rebuilt the high pressure pump as the seals were leaking on the face plates changed the glow plugs checked the circut but it still would not start when it was cold done a leak back check and one injector was leaking back a huge amount, had the injector rebuilt and it now starts better than it ever has in since i got it.

 

[mersum1es]

injector leak is very common, but now OP has brand new injectors from Bosch... but it is rather easy to measure tank leak DIY, could be worth to check.

 

[jon_viola]

injector leak is very common, but now OP has brand new injectors from Bosch... but it is rather easy to measure tank leak DIY, could be worth to check.

Thanks for this. How do you measure the tank leak then? Are the seals on the main pump easily changed? Cost?

 

[mersum1es]

Thanks for this. How do you measure the tank leak then? Are the seals on the main pump easily changed? Cost?

For leak test there are commercial kits
http://www.fordwiki.co.uk/images/b/bd/Test.jpg
http://homepage.ntlworld.com/a.whetstone/volvo/f2.JPG

or you can use only pieces of correct diameter hoses (clamp freed pipes!)
http://www.mese.fi/forum/userpix/6563_paluuvuoto_1.jpg

Hp-pump seals costs also peanuts, but there is risk that it won't help of things worsen

Here nice pictorial DIY by older version pump
High Pressure Diesel Injector Pump Seal Replacement - Mercedes-Benz Owners' Forums

And info about newer version (like yours) DIY
Rebuilding a Bosch high pressure CP3 fuel pump - Mercedes-Benz Owners' Forums
CDI high pressure injection pump complete seal kit - Page 2 - Mercedes-Benz Forum

 

[jon_viola]

Ok, update time.

I've now changed the fuel pump and all the hoses that directly attach to it, plus the return feed from the fuel filter.

However the car is still not starting on cold mornings until it's done two or three complete turns.

On the plus side my mpg is great, there is no soot and lots of power.

I know that I could change the leak off pipes in the V next but at £96 a set from the stealers...

Any suggestions?

Thanks!

 

[E55_animal]

Jon did you resolve your problem ? I'm
In the same situation and no mechanic can help !?

Pm your number so we can discuss if you have got past this problem and it may well resolve mine

Thanks in advance

Flore

 

[BlackC55]

Stop bolting parts to it first. Live data with a Star WILL indicate the issue when the fault is occurring.

Has the low pressure fuel volume been measured? Has a compression test been done? Basics first!!

 

[E55_animal]

Looks looks like il have to call Black c55 to see if they can mobile diagnosis

 

[jon_viola]

Have you checked your boost hoses? They split and cause this problem. Also the O rings on the metal boost pipe from the turbo?

Leaks here cause unmetered air in the system which the car can't deal with.

Hope that helps!

 

[Trevor Webster]

copied this over from your P2644 thread

I had similar starting issues on an Audi A6 some years ago. It turned out to be a tiny leak in a fuel connection which only seemed to let air in (not fuel leaking out). Hence the fuel line had a bit of air in which auto-primed its way out during laborious starting.

An easy way to test this theory (as I did) would be to see if there is a difference between cold starts when the tank is nearly empty and car pointing up a steep hill compared with a full tank and the car pointing down a steep hill. If it starts much better in the latter scenario then this could be your problem.

This is a bit rudimentary compared to some of the suggestions on this thread but it might just give you a steer as to whether air in the fuel system is at the route of your issue.

Did you ever solve your unclearable P2644 issue?