S320 CDI W221 intermittent starting problem

[DogmaI]

Hi All,

This is a great site and I thought I would write my first post to get some help from the experts on this forum.

I am experiencing intermittent starting problems with my S class. Eight times out of ten it will fail to start first time. After turning the key in the ignition (and holding) the engine with crank/turn but then cut out before cranking again and eventually starting. It has never failed to start but can take up to five turns/cut out cycles before starting. This happens irrespective of whether it is a cold or warm start.

So far the mechanic has tried the following:
- Replace the relay
- Replace the crankshaft sensor
- Tried starting using the spare keys to ensure there wasn't a problem with the main key.

None of the above has worked. Any advice would be gratefully appreciated.

By the way, not sure if it is a related issue, but I have noticed the gear change to be a little lumpy/jerky at times, especially in lower gears.

Vehicle details: S320 CDI, W221, 54K miles, 2007 model

Thanks in advance

 

[mbenz1]

Could be a glow plug module problem or glow plugs, pretty common in V6 CDI. its definately recommended to get a STAR Diagnostic check done by a mercedes specialist or mercedes-benz dealer, instead of trying new components...

 

[Russelld]

Hi there, I am having the exact same issues with mine, I've changed glow plugs as light was on although left 1 in as it was turning and changed glow plug control unit, star machine is not picking up any glow plug fault now. Changed crank and cam sensor, star was showing low voltage so I have changed both the starting battery in the front and the supply battery in the boot behind parcel shelf, one thing I did notice that the battery in the boot was the wrong one but now has correct one and still it has made no change. Car goes to start and just doesn't catch and sometimes cranks over and over then fires up. I've had it mentioned about timing chain could be stretched but this was replaced on my car at Merc dealership 40k miles ago 1.5yrs. Also vehicle runs fine when running. I'm stuck with this and sick of replacing part after part to no avail. Vehicle is a chauffeur car so very important to get this fixed quick. Any help would be greatly appreciated. Thanks Russell

 

[mersum1es]

Model year, engine (same as OP)?

 

[Russelld]

Hi there same as above S 320 CDI 2006/7 it has 129k miles.

 

[Russelld]

Could it be the fuel pump? Or fuel pump relay? Where is the fuel pump relay on the s class 221

 

[Russelld]

Or would the fuel pump relay show up on the STAR as faulty?

 

[mersum1es]

Usually CDI engine starting problems are fuel pressure related (if CPS is ok). Also it's worse when cold when CPS fails when engine warm. Low starting pressure reading can be detected when plugged in star, and there is test procedure for fuel quantity valve which rarely fails too. Also I remember couple of times when primer pump has caused trouble. Finally but not least return leak of injectors should be measured.

 

[vereivalu]

ML270 CDi Auto 2005

Hi this is also my first post and have the same problem as above, currently the fuel filter has been changed and all glow plugs have been replaced, it started initially from the garage but then left overnight at home and this morning would not start again cranking but failing to start

 

[wongl]

When I had starting issues with my W210 320CDI a few years ago, it turns out to be the plastic fuel pipe leaking. Interestingly, this problem started before I could detect any smell of leaked diesel - in fact I lived with this problem for over two years before I started detecting the smell of diesel which led me to investigate the plastic pipes and it was then I found that a couple of them was weeping ever so slightly. This must have caused an air bubble in the system causing long starting cycle.

 

[Russelld]

Well we have been checking the car all day, swapped glow plug module just to check, stripped and cleaned throttle housing as was soaked with oil from a leaking seal from a breather hose, which has been changed, checked all fuses, still the problem is there!
Can anyone on here contact dogmaI the originator of this thread to see if he got to the bottom of his problem?

 

[Russelld]

Also just to add. Problem seems to be getting worse rather than the same, ie it now no longer sometimes starts 1st time off the key now you have to hold the key to keep it cranking then it fires into life.

 

[Russelld]

Can anyone on here contact dogmaI the originator of this thread to see if he got to the bottom of this problem?

 

[Russelld]

I also had a new port shut off motor fitted (manifolds and flaps were fine) to my car around the time the glow plugs were done, the problem occurred after these things were done.

 

[Russelld]

Any ideas folks?

 

[Terry_]

You most likely have an injector leaking off too much fuel. Finding more and more of these now on the V6 engines

 

[Russelld]

Hi folks, it turns out the problem was the timing chain, it was stretched, that's the 2nd chain in 2yrs, luckily mine was still under dealer warranty so didn't cost me a penny this time, so folks - problem solved - timing chain!
Dealer has no idea why this has happened.

 

[E270 Owner]

Thanks for coming back and posting the cure

 

[Virusuk]

had the same with timing chane

 

[Steven1973]

Hi there

This is my first post here - very useful site - loving it.

Quick question for you guys that came back with the Timing Chain asnswer - was this picked up in a diagnostic test before replacing work was it by chance after replacing other parts, thus the process of elimintation..

I'm only asking as I recently got a C270 CDI 2002 estate and it was fine for the first couple of weeks then the 'not starting first time in the morning' thing started. The chap I got it from said it had been sitting for a few months - but started fine when I test drove it - but you could tell by the dirt etc that it hadn't moved in ages.

Is it possible that the car, now being used regularly for 3 weeks, could develop a timing chain problem after sitting for a while. It says my next service in in 13000 miles (i think).

Just wondering if me taking it for a diagnostic may show the timing chain as a fault or should I mention this threat to the mechanic..

Thanks for all your input

Steven

p.s. It is occasionally also showing an EPC fault after Kickdown.