320cdi om642 bad cold start

[Andreyy]

Hello.I am new here Sry for my bad english,but i have some questions I have cold start problems with my W219 320cdi. When car stand overnight,it starts bad,cranks about 2 seconds,ant then starts ith some white smoke,like unburnt dieasel. But when glow plug indicator disapears and I wait 10 seconds,then crank,engine strarts perfectly. All glow plugs and relays is new. No fault codes,engine runs perfect. In my country one of MB mechanics says,that it may be clogged injetors. I then ask: why then if they clogged,after 10seconds wait,engine starts perfectly? He say,that in OM642 fuel system,when we on the ignition,and wait 10seconds,the injetors close the leak off,and fue dont return to the fuel tank..and then,when cranking,pressure dont goes away thro the leak off,and car starts perfectly. Its that true? Can i realy try the fuel additive,to clean the injetors? Thanks and sorry for bad english

 

[mioba]

sounds fine to me. just wait fir the GP light to go out before you crank. its there for a reason

 

[Andreyy]

sounds fine to me. just wait fir the GP light to go out before you crank. its there for a reason

I wait,until the GP light go out,i know that..it not my first diesel,i know,that i must wait,until GP light goes out But when light go out,and i start crank,it cranks 2~ seconds and starts with white smoke(like with a bad glow plugs) but when the GP light go out,and then i dont crank(wait extra 10 seconds after that) engine start perfectly without smoke. And this issue always comes after night,and no matter, 0 celsius,or +25 celsius. After the GP light goes out,i must wait extra 10 seconds,ant then start the engine,then no smoke,no long crank,strats perfectly.

 

[Rob76]

I would make sure that the starter battery is healthy / fully charged (Cold weather brings out all the failing batteries!) - if it is good, then check glow plug relay and resistance values for glow plugs; it sounds like a heat up problem.
The bit of white could be just condensation in the exhaust system that burns off with first start......

 

[robparker]

I know you said the relay is new, but if you pull the plug off it, is there any oil in there?

 

[Andreyy]

Thanks Battery is varta AGM and charged,relay and all glow plugs a brand new Its realy unburned diesel smell,and smoke comes immediately affter engine start for 1 second(a small cloud of white smoke,that smells unburned deasel) and then engine runs perfectly without any smoke and condesation( now in my country +12 celsius) Maybe here can bee a injetors leak off problem,and i must made a leak off test? But then why after extra 10 seconds engine starts perfectly.. I found in the google so much about this,and also found,that people also wait extra 10 seconds,and then starts perfectly,but dont found any answer of solved problem... My mersedes mechanic in my country says,that can be clogged injetors,or leaky(leaking to much to return line) And after my question about 10 seconds,how it affects for perfect start,he says,that in om642 injection system,after ~10 seconds,when ignition on,the injetors closes its leak off,and then fuel dont go through the backlines to the fuel tank,and then,when starting(cranking) the pressure does not fall,because the injetors a clossed,and fuel dont return to the tank.. Maybe its true? Maybe anyone have,or know,from where i can download pdf,where i can see how step by step in mersedes injection system works? For e.x bmw have this info(i founded it) how all system works step by step,from the ignition on, to the combustion of the fuel in the chamber,and with all the necessary conditions And....my mechanic says to me to try the injector cleaner,and that it often helps If no,then leak off test...

 

[Andreyy]

I know you said the relay is new, but if you pull the plug off it, is there any oil in there?

No,any oil(when changed all glow plugs,no any oil on plugs) And engine dont burn oil,runs perfectly,no smoke in anny conditions(full load,cold,hot..) no rough running..all perfect,except the cold start(if non wait extra 10 seconds)

 

[matthew k]

I've recently changed my GP's, and my OM642 starts fine immediately after the light goes out. My battery isn't very new also, I does sound like a fuel delivery issue.

 

[Andreyy]

I've recently changed my GP's, and my OM642 starts fine immediately after the light goes out. My battery isn't very new also, I does sound like a fuel delivery issue.

My all glow plugs and relay is new

 

[mersum1es]

Probably you have a leak somewhere and lines drain back to tank and therefore it takes primer pump extra 10 second to will feed lines again. Could be also primer pump issue but I think that should cause problem at full blast too when delivery for hp pump is not enough. But again, leak should be shown outside too, because these engines primer line is overpressurized. Measuring of low pressure line needs extra equipments. If you check live rail pressure at bad start I believe you will see lotsa variation there.

Injectors leaks can be very temperature related and even few seconds run may do enough heat to tighten gaps. You may try heat your injectors beforehand by heat gun (carefully) or hairdryer and try if it starts ok right after glow plug is off. Injectors do leak all the time to tank line, because pilot stage won't work without tank line. On the other hand I remember reading piezos NEEDS some backpressure to work ok, should check some wIS documents about the matter.

 

[onefortheroad]

As above , try 2 or 3 ign cycles before starting. I read the fuel leaks back from high pressure side or somewhere like that . Lazy starts are the result of no fuel being present. Common issue with the om642 of old.

 

[Andreyy]

Probably you have a leak somewhere and lines drain back to tank and therefore it takes primer pump extra 10 second to will feed lines again. Could be also primer pump issue but I think that should cause problem at full blast too when delivery for hp pump is not enough. But again, leak should be shown outside too, because these engines primer line is overpressurized. Measuring of low pressure line needs extra equipments. If you check live rail pressure at bad start I believe you will see lotsa variation there.

Injectors leaks can be very temperature related and even few seconds run may do enough heat to tighten gaps. You may try heat your injectors beforehand by heat gun (carefully) or hairdryer and try if it starts ok right after glow plug is off. Injectors do leak all the time to tank line, because pilot stage won't work without tank line. On the other hand I remember reading piezos NEEDS some backpressure to work ok, should check some wIS documents about the matter.

Thanks for reply friend If we talk about the fuel leaks,is there no any leaks to the ground and on engine(no any smell of diesel anywhere,everywhere dry). About the primer pump,you right,it also think,that primer pump cause problem at full blast and forever,not only on cold start. Now i think,i try to check the rail pressure at the cold start,when crank the engine(it should rise quickly to the 250bar,for engine start? ) Yes,injetors do leak off to the return line,ant to the fuel tank all the time,thats in all diesels,but when engine not started,and only ignition on,for me one mersedes mechanic says,that after ~10seconds injectors closes theys leak off,and when we start crank,the pressure dont drops for the moment,and engine starts,and affter start,of course,injetors starts leaking off fuel to the return line,to the tank..I dont know,thats true or not.. And one more question..for piezzo hard to do leak off test? And what about the old type glow plugs relay?Maybe it should have affect on it...


On the other hand I remember reading piezos NEEDS some backpressure to work ok, should check some wIS documents about the matter. Maybe i can see the wis off this engine,how it works step by step,and all conditions..?

 

[Andreyy]

As above , try 2 or 3 ign cycles before starting. I read the fuel leaks back from high pressure side or somewhere like that . Lazy starts are the result of no fuel being present. Common issue with the om642 of old.

I should try,but i think,result will be like with one long cycle,like now,when GP light goes out,wait about 7-10 seconds,and engine starts perfectly

 

[onefortheroad]

I should try,but i think,result will be like with one long cycle,like now,when GP light goes out,wait about 7-10 seconds,and engine starts perfectly

Only difference maybe is the fuel pump will prime twice .

 

[Andreyy]

I found one thread in another forum
https://forums.mbclub.co.uk/threads/w211-e320cdi-starting-issues-please-help.201351/
He dont reply,how he solved this issue,but hes last message about the boost pipes O-rings,and he says,that broken O-rings cause this issue. It is real? I know,that in petrol anny unmetered air cause many problems,like a bad start,jerking,rought idle, high consumption and more...but in diesel..hmm..its basically cause low power,black smoke,no boost.. But in my situation,the extra time with ignition on should have no effect,if this O-rings is bad..I think it is fuel delivery problem. I start with the rail pressure check next morning

 

[alexanderfoti]

I have seen this with some non OEM glow plugs. Does it have MB glow plugs in them?

 

[Andreyy]

I have seen this with some non OEM glow plugs. Does it have MB glow plugs in them?

Its non OEM,but its beru(as i know,MB uses beru)

 

[Andreyy]

Some update Now,when winter came,and outside temp drops...car no need extra 10seconds wait after GP ligh goes out,and no extra cranks...when temp drop to ~0 Celsius,car engien start if perfect,now temperature is -8 celcsius,the engine continues to start perfect..just wait 2 seconds when gp light goes out,ant starts.. Now my quesstion:maybe its realy bad GP control module(but it dont shows a error) because i think,when outside weather is +5 or more,the glow system not hot enough the glow plugs.. Any sugesstions?

 

[ChrissM]

Some update Now,when winter came,and outside temp drops...car no need extra 10seconds wait after GP ligh goes out,and no extra cranks...when temp drop to ~0 Celsius,car engien start if perfect,now temperature is -8 celcsius,the engine continues to start perfect..just wait 2 seconds when gp light goes out,ant starts.. Now my quesstion:maybe its realy bad GP control module(but it dont shows a error) because i think,when outside weather is +5 or more,the glow system not hot enough the glow plugs.. Any sugesstions?

Hi, did you solved the issue? I got something similar on cold start. Not 10 secs, more like 3-4secs, but still.

 

[Andreyy]

Hi. Not sovled,but from other threads,where the same issue,this is the bad glow plug relay(also,no GP light after start). In Lithuania this winter was very cold. -22~ ant when cold,GP light comes for 2-3 seconds and car starts perfectly all winter. But now when temp is +15,in the morning gp light comes for some miliseconds,and if I try start and no wait extra seconds,they do some extra cranks. I think i change the relay later in the future,maybe autumn. Because if think logicaly,this extra seconds after GP light go out may be only related to heating. 1 time I tested like this. Try wait a extra 7-10 seconds after GP light goes out,then off ignition,then again on ignition and no wait,and starts perfectly If you change the relay,post here