Sprinter CDI smoky at idle

My 220k mile '02 Sprinter 311 CDI has recently become quite smoky at idle when hot. The smoke smells like unburned diesel (not oil) and the problem has gotten gradually worse over the past 10k. Once you get going the smoke clears within a few seconds. The colour of the smoke is blue/grey.

It doesn't really use any oil between the oil changes (maybe half a liter per 10000 km) and the fuel consumption has stayed the same. Doesn't lose any coolant, Idle is smooth and there is no smoke on the run including full load and the power feels great. The engine also starts well hot and cold. What do you reckon causes the smoky idle?

Forgot to say that the engine type is OM611(.961 maybe) and it's the first generation Merc common rail engine. The 311 of that age does not have a cat, DPF, or EGR.

biko

Perhaps start with a fuel system cleaner and see if that helps.

biko

biko wrote: »

Perhaps start with a fuel system cleaner and see if that helps.

So you are thinking it's fouled injectors, which I'm suspecting too. Would you have any recommendations on suitable cleaner?

biko

Yeah possibly.
About cleaner, a name brand like Redex Fuel System Cleaner should be good to start with. Make sure to get it for right fuel type.

rex-x

Commonrail injectors don't get fouled as with older injectors, they run at 30,000 psi which makes it very hard for anything that redex would shift to foul them up......
I would suggest a leak off test and go from there

rex-x

rex-x wrote: »

Commonrail injectors don't get fouled as with older injectors, they run at 30,000 psi which makes it very hard for anything that redex would shift to foul them up......
I would suggest a leak off test and go from there

Cheers, I contacted Diesel Injection Services in Tipperary that can recondition common rail injectors and they sounded very promising also mentioning the leakage. Going to drop and leave the van there to see what they'll find. Cheers!

fancy pigeon

Hows the injector washers?

fancy pigeon

fancy pigeon wrote: »

Hows the injector washers?

The last time I checked there was no sign of black death so hopefully it will be easy for the garage to remove and test the injectors.

fancy pigeon

samih wrote: »

The last time I checked there was no sign of black death so hopefully it will be easy for the garage to remove and test the injectors.

Do you notice the injectors a bit chattery up the revs? Injectors are worn on my 220, the injectors are a bit chattery. There's a puff of grey smoke now and again (rare)

Love the way there's no EGR on your engine, those things are a disaster!

fancy pigeon

fancy pigeon wrote: »

Do you notice the injectors a bit chattery up the revs? Injectors are worn on my 220, the injectors are a bit chattery. There's a puff of grey smoke now and again (rare)

Love the way there's no EGR on your engine, those things are a disaster!

I can't say I have heard any difference on the sound. There has always been a bit of a clatter just when the boost kicks in around 2.5k or so but I have always written this down as "character". Mind you the van already had 170k when I bought it so plenty of time for previous wear and tear.

Yeah, I disassembled the inlet manifold a couple of year ago to change the glow plugs and it looked totally clean thanks to no EGR. But don't tell Al Gore about the resulting NOx emissions.

OK, time for a follow up.

The van has been idle all winter but I finally got around getting the injectors sorted out before the season starts. Used a diesel injection specialist near Blanch and they did a really good job reconditioning the old injectors. Then van was with them for two days. All four injectors needed new plungers and tips alongside seals and the engine now sounds very smooth. All the smoke is gone apart from a bit of coal at full blast as expected without DPF. The acrid smell at idle is gone too. In retrospect the old injectors sounded extremely clattery in comparison.

Will be interesting to see if there is any difference in fuel consumption. There was no sign of leaky injector seat seals in my engine.

biko

Sound, thanks for updating