S212 E350 CDI fumes in engine bay

[Candellara]

Spent some time doing some routine cleaning chores under the bonnet of our older (2010) E350 today. Whilst the engine was running i noticed how the engine bay stunk of fumes. Our other E350 (later 2015 Bluetec) doesn't smell at all. The car was serviced a few months back and had a new red turbo seal fitted (i was told purely as a preventative measure as it's only a few pounds) but the engine bay stinks of diesel fumes (no visible diesel leaks) Anyone come across this before?

Noticeably, the fuel consumption hasn't been brilliant over the last few months. Averages 25 on shortly journeys but it really needs a very gentle right foot on longer journeys to get anything over 34mpg whereas it used to quite easily manage high 30's / early 40's

Any ideas or pointers?

[NMNeil]

High exhaust back pressure, possibly from a plugged DPF or cat.

[Candellara]

NMNeil said:

High exhaust back pressure, possibly from a plugged DPF or cat.

Emissions all normal on the car, no black smoke etc - car is all standard, fairly low miles (80k) and we've owned since nearly new but it does mainly do short journeys now. I seem to remember asking about the fuel consumption on the last service and they checked soot and ash levels but it came back as ok and no other issues reported on last major service in October. Could it be that the DPF is getting a bit choked up and it needs an Italian tune up?

Edited by Candellara on Monday 3rd January 16:58

[leef44]

Put some V-Power diesel in it and give it a long run. That should help clean it up a bit and go from there.

[Candellara]

leef44 said:

Put some V-Power diesel in it and give it a long run. That should help clean it up a bit and go from there.

Yep, i think that's first port of call. Although there's no engine management light on and the soot and ash levels are within tolerance, it could still be fairly blocked after 80k miles and the Wife only uses the car around town. Anyone removed a DPF and cleaned one out? and with what success?

[leef44]

Candellara said:

leef44 said:

Put some V-Power diesel in it and give it a long run. That should help clean it up a bit and go from there.

Yep, i think that's first port of call. Although there's no engine management light on and the soot and ash levels are within tolerance, it could still be fairly blocked after 80k miles and the Wife only uses the car around town. Anyone removed a DPF and cleaned one out? and with what success?

A work colleague had a 2.0 diesel Ford Galaxy, she did just this and it sorted itself out.

[Dog Star]

If this engine has similar issues to the slightly older 2148cc Merc Diesel engine also fitted in E classes then they have plastic fuel lines running around under the engine cover, to the filter etc. these are prone to becoming brittle and leaking.

I’d give those a check if I were you. They’re snap fittings and an easy DIY fix.

[MercedesClassic]

Sounds to me or smells to me a possible injector leak? That's if it smells of diesel. I had this on my engine.

Started off with the leaky injector sound of put put put put from around the top of the Vs where the 2x3 injectors sit. It was caught promptly but if not this leads to what's known as 'black death'

I has the injector cleaned up and reseated for about£100. It was after this that diesel smell in the cabin occasionally occurred. Long story short the injector's diesel return valve or line wasn't sealed properly and was leaking over the engine. Was fixed after 2 visits to mechanic, all FOC thankfully.

Not sure if this is your issue but check YouTube for videos to compare. Also as mentioned it could be fuel lines, joins, clicks or the fuel filter needing attention.

[Candellara]

MercedesClassic said:

Sounds to me or smells to me a possible injector leak? That's if it smells of diesel. I had this on my engine.

Started off with the leaky injector sound of put put put put from around the top of the Vs where the 2x3 injectors sit. It was caught promptly but if not this leads to what's known as 'black death'

I has the injector cleaned up and reseated for about£100. It was after this that diesel smell in the cabin occasionally occurred. Long story short the injector's diesel return valve or line wasn't sealed properly and was leaking over the engine. Was fixed after 2 visits to mechanic, all FOC thankfully.

Not sure if this is your issue but check YouTube for videos to compare. Also as mentioned it could be fuel lines, joins, clicks or the fuel filter needing attention.

I popped the engine cover off and had a good look around and there's no visible leaks anywhere. Indeed, the car had a large B service in October and a new fuel filter and nothing reported then. It does smell like exhaust gas rather than a diesel smell.

[NMNeil]

Candellara said:

I popped the engine cover off and had a good look around and there's no visible leaks anywhere. Indeed, the car had a large B service in October and a new fuel filter and nothing reported then. It does smell like exhaust gas rather than a diesel smell.

Get the engine up to operating temperature then turn it off. Wait 5 minutes then start it and immediately floor the throttle pedal. If the revs rise then start to fall back as though the engine is struggling, you have a blockage in the exhaust somewhere.
Alternatively pick up a cheap vacuum gauge and hook it up to a vacuum port on the intake manifold.

[Paddymcc]

Check your turbo seal that was replaced has been done correctly. They pinch on the underside and then the heat will warp them. Theres another red/orange seal just in front of the turbo one that i think goes to the EGR that will also leak some oil and fumes so check thats pushed in tight as well.

Keep an eye on your oil level but also have a look under the passenger side behind the engine beside gearbox for any oil leaking as its a sign of the oil cooler seals needing done. OIl pools in the V6 head where the cooler is situated then runs out a hole on the back of the engine and when warm will also get smelly. Im not sure if this issue was ever resolved with the newer version of the OM642 engine you should have.

[Candellara]

Paddymcc said:

Check your turbo seal that was replaced has been done correctly. They pinch on the underside and then the heat will warp them. Theres another red/orange seal just in front of the turbo one that i think goes to the EGR that will also leak some oil and fumes so check thats pushed in tight as well.

Keep an eye on your oil level but also have a look under the passenger side behind the engine beside gearbox for any oil leaking as its a sign of the oil cooler seals needing done. OIl pools in the V6 head where the cooler is situated then runs out a hole on the back of the engine and when warm will also get smelly. Im not sure if this issue was ever resolved with the newer version of the OM642 engine you should have.

Thanks. I'll check these seals. Oil cooler seals were done in 2020 and apparently the updated seals were fitted

[PASMERC]

You probably have a injector blowing and you are smelling combustion fumes blowing past the injector

[Candellara]

Had a good scout around under the bonnet today. Cannot see anything obvious such as an injector blowing past a seal. Car runs fine and is not down on power. No EML's or similar. Took the car for a 50 mile run today but the fuel economy sure isn't what it once was. Really being very gentle on the throttle the car only manages 31mpg on a long run whereas our later E350 BlueTec achieves over 40 and im sure the older 2011 car used to manage high 30's

It looks a bit "gunky" around the PCV valve and i've seen a couple of YouTube clips where these crack on these engines and can result in poor fuel economy. Any truth in this and could this be the cause of the fumes and poor economy?

What does anyone else get on an early E350 S212 on a run?

Edited by Candellara on Sunday 23 January 18:17

[TarquinMX5]

There have been reports of 'fumes' believed to come from the PCV. If it looks 'gungy' around that area it's quite possible that the seal etc. is past its best. They upgraded the pcv and pipe, complete with a new-style seal, part no. is **POSSIBLY** A6420101891 as the new part. The revised seal has a different clamp which should, in theory, prevent seal coming loose and being ingested.

However, please note that I cannot be sure that that would be correct part for your car. No idea about realistic fuel figures on yours.

[Candellara]

TarquinMX5 said:

There have been reports of 'fumes' believed to come from the PCV. If it looks 'gungy' around that area it's quite possible that the seal etc. is past its best. They upgraded the pcv and pipe, complete with a new-style seal, part no. is **POSSIBLY** A6420101891 as the new part. The revised seal has a different clamp which should, in theory, prevent seal coming loose and being ingested.

However, please note that I cannot be sure that that would be correct part for your car. No idea about realistic fuel figures on yours.

Part number 642 010 17 91 is the one MB list for my engine

[TarquinMX5]

My recollection is that the 'upgrade' isn't listed for all models.

The following link might give some more info., there's been much discussion/threads about it in recent years.

https://forums.mbclub.co.uk/threads/2012-c207-e350...

[Candellara]

TarquinMX5 said:

My recollection is that the 'upgrade' isn't listed for all models.

The following link might give some more info., there's been much discussion/threads about it in recent years.

https://forums.mbclub.co.uk/threads/2012-c207-e350...

Ive ordered part number 642 010 17 91 as that's what is listed for my engine number. The old plastic part is obviously not sealing correctly hence the oil misting. I'll report back with what i find

[Candellara]

Received the part from MB. The PCV valve is now alloy (i guess the old plastic variants crack & split) so hence the change. Interestingly, it doesn't have the revised clamp / seal arrangement as some do.

[TarquinMX5]

Good luck; it will be interesting to know whether the new part makes a difference.