Clk 320 oil smell

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Dec 19, 2021
W212 e350
Hi all
I have a 09 plate clk 320 cdi with 103000 miles and a full service history
I’ve been covering around 500-700 miles a week and in the past month I’ve been smelling a sort off fresh oil smell coming from the air vents upon stopping and in traffic only sometimes tho it’s not consistent
I’ve had it to 2 Mercedes specialists and they can’t find anything at all oil cooler is fine and nothing on floor or sump pan they engine seems dry as anything
Any ideas
Aye, lift the engine covers and with a good (LED) torch look at each injector for black tarring.
It wouldn't smell like fuel.

The blow by mentioned is from the base of the injector where it seats to the cylinder head. It's an easier repair if caught early.

Tbh I would expect a mechy to look there anyway.
Ok thanks
I only smells after a long run
I do around 70mph for about 50 miles then it’s country roads for 25 miles but as I’m stopping at lights after the 50 miles I can smell it coming thru the air vents and it’s quite strong
Then once I’m getting going it’s hardly there at all
Can’t smell nothing under the bonnet or out of the exhaust it’s only from the air vents
Thanks for helping
I would consider the PCV and its hoses and connections. The heater may have come adrift.
The V6 is also known for oil dripping from the air intake at the turbo spigot. That would take out the motor below eventually.
For the last one you can wipe some white cooking room tissue below it to look for wet oil, it's likely to be mucky there already though.

While the air intake ducting is off look for splits. If a newer fatter orange rubber seal has been fitted it may have flared the end and split it.
I'm getting the same smell characteristics from the split in my intercooler hose.
See thread here:
I'm going to MB today to pick up a replacement hose.
The car still runs OK.
The split is very hard to see without the most detailed examination.
Black hose / black split / black residue round the split / low-level light.
A bit like a blind man searching for a black cat in the dark.
Once I'd found it, I couldn't believe I'd missed it.

But - Yes - I am an inspection engineer.
One of the lessons in my trade - If it's important - Good light and look twice.
If it's critically important - Super-good light - Optimum viewing angle - Look three times.
The day I get my job badly wrong - You'll all hear about it !!
Yes it is a little Mucky around the turbo spigot area and mainly the pcv valve
Are these easy enough to replace?
Me again lol
It’s Taking longer to start now and blowing out blue smoke
But no smoke once running
Any ideas

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