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Registered
1997
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9 Posts
Discussion Starter #1
I opened my bonnet yesterday and found that the breather hose is wet with oil mist.

Any one can shed some lights on this?

IMG_5315.jpg
 

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Outstanding Contributor
2002 ML320, 2003 A160, 2002 ML500, 2018 GLS350d
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4,374 Posts
I haven’t studied this engine at all, but I suspect that tube isn’t a breather, but an emissions control component that returns crankcase gases to the inlet manifold for combustion.

When you remove the ECM/MAF sensor assembly, you will find the inside of this tube wet with petrol. Blow-by gases get mixed with oil vapour on their way back to the throttle valve.

Your tube is probably cracked somewhere at the clamp end.

All of the above could be totally wrong. I just fix the car when it goes wrong.
 

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W168, W169 Moderator
A180 CVT, A170, A190, B200
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465 Posts
The wet hose doesn't look bad at all, just wipe it clean if you like.
However, the breather itself is inside the rocker cover and when that gets blocked the engine will struggle to breath through other points, like dipstick, oil filler neck and throttle body, resulting in rusty dipstick, dirty throttle body and beige residue in filler nick and cap. This is more common in A140 engines more than any other models because they suffer from poor breather system. You can remove the rocker cover and clean the breather with an air blower and you'll need to clean the throttle body inside out.
 
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