timothymulcahy

Hi all!

I had a quick question about the PCV/CCV system on my 2014 MB E350 Convertible M276 engine. 91k miles.
I noticed that I have a medium/heavy vacuum suction at my oil filler cap. Is this normal? I placed a tissue over it with the engine warmed up and it did create a suction. I can actually hear it sucking in from the cap, like a vacuum. I have no visible leaks or fluid on the ground to indicate clogging. Engine runs strong. I saw some people saying that having any vacuum at the oil filler cap was bad, but I always thought this was normal? Am I missing something? Is this indicate of a clogged CCV system? Any insight would be appreciated. Thanks!

Timothy

chassis

Seems in the realm of normal. Do you have check engine light, misfire or missing at idle?

Read below.

https://mbworld.org/forums/glk-class...m-oil-cap.html

timothymulcahy

No CEL, misfire, or anything else. Seems to be normal. Just read some conflicting things haha. I remember thinking vacuum was normal. I have a 97 Volvo that’s notorious for PCV clogging and the telltale sign is when you put a baggie or a glove over the oil cap and it inflates, when it is supposed to suck in.

pfsantos

Late to the party, but for others stumbling upon this thread:

Some vacuum at the cap is normal. Too much vacuum is if you have trouble removing the cap because you have that much vacuum. Also, a whistling sound that goes away when you remove the cap is another sign. Usually means the oil separator at the back of the camshaft on the passenger side (left hand drive) has the small internal seal worn. Not the o-ring at the housing. That usually leaks oil if bad.