Power Steering reservoir cap question.

[MercC350Coupe2011]

Hello everyone. I have a question to fulfill my curiosity

As I was checking my power steering fluid I noticed that the cap has a small opening on top like in the pic below.



Some other caps have no opening. Do you know what is the purpose of this opening?



thanks a lot in advance.

 

[MercC350Coupe2011]

With this opportunity can I also ask of someone knows where is the power steering filter located? I have got a mercedes c350 coupe 2011 with the m276 engine.

 

[Bellow]

Hello everyone. I have a question to fulfill my curiosity

As I was checking my power steering fluid I noticed that the cap has a small opening on top like in the pic below.

View attachment 114284

Some other caps have no opening. Do you know what is the purpose of this opening?

View attachment 114285

thanks a lot in advance.

At a guess, a vent. Just to allow for expansion and contraction of the air space above the oil.

With this opportunity can I also ask of someone knows where is the power steering filter located? I have got a mercedes c350 coupe 2011 with the m276 engine.
View attachment 114289

Not sure if MB fit external filters in their PAS systems. I think what you are looking at is a retro fit filter.
I've just fitted similar to my (non MB) PAS and as per the instructions, only to be fitted in the low pressure return line. Mine are rubber so an easy cut, shorten, and fit. Steel lines will be a tougher proposition.
Unless someone comes along and says otherwise, I'm guessing your car doesn't have a replaceable filter as standard.