pressurised fuel tank?

[slav4o1]

has anybody noticed that when opening the fuel cap pressure gets released is that normal cheers

 

[ms500]

Yes my W124 does this aswell.

 

[BTB 500]

IIRC it varies, some cars have a vented fuel system that doesn't build up pressure in the same way.

 

[kth286]

How do you know it is not vacuum ?

 

[nick mercedes]

IIRC it varies, some cars have a vented fuel system that doesn't build up pressure in the same way.

A proper vented MB fuel cap is essential, and there's enough preasure to implode the fuel tank (which does happen often - surprisingly).