Oil trap, Crankcase breather
 

The oilfilter housing for the D5244T5 comes intergrated with an oil trap/crankcase breather. If you remove the black plastic top from the breather, what's inside the housing? -Is it empty?
I ask since the vacuum in the crankcase isn't great. It shows a very slight positive pressure so I'd like to fix it before it gets excessive.
If the housing is just an empty chamber there's no need to buy more than the plastic part sitting on the top.

The aluminium housing is indeed empty, the plastic cap contains a diaphragm which in my car had aged over the previous 190k miles. I think the new cap/diaphragm was about £25 3 or 4 years ago when I replaced mine.

Thanks for replying.
The crankcase breather valve can be had at skandix.de for 30 euros.
Getting it off the housing without removing the inlet manifold seems quite impossible, but since it will be necessary to clean the housing anyway it seems like it's possible to remove the whole housing without removing the manifold.