New to the forum and interested in some the members insight and experience.

I did quick search for other threads on this topic, some were very informative, but did not address the specific area for the leak I beleive that I have on my engine.

Quickly: '90 525i, 5 speed (m20) with 170K + miles

The area that appears to be leaking is just in front of the "oil pipe" that vent the crankcase to the manifold. I there is an o-ring that may have failed. From the EKT, the parts are as listed below.

23 NEEDLE SLEEVE 11,4X16 1 11111265412
24 GASKET RING 1 12111363190
25 BEARING COVER 1 11411276333


What is this called?
Has this been a source of leaks?
Has anybody removed the parts and replaced the o-ring?
Is this a difficult task?
What is the best technique?

Thanks in advance!