Hey guys. I got some hose to test the breather but I'm slightly confused by the results.

Lots of vacuum at idle, it sucked the fluid up quite far. It holds fairly steady until high revs and then drops quite fast.

Is this normal? I would have thought it would be better to be higher at higher engine speeds. I have an oil leak that gets very bad on the motorway.

YouTube video for ya:

https://youtu.be/TeAmUMMtLOE

Ian,
maybe do the test the correct way, with the most relevant result being obtained when the engine is held at high rpm?
Note, 'held' not just 'blipped'...

It's the 'difference in level of the fluid' in the manometer legs you're looking for.
If the result shows a 'pressure', rather than a 'vacuum' inside the crankcase at high rpm, either the breather is u/s or there's excessive blowby between the pistons and the barrels.

Btw, best to use LHM as the manometer liquid, rather than water or Coca Cola; if LHM is sucked into the engine, it won't cause the sort of problems which those other liquids could produce.

DSC00079 by that is my real name!, on Flickr

Did the test again. The legs were dead level before I started. The difference in the two legs was 15" (A lot!) at idle, and when the revs were high it went down to 5". I just feel too bad holding it for very long at high revs.. Sorry, you cant see it very clearly on the video.

https://www.youtube.com/watch?v=_bGPxVnO7_s

There's basically nothing wrong with it, I've decided. Got great vacuum, despite the breather being about 8 years old, it was an ECAS one. Think I've fixed me leak anyhoo so it's all good. (Hopefully.)