Crankcase Breather (cyclone valve)


Dedicated Member
Dec 9, 2011
Hi All
I have had a problem on my 3.0i M54 for a while, of oil consumption, around 1 litre every 1000 miles. From looking on the net this seems to be expected of the M54 so I was not too worried. A couple of weeks ago I was accelerating to overtake and got a huge amount of white / blue smoke from the exhaust. James Bond would have been proud of the smokescreen! I pulled over turned off could not see any obvious damage, drove home. From searching the web popular opinion seemed to point to a blocked crankcase breather valve. The M54 seems prone to this, especially in the x5 for some reason, between 50k and 100k miles, I am on 94k. There is nothing in my Bentley manual on how to change this. Fortunately youtube came to the rescue with a three part series on how to replace the affected parts courtesy of Bavarian Autos.

I ordered the parts from Dick Lovett Specialist Cars Limited at £110 all in. This consisted of the valve and four hoses.

This is the valve in-situ, the two torque screws were a pig to get to even though they look easy here!

The old parts removed.

Nasty Mayo 1.

Nasty Mayo 2.

The parts with mayo seemed to be the valve and also the hose that went to the rocker cover. Apparently caused by condensation build up.

I cannot overstate how helpful the videos were. The air did turn blue at various stages throughout but did get immense satisfaction from completing the task.
The car started up fine on completion and was good on a short run. Will take it on a longer run tomorrow.




Global Moderator
M Power
Dec 2, 2011
Newbury, Berkshire
Model of Z
Z4 M Roadster
Someone asked what a cyclone valve was on here a week or so ago, so I guess that answers the question.

I'll copy this to the knowledgebase...