Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > Sport Touring: ST4 / ST3 / ST2 > incontinent ? surely not !

[John W]

Hi all,
Here's one for the mechanics out there.

My ST4S has started to breath a little oil, such that when I stop after a spirited ride I get a small puddle of oil under the airbox breather.

Its just had its 36k service, and a number of the clearances were out. I was told that this can cause them to breath heavy. I took this with a pinch of salt but apparently the mechanic was told this by two sources (baines and protwins).
I've not ridden it too far since the service, so can't say if the clearances have helped. Will know soon enough though as we're off to the Alps on it on Sunday...

He checked both compressions and they are fine.
Apparently the air filter was very dirty, not sure how that would make a difference though.

It just sounds odd to me that valve clearances could cause heavy breathing (from the engine )
Any ideas ?

Cheers,
John.

[ratchet]

given breather vents to airbox, if the air filter was exceptionally blocked, it's possible engine was trying to draw air from crankcase due to filter restriction, which would cause excess oil to build up in airbox. But guess you have probably already found out if fault fixed or not

[John W]

sorry, only just seen your reply (didn't show up on 'todays posts' ).

Well the air filter is now lovely and clean and it still does it, to a lesser extent though.
i think the post on the 996/998 forum (*) is closer to the mark. That suggested the oil breather in the top/back of the crankcase gets a bit clogged and stops the oil returning to the crankcase.
(I think, might have been elsewhere).

It is an odd one. The bike runs great and has loads of compression, just breaths a little.
Thanks for the thought though.