Chronic oil leakage from crankcase breather

[Bitza]

Hi all, I have a 2001 M900ie engine that I bought second hand and have run for a few hundred miles no problem. But then all of a sudden its pouring (well a regular drip-drip-drip anyway) oil out of the airbox breather pipe. To date I've tried replacing the breather valve, honed the bores & replaced the piston rings, measured bores for ovality (max half a thou). Heads have recently been refurbished including new valve guides. Have now had the slightly damaged/oval bore replated and will replace at weekend all being well, but in all truth am not holding my breath in belief all will be sorted. Has anybody got any bright ideas? can an oil pressure relief valve being stuck open or shut cause excess crankcase pressure? All/any help gratefully accepted, Bitza.

[pooh]

Where is the oil dripping from exactly?

Ian

[Shauns4]

an oil pressure relief valve being stuck open or shut cause excess crankcase pressure? All/any help gratefully accepted, Bitza.

no it can't, oil out of crankcase breather is usually due to excess crank case pressure caused by leakage past the pistons.

[The Kevlar Kid]

I've seen this on a few Monsters now. Make sure the breather is screwed in good and tight as if not it will emit a very fine spray which if not cleaned off will build up and look like a leak (even though there will be no noticeable loss of oil in the oil 'window').

Using a small amount of liquid gasket will probably also help to get a good seal.

If it's more chronic than that you do have a problem though...

[Bitza]

Ian, just to clarify where the oil is leaking from, it actually drips from the breather pipe from the air intake/filter box, which inturn is fed from the breather bottle (next to top of rear shock), that in turn is fed from the engine breather at the rear of the engine. i.e. the oil is coming from the crankcase presumably due to excess pressure?!%$* or something?

Which brings me onto Shaun's reply (thanks by the way), yes just what I thought hence measuring, honing/new rings etc. but it doesn't help get rid of the problem.

Thanks for everybody's time & thoughts Mike.

[bod]

If the engine is breathing heavy then as said above it must be worn bore/rings OR is there another breather that is blocked (and I know you say it's coming out of there) But some sort of blockage in the crankcase breather system may force oil out off all sorts of places (gaskets etc)

Obviously it hasn't been overfilled with oil (using correct sight glass window)?

[Rockhopper]

How did you run it in after the the honing and new rings? If its been done to carefully and glazed the bores that might be the problem.

[pooh]

Bitza
still slightly confused, if oil is leaking from air box end is the pipe clear into the airbox as any oil mist in the pipe should be drawn into the engine, it may be worth checking that the pipe is not split were it joins the airbox, your bike is the same age as mine and the hoses on my have started to split. I have had the other end of the pipe ie the breather bottle end split and spray oil mist all over the back end of the bike. New hose is about £37-00 but sounds like the problem.

Ian

[Bitza]

Thanks again for your thoughts, but we're not talking oil mist here this is dripping at a drop a second from the air box breather pipe, and that of course doesn't include the oil sucked directly into the inlets either. All breather pipes are clear, and I've tried reducing the oil level to the minimum shown on the sight glass too. Ducati UK did suggest glazed bores prior to honing & new rings being fitted but no result. As for running in chance would be a fine thing, short that is of towing an oil tanker, I've actually clocked up some 35 oil soaked miles to date and now have a totally water proof left boot to show for it.

I get the feeling that this isn't going to be down to the obvious or even the slightly obscure, although it may well be very simple. I was rather hoping that somebody out there might have already experienced the same thing and had found the problem and maybe even the cure too, thanks again Mike.