Major oil leak.

[Gazbrown]

2000 ST1100 back on the road after quite a break, rode 60 odd km on highway no issues, pulled up in small town to change gloves, and the right hand side of the bike literally dripping in engine oil and oil light coming on. Right hand pants leg and boot covered, and entire right side back to the rear wheel.....glad I stopped. Pulled some of the plastic off, but far too much oil to identify any culprit, and no way to clean anything to check further. Will trailer home, but before that,  can anyone out there shine a bit of light on this. It is a massive leak, and seems to be coming from high on the front right hand side.......thanks in advance.

[Brock]

Could it possibly be a loose oil filter?? there isnt any where on the right side for the oil to come from, apart form a rocker cover or a catastrophic hole....

[Gazbrown]

Oil filter on left, and no oil that side....its got me tossed! On reflection it could be a small consistent leak and continued for the whole trip, but there is no oil where the bike is normally parked......so something let go during the trip. Just another task for me! Will trailer it home tomorrow or Friday. I have a second parts bike here and pulled the plastic off it to see if anything obvious struck me but as you say there's nothing there to leak like that! Time will tell. Thanks.

[DaleAP]

I'm guessing the valve cover gasket has said goodnight.

[Gazbrown]

I'll be happy if that's all it is!

[Gazbrown]

Thanks guys, rocker cover gasket leak. High on the rear of right hand cover.......now for the cleanup and replacement!

[Gazbrown]

Further to this valve cover gasket leak.......
Took the gasket out, cleaned it and looked for obvious splits cracks etc, found none, cleaned thoroughly and replaced with help from a thin film of permatex gasket sealant. Let sit for 48 hours, and took the bike for a run.
Lost a huge amount of oil. The half moon part of the gasket nearest the oil cap has pushed out from between the cover and the head, and that is where the leak is.
So my question is what sort of pressure is there inside the valve cover to manage to push this bit of gasket out?
Is it possible to have a blocked oil return to cause this?

Thoughts welcome.

[Brock]

There may be a blockage in the crank case ventilation line.. I have never heard of this bung being forced out before, definitely not a usual happening..

[Gazbrown]

Thanks Brock.
I am assuming the ST1100 has a gravity return for the oil, so I might try running it with the filler cap off and see if there is any back up of oil! I should have taken a photo of the pool of oil under the bike when I parked it.......was VERY substantial, and would seem to me to being forced out rather than just dripping through.
 I will investigate the ventilation line though can't imagine what might cause a blockage...
Fun times, thanks for the reply.

[Brock]

I think the crank case ventilation goes into the rear of the aircleaner, there should be a small rectangular port with a filter membrane there (looks like a bit of scotch brite)  . Its been a while since I had a look, and my bike is parked up for the next 3 months while I go on holiday, so I wont be taking it apart for a look..

[Gazbrown]

Culprit identified.
Me.
Having replaced carbs some time ago, I kinked the rubber crankcase vent line under the air box. Consequently presurising the crankcase! The line goes into a port on the right underside of the air filter housing.
All rectified now, just have a cleanup to do!

[Brock]