Leaky 850 Mk II

Hi

My Interstate is running well, but after a few miles, when I pull up, it quickly deposits lots of small patches of oil on the ground under the whole of the engine/gearbox area. I've attended to the obvious things like tacho drive and rocker box covers, but I still can't make out where the oil's coming from. It looks as if it may be exiting somewhere in front and blowing along the frame rails before dripping off - so not the breather, I think. I had a MkIII before which was completely oil-tight for many years, so this is a bit frustrating and somewhat annoying. Any ideas please?

Thanks

Trevor

I have had the same problem yesterday, bike has been oil tight for 5 years and oil is dripping off the right hand frame tube and onto the centre stand.

I did about 100 miles on it yesterday, and did clean up the bike with degreaser before setting off so i might see the problem, but it was dark when i got back and i am at work today (arrgh)!

Checked all the fixings etc, but suspect the oil tank, as i have got through 2 petrol tanks since i have had the thing and it never goes wrong by halves!

Let us know what it was.

Mike

Is it clean oil thats dripping? Definitely engine oil? 750 or 850? One place on 750's is the rear of the cases at the barrel joint. On some 850's with porous heads 2-3 fins down at the front but that is supposedly more of a damp spot than a full leak. Case joints, barrel joint, head to barrel at the push rod openings, 2 x 5/16" front studs where they break into the head inside. Other spots are the CB/camshaft seal (obvious when the cover is removed), lead entry on timing side to CB/trigger plate. Unlikely to be chaincase since you think its from the front but if the seal is going it could be overfilling the primary and pushing out oil through the 4th gear felt seal.  Timing covers don't always seal well at the bottom (mine needs sealant despite surfacing). Oil feed adaptor also a possible spot for leakage as is the relief valve. Good luck, it took me 6 years to get mine dry, now it rusts! Worth looking at a one way valve on the breather. It won't cure bad leaks but it will keep a slight seeper basically leakfree.

Just a thought, it may be from the chaincase. Oil can escape through the gearbox shaft seal, and drip down and makes a real mess. Poss check oil level in there, and if its over full, take out the timing plug/clutch adjustment plug and start the engine. If you can hear a puff puff noise then the left crank seal has gone and engine oil leaks into the chaincase, and crankcase pressure will force it out as the chaincase it not vented.  Alternatively clean it all off, and run it for a while, then sprinkle talc powder over the lower part of engine and that will show up where its coming from. You may well have to put it on centre stand and get your head underneath to see whats going on.

I have had experience of all the above. Good luck.

Thanks for all your suggestions. I think I've found the source of the leak. The two cylinder head sleeve nuts (one under each exhaust port) are missing!!! I have them on order.

Regards

Trevor

Previously wrote:

I have had the same problem yesterday, bike has been oil tight for 5 years and oil is dripping off the right hand frame tube and onto the centre stand.

I did about 100 miles on it yesterday, and did clean up the bike with degreaser before setting off so i might see the problem, but it was dark when i got back and i am at work today (arrgh)!

Checked all the fixings etc, but suspect the oil tank, as i have got through 2 petrol tanks since i have had the thing and it never goes wrong by halves!

 

Let us know what it was.

 

Mike

 

I've had this one on my IIA Roadster (twice) - the oil tank bottom fixing cracks due to poor anti-vibe mounting and you can't see the problem, just a small pool of oil. To test it I blocked all the ports on the tank and applied a foot pump to the breather vent whilst holding the tank under water (not as difficult as it sounds) - a string of bubbles shows the problem. Quick trip to local engineering firm - small plate welded around the bottom mounting - now leak free.

 

Steve

Not as bad now, perhaps, but it's still leaking. Some oil is blowing out the drain hole at the bottom of the points cover, so I'll try a new points oil seal.