Mysterious oil dripping on my loop

[bigbikerrick]

Hello Folks, the other day, I put my 73 eldo on the centerstand which I rarely ever do, and when I come back to it I find a 2" diameter puddle of oil, dripping from the rear edge of the front fender, and looking further, I see its coming out of the little hole on the bottom of the steering stop, and dripping onto the fender.
Further investigation, removing the fuel tank, revealed the source. I have a transmission vent hose coming up to the backbone of the frame, about 18" long, and It looks like oil worked its way up the hose,and accumulated in the "tray" or channel that makes up the frame.
  Apparently ,putting the bike on the centerstand, caused the oil to flow forward, since the rear of the bike is lifted, and then drip out of the hole below the steering stops.

I have no idea why oil decided to migrate up the vent hose, after running it this way for over 15 years, without previously  noticing any oil coming up from the vent.
Rick.

[Antietam Classic Cycle]

You might consider adding a small catch bottle on that hose. It's also safe to reduce the oil fill to 700 cc vs. 750 cc.

[bigbikerrick]

Thanks charlie. Both excellent ideas.I am going to drain/refill with 700 cc. I have also added a bit longer hose and routed it better, going a bit higher on the frame. If that does not take care of it, I will add a catch bottle.
Rick

[pehayes]

Unlike the engine, there isn't any real 'pressure' inside the transmission box.  There is a puddle of oil at the bottom and the lowest gears reside in that puddle.  As the gears turn, the teeth 'lift' oil and transfer it to gears higher up.  As they spin the gears do 'fling' some oil away but there isn't pressure.  Hard to imagine pushing any oil up 18" of hose.  Have you used the same brand of gear oil all these years?  Some brands of oil are more prone to making foam than other brands.  Perhaps experiment with a different brand?  The internal circulation can lead to foaming like dish soap suds.  If those bubbles  have a very strong surface tension they might stay as bubbles and gradually rise through your hose.  Any way to cut off  half the hose and then replace the missing half with a larger internal diameter?  The larger ID would promote breaking of the bubbles and allow the liquid oil residue to drain back to the box.

Patrick Hayes
Fremont CA

[bigbikerrick]

Thanks Patrick for the suggestions. I am currently using Amsoil synthetic gear lube in the tranny. The same stuff has been in there for about 3-4 years. I have never noticed it "bubbling up" through the vent hose, but its possible, that any discharge was staying in the rear part of the frame channel, and accumulated, then running forward ,and out the drain hole near the steering head.  I am going to try your suggestion of a larger ID hose, makes sense to me. I also plan to use some clear hose, instead of black rubber, so I can  possibly monitor if any oil is working its way up the hose. I was also thinking of trying some of the redline shockproof heavy gear oil, I have on the shelf, along with the reduction to 700 cc as suggested by Charlie.
Thank you
Rick

[glenm64]

Unlike the engine, there isn't any real 'pressure' inside the transmission box.  There is a puddle of oil at the bottom and the lowest gears reside in that puddle.  As the gears turn, the teeth 'lift' oil and transfer it to gears higher up.  As they spin the gears do 'fling' some oil away but there isn't pressure.  Hard to imagine pushing any oil up 18" of hose.  Have you used the same brand of gear oil all these years?  Some brands of oil are more prone to making foam than other brands.  Perhaps experiment with a different brand?  The internal circulation can lead to foaming like dish soap suds.  If those bubbles  have a very strong surface tension they might stay as bubbles and gradually rise through your hose.  Any way to cut off  half the hose and then replace the missing half with a larger internal diameter?  The larger ID would promote breaking of the bubbles and allow the liquid oil residue to drain back to the box.

Patrick Hayes
Fremont CA

This ^
I have owned my T3 for over 40 yrs and never had an issue with the gearbox breather hose dripping oil.
Last year I rebuilt it due to needing new 3rd gear and dog.
After rebuild it dripped oil from breather. Didnt matter if I dropped oil level, ran synthetic, rerouted breather line higher, nothing would stop it dripping from breather. I have no idea why. It did my head in.
I did what Patrick has suggested and plus some course stainless steel scourer pad in the larger section. Being course it cant move down the smaller hose. It hasnt dripped since, and it is running normal oil level. If I ever have to go back into the box I will put the vent at the back of the box like in the later model like my 1100 Cali where it is not above a rotating gear.
Many years ago I opened up the engine breather box and also filled it with course stainless scourer. Never had an issue since with that dripping either.
Think it gives a large surface for the oil mist to collect and return to liquid form and drain off.

[bigbikerrick]

Thats very interesting GlenM. so you have a smaller diameter hose initially exiting the breather, then hooking up to a larger diameter hose, which is filled with the mesh? How long did you make the complete hose?
thanks
Rick

[glenm64]

Its the normal sized hose out of box to below frame under seat and had some hose that was a tight push fit over it. Maybe 3-4" void filled with the scourer. Then it vents back down near swing arm. I did think of also putting in an inline mesh type fuel filter to do the same thing, but its working and the filters I saw were too bulky.
Still dont understand why it changed after the rebuild though. I just put it down to being Italian  Maybe one of the brains trust might have some ideas?

[normzone]

" I opened up the engine breather box and also filled it with course stainless scourer. "

Some moonshiners use copper scourer in the early stage of their output flow - Now if only you could design a Guzzi that produced ethanol !

[pehayes]

Some moonshiners use copper scourer in the early stage of their output flow - Now if only you could design a Guzzi that produced ethanol !

Its an Italian art and it is called 'Grappa'.  I have a library collection of some very fine ones.  Come to the National and I'll share a nip with you.

Patrick Hayes
Fremont CA