Question on griso blow by return line

[lucian]

I am wondering if the line from the blow by tank to the rear of the sump is just gravity return or does it pull vacuum? I removed the tank and all the lines and flushed them out. Had some mayo crudd in two breather lines to the rocker boxes but not to much in the tank itself. And the return to the sump looked clean. Just trying to completely understand this blow by system. I started out to check the alternator belt and ended up here. One of those,   while your here you might ass well.  thanks  Dave

[Vasco DG]

System is very simple. All excess gas is vented from the engine through the two hoses that come off the plates over the end of the cams at the back of the heads. On the end of the cams outboard of the sprockets there is a flinger ring that disrupts the gas-flow so the bigger lumps of particulate oil are centrifuges out and will stick to the inside of the cases. The gas, along with particles small enough to be carried with it, is expelled up those tubes into the separator box behind the steering head. There the oil droplets will hopefully condense and drain down to be returned to the sump via the hose to the back of the sump. Gas is expelled into the airbox, which should be under a slightly negative pressure compared to atmospheric, and is re-breathed through the engine to burn any remaining hydrocarbons.

Sump return is simple gravity. How would you create a negative pressure below the oil level in a pressurised case?

Pete

[lucian]

Thanks Pete, I appreciate your response. I want to make sure the system is working optimally, so first I wanted to make sure that I fully understood how it works. Mine had a baffelectomy performed by the po and the line that once ran to the canister is now left open ended. Should this be plugged so the separator box can remain at less than atmospheric pressure?

[Vasco DG]

We don't have the charcoal canister here so I'm not familiar with it but I didn't think it had anything to do with the condensor box?

Pete

[lucian]

Thanks again Pete,  The condenser box on my griso has four lines connected to it. Two to the cam box vents, One return to sump and one long one terminating under the bike where the charcoal can used to be. If I get the motor hot enough I will sometimes notice the mayo dripping from that line. So it leaves the condenser box open to atmosphere and I am wondering if that may reduce the effectiveness of the system. I do not know if it ever connected to the charcoal can or not, but if not is this open line present on griso's without the charcoal can? Hate to be a pain, I just am not convinced that the blow by system is working properly. Thanks again  Dave.   P.S.  Is that stelvio back to life yet?

[Vasco DG]

On models without the canister the breather to 'Atmosphere' goes to the airbox. I can't see why it would be connected to the charcoal canister although that is connected to the manifolds to draw low pressure.

I think I'll have to look at the parts diagrams. Bear with me.

BTW, your cooler cover worked like a champ last weekend. In pouring rain on a freeway drone oil temp remained at 120*C ;-T

Pete

[lucian]

Pete ,  my best guess is that the line I am questioning, at one time may have routed to the air box. Perhaps they disconnected it to avoid oil and mayo ending up in the throttle bodies. It is the only way I can see the oil separator box connected to intake vacuum to recycle oil vapors. I haven't checked the air box yet to see if there is a capped off hose connector. That will be my next investigation. It would explain my thoughts since the beginning about the cambox vent system not functioning as efficiently as it should. Perhaps without the negative pressure provided via the air intake, there is no draw into the oil condenser box, thus I am seeing mayo inside the tubing , but very little inside the box. Also I never have any oil in the drain lines from the air box.  Just a guess, I have been unable to find a plumbing schematic.      Dave