engine breather hose?

[philwarner]

When I pulled my gas tank from the 1996 California I found a disconnected hose between the carbs that runs to a bib on the front of the frame backbone tube.  There are two hoses that run from the cylinders on each side to bibs on the frame cross tube above/behind the carbs.  Is this some kind of breather system that might have gone to the original air cleaner box? (My carbs have individual filters now) The fitting on the loose end looks oily so I thought is might be a breather of some sort.  The last photo shows both ends of the middle hose.










names ending in u


I need an education on what these hoses are supposed to do and whether I need the one that was loose between the carbs and if the bib on the front of the frame can just be capped.  This bike continues to be a learning experience, what with a number of changes, bodges, loose electrical connectors, ect.

[Antietam Classic Cycle]

The loose hose connected on the front side of the original airbox. I'd at least put some sort of "breather filter" on it. Something like this:

[philwarner]

Are the heads sucking air through that system of hoses or was the engine sucking air through them via the air box?  I.E., which way is the air in the hoses going? (assuming it is air that they are designed to take care of).  Is this system sort of like a PCV valve on a car?  Is this a sort of crank case vent?  I can't get my brain around the function and intent and the use of the frame tube as part of the conduit.  Another Guzzi mystery to me.

Edit:  I found this in another thread describing the system which I assume is like my Cali's system:

The breather plumbing on the V7II is diabolically clever.  The top frame tube acts as the oil separator.  Blow-by from the valve covers is piped into two ports towards the middle-rear of the the top frame tube, which slants downward toward the rear.  At the very rear (lowest part) of the frame tube, a port drains the precipitated (recovered) oil in the blow-by stream into a hose that flows through a check valve and then into the rear of the crankcase.  At the front (highest part) of the frame tube is another port, which coveys the (mostly) oil-free separated air to a hose that leads to what formerly functioned as the oil separator, molded into the front of the air box.  In the previous 1-TB models, this oil separator had one input hose coming from each valve cover and two oil outlets, which merged with a Y connector, and then onto the check valve and rear crankcase oil return port.  However, on the V7II, three of the ports on the former oil separator are blocked off with rubber 'nipples" and the remaining port takes the blow-by air hose coming from the front of the frame tube.  The only way out for this air (which still contains a small amount of oil) is through a small orifice between the former oil separator and the air box proper.  Thus the blow-by air is eventually taken into the engine air intake stream.

Other comments were:

There's a *lot* of oil vapor in the small block breather system coming through the pushrod ports.. it's essentially how the top end gets lubed.

You want to use a filter because the air moves in both directions, so it can suck in stuff.


Do these comments sound right for the Cali?

[Antietam Classic Cycle]

Are the heads sucking air through that system of hoses or was the engine sucking air through them via the air box?  I.E., which way is the air in the hoses going? (assuming it is air that they are designed to take care of).  Is this system sort of like a PCV valve on a car?  Is this a sort of crank case vent?  I can't get my brain around the function and intent and the use of the frame tube as part of the conduit.  Another Guzzi mystery to me.

The frame is being used as a breather box. The hoses from the heads and the larger "S" shaped hose are all venting into the frame. The loose hose with the fitting was attached to the lower front of the airbox and the frame vented through it. Inside where the large "S" hose attaches to the engine, there should be a ball-type check valve. I've seen them stick shut and I've seen them with the ball rusted partly away. While you have the tank off, it would be a good idea to remove the hose, put the check valve out of the tube and inspect it.

[philwarner]

The frame is being used as a breather box. The hoses from the heads and the larger "S" shaped hose are all venting into the frame. The loose hose with the fitting was attached to the lower front of the airbox and the frame vented through it. Inside where the large "S" hose attaches to the engine, there should be a ball-type check valve. I've seen them stick shut and I've seen them with the ball rusted partly away. While you have the tank off, it would be a good idea to remove the hose, put the check valve out of the tube and inspect it.

Is the "S" hose inside the air box?  or from frame to crankcase?  I'll have to look.  The bike came to me with no air box and individual filters on each carb intake.

[Antietam Classic Cycle]

Is the "S" hose inside the air box?  or from frame to crankcase?  I'll have to look.  The bike came to me with no air box and individual filters on each carb intake.

The "S" hose connects to the top of engine at the "bellhousing" (just in front of where the engine and transmission meet) and connects to the frame just behind the steering head. It's the larger one in your photo here:

[philwarner]

The "S" hose connects to the top of engine at the "bellhousing" (just in front of where the engine and transmission meet) and connects to the frame just behind the steering head. It's the larger one in your photo here:

OK, thanks.  I was expecting the return to be farther back on the frame tube if it drains oil back into the sump.  What an interesting setup.  I'll get a filter for the end of the hose that went to the air box and call it done for now.

[kfz]

I changed the whole breather setup. I found the head to frame and frame connection laughable , the whole lot just filled with a water. you might not need such drastic measures if you live in a dryer climate than pomme land.

In the end I changed all of it.

https://www.youtube.com/watch?v=g1k6tz_Eq_0

Kev

[philwarner]

I changed the whole breather setup. I found the head to frame and frame connection laughable , the whole lot just filled with a water. you might not need such drastic measures if you live in a dryer climate than pomme land.

In the end I changed all of it.

https://www.youtube.com/watch?v=g1k6tz_Eq_0

Kev

I am looking at your video.  Should there be sound?  I Think I'll keep mine mostly as is and add a filter to the line that went to the now long gone air box.

EDIT:  false alarm - my laptop speakers were intermittent and I had to reboot to get the sound back.