Novel engine breather???

[lancialulu]

I wonder if anyone can shed some light on this non-standard (?) addition to an Aprilia Cambox cover??

It could just vent to air like some early Fulvias saving the oily mist that covers the bulk head after a long fast run??

All input welcome.

I should add that the top of the vertical tube is open to  I assume take the normal rocker cover cap.

Tim

[ColinMarr]

It never happened for me, but I heard stories of a build-up of petrol fumes under the rocker cover being ignited by faulty plug connectors – the resultant explosion firing the filler cap directly upwards with some force to hit the underside of the bonnet. I remember seeing bonnets with a small raised dome in exactly that position! My guess is the device you have is an attempt to deflect any explosion and flame to somewhere else!

Looking forward to reading about your impressions of driving your Aprilia.

Colin 

[ben]

         Presumably it goes on a bit further than in your pic.
         If one of the fabled explosions occured the cap would probably still thump a dent in the bonnet so I suspect it was a personalised mod to vent a heavy breathing engine into the carb. intake.
         Considering the explosion scenario I don't see how petrol fumes can get into the cam-box. I think it must be the oil mist that lights up if the oil/air ratio happens to hit the spot as it were! Strangely it has never happened to me in 47 years of Aprilia motoring despite frequent misfire problems due to faulty plug connectors.
                                                                                           Ben

[lancialulu]

Ben - yes bottom bit with the holes goes all the way into the cam cover.

It doesnt look "homemade" at all hence I thought there should be some other experience out there.

Tim

[Scarpia]

canI have one please... .i have experienced several explosions and often have quite a lot of onderbonnet fumes.

[fay66]

With a bit of stainless wire wool in it,  it would make a good flame trap!

Brian
8227

[BlueSky]

Amongst the spare bits I have there is also another variation on a breather set up. I think it's missing something as the cap on the chain doesn't fit in the top section.

Noel

[davidwheeler]

Nothing fabled about the explosions.  (Bang! ting. cabin fills with smoke).  I had a few with my home made plug connectors using exposed (Peugeot) metal connectors - no chance much for a spark I thought but I have cured it (d.v.) by enclosing the connectors in plastic hosepipe.

[lancialulu]

Has anyone got one fitted to see?

I assume a hose of some sort attaches to the side pipe and breathes to atmosphere below car?

Tim

[Andrew Cox]

Angelo Catalano, a local (Melbourne, OZ) Aprilia owner of over 50 years, has a similar arrangement on his car. The hose from the breather runs to the airfilter, but I do not know if a PCV valve is fitted. Paul Vellacott (another local) who has also owned his Aprilia for close to 50 years reckons the explosion problem is caused by worn  springs in the spark plug connectors. His solution is to fit a short piece of copper tube to the top of the spark plugs to increase the spring tension. The only time he has experienced the explosion problem in recent years, is when he forgot to reinstall the copper tube after servicing the car. It occurrs to me that the brand and height of the spark plug may contribute to the problem.

Andrew

[davidwheeler]

That would not explain my explosions which occurred with a very positive connection to the plugs but I suppose I had such good power from my coil (a beautiful glass pot filled with oil in which the coil resides)  that a spark was jumping to some nearby bit of valve gear.  I have got some original connectors, perhaps I should try Paul's mod (I made my own because of persistent misfire believing that the spark was "leaking" through the cracks on the side!).