Air beathed out from the oil breather pipe (350 Scrambler 1974)

[Rocla]

Hello, my Scrambler 350 Ducati (Mototrans) 1974 has a restorated engine and a low mileage (1500 km) but I am surprised to discover a significant air flow from the oil breather pipe. Is it normal?

[Duccout]

Hi Rocla,

If it is only air that is being blown out, then I think that this is normal, but if there is oil mist being blown out then something is wrong.

Cheers,

Colin

[IanHood]

Depends how much it's blowing - a gentle puff is normal but if it's blowing a gale then rings not sealing well is typically the issue. But as Colin says, if the air isn't accompanied by much oil mist you are probably OK.

Ian

[Rocla]

Many thanks Duccout and IanHood, it blows but not that much and it is absolutely dry (no oil at all,fortunately, given the piston and rings are new).
Claude

[Duccout]

Hi Claude,

I would not worry then, just keep an eye on it in case any oil starts to spray out.


Cheers,

Colin

[Eldert]

sound like a ring sealing problem

what brand piston did you fit ? a Wössner from Jesus Guzman ?

Eldert

[Duccout]

Eldert, do you have a negative opinion of Wossner pistons?

I am no expert, but I have found that the three-piece oil control rings to be much better than the one piece, but maybe it was coincidence? Any one else?


Cheers,

Colin

[Rocla]

Pistons and rings are brand new, they come from Amicci dello Scrambler (Italy), and they ran only 1500 km at a very low speed. It is the reason why I was surprised to feel with my hand some air blowing from the breather pipe. But as it is named, a breather pipe is made for that, and, if I understood well, as long as there is no oil projection, it is normal. It would be hightly unlikely that a new set of piston+rings is defective so early, isn-t it ?

[Dave354]

Hi, I agree. Very unlikely to be an issue with the rings given they are new. It sounds normal to me, the breather will always vent crankcase pressure to the air. I think the relatively narrow diameter of the hose from the vent will make that vented pressure feel more than it is.
Just enjoy! Oh and photos please!

Regards

Dave

[Rocla]

Here are some pictures from my website (you know my Scrambler, I have been posting some comments or questions at Motoscrubs for years):

The details of restoration:
https://strv.pagesperso-orange.fr/strvm ... Ducati.htm

Recent pictures of the beast:
https://strv.pagesperso-orange.fr/strvm ... alerie.htm