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Air beathed out from the oil breather pipe (350 Scrambler 1974)
Posted: Mon Apr 17, 2023 1:45 pm
by 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?
Re: Air beathed out from the oil breather pipe (350 Scrambler 1974)
Posted: Mon Apr 17, 2023 2:09 pm
by 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
Re: Air beathed out from the oil breather pipe (350 Scrambler 1974)
Posted: Mon Apr 17, 2023 3:34 pm
by 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
Re: Air beathed out from the oil breather pipe (350 Scrambler 1974)
Posted: Mon Apr 17, 2023 4:12 pm
by 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
Re: Air beathed out from the oil breather pipe (350 Scrambler 1974)
Posted: Mon Apr 17, 2023 5:59 pm
by Duccout
Hi Claude,
I would not worry then, just keep an eye on it in case any oil starts to spray out.
Cheers,
Colin
Re: Air beathed out from the oil breather pipe (350 Scrambler 1974)
Posted: Mon Apr 17, 2023 7:15 pm
by Eldert
sound like a ring sealing problem
what brand piston did you fit ? a Wössner from Jesus Guzman ?
Eldert
Re: Air beathed out from the oil breather pipe (350 Scrambler 1974)
Posted: Tue Apr 18, 2023 9:44 am
by 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
Re: Air beathed out from the oil breather pipe (350 Scrambler 1974)
Posted: Wed Apr 19, 2023 8:50 am
by 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 ?
Re: Air beathed out from the oil breather pipe (350 Scrambler 1974)
Posted: Wed Apr 19, 2023 1:33 pm
by 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
Re: Air beathed out from the oil breather pipe (350 Scrambler 1974)
Posted: Wed Apr 19, 2023 3:12 pm
by 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.htmRecent pictures of the beast:
https://strv.pagesperso-orange.fr/strvm ... alerie.htm