BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: M Brook on 04 December, 2017, 13:52:48

Title: Oil coming from breather on my A10 1961
Post by: M Brook on 04 December, 2017, 13:52:48
Hi

When I first start my A10 from cold oil leaks from the breather in the engine case behind the primary drive. Once the engine has run a while the oil stops, and I can stop and start the engine and it doesn't leak oil again, until I start it from cold. Any ideas?

Thank you,

Mark   
Title: Re: Oil coming from breather on my A10 1961
Post by: JulianS on 04 December, 2017, 14:23:43
Probably wet sumps when parked up log enough to get cold, and on starting up pumps the excess oil out of breather.

Drain the sump when its cold and check how oil comes out. My A10 does not wet sump and when checked this way I usually get about 100ml out. If you get much more than this bike is wet sumping.
Title: Re: Oil coming from breather on my A10 1961
Post by: M Brook on 04 December, 2017, 14:32:13
Hi
What do you mean by wet sumping?

Cheers
Mark
Title: Re: Oil coming from breather on my A10 1961
Post by: M Brook on 04 December, 2017, 14:44:47
Or and what is the cause of wet sump
Title: Re: Oil coming from breather on my A10 1961
Post by: M Brook on 04 December, 2017, 15:34:07
Or and what is the cause of wet sump
Title: Re: Oil coming from breather on my A10 1961
Post by: DEREKANDERSON8 on 04 December, 2017, 16:27:11
oil is draining from the oil tank into the crankcases via the oil pump, common complaint on british bikes!

google wet sumping

 >:(
Title: Re: Oil coming from breather on my A10 1961
Post by: JulianS on 04 December, 2017, 17:01:54
Wet sumping usually caused by the anti syphon valve in sump being obstructed or a worn pump, pump not seating properly on crankcase or the hard to get at non return valve not seating properly. Or a combination of any.
Title: Re: Oil coming from breather on my A10 1961
Post by: M Brook on 04 December, 2017, 17:08:47
Hi
Thank you for your answers, sounds like the oil is running back into sump because it only happens after not starting the bike for a week or more. Is there anything I can do about it or just life with it.

Mark
Title: Re: Oil coming from breather on my A10 1961
Post by: A10 JWO on 04 December, 2017, 17:34:32
Can of worms this one, you will get many answers on this one and there have been many threads on this over the years.
Title: Re: Oil coming from breather on my A10 1961
Post by: M Brook on 04 December, 2017, 18:33:20
Thanks again for advice, I think I will live with it until I have other work to do on the bottom end of the engine. I want install auto advance gear and electronic ignition. I have a couple of questions to ask. I will start new post.

Mark 
Title: Re: Oil coming from breather on my A10 1961
Post by: Mike Farmer on 05 December, 2017, 09:42:08
 :)
Having had the same problem I put an anti wet sumping valve in the inlet pipe to the engine. Does the trick. cost about 35. Lots of people use this system.

Mike 8) 8)
Title: Re: Oil coming from breather on my A10 1961
Post by: M Brook on 05 December, 2017, 13:05:39
hi Mike
Thank you for your comment, where did you get the anti wet sump valve from and where exactly did you fit it.

Cheers

Mark

Title: Re: Oil coming from breather on my A10 1961
Post by: Mike Farmer on 05 December, 2017, 14:02:16
Hi.  :)

Purchased from ebay. Fitted in the pipe line going from the oil tank to the engine. Mine is on my current A50 but I assume they are reasonably the same. I haven't had an A10/A7 for a long time.

So my memory may be in need of slight adjustment.

Mike 8) 8)
Title: Re: Oil coming from breather on my A10 1961
Post by: Mike Farmer on 05 December, 2017, 16:32:25
Hi Agen.

Just in case you haven't found it.
.
Its ebay item No401447465843.

Don't know if anyone else has thoughts on this.
Mike 8)
Title: Re: Oil coming from breather on my A10 1961
Post by: A10 JWO on 07 December, 2017, 16:18:47
Mike they can fail as we all know and engine goes bang, in line taps also forgotten to turn on BIG BANG.
Title: Re: Oil coming from breather on my A10 1961
Post by: RoadRocket on 07 December, 2017, 17:36:37
Wet sumping usually caused by the anti syphon valve in sump being obstructed or a worn pump, pump not seating properly on crankcase or the hard to get at non return valve not seating properly. Or a combination of any.
Could also bypassing the gears in the pump if there is too much clearance?