Blocked breather in 1150 crankcase

[rob18362]

Anyone know what the design of the breather is in the 1150 crankcases? Mine is blocked. The rubber hose to the air box is clear but the crankcase end is solid if you either blow or suck through it (with the oil filler cap removed)! Is there a valve or filter in there or is just an open pipe. The crankcases are pressurizing every time I run the engine and I am worried about damage to oil seals etc.
Any ideas?
Can I do any harm if I try blowing through it with my airline?
Any help will be appreciated as we're off to Knordkapp next month so the bike has to be A1!
heers, Rob.

 

[Steptoe]

What makes you think it's blocked - you can't blow through it, it only works one way

 

[rob18362]

Blocked breather.

Hi Steptoe,
Good to have you on the case.
Yes thought it may have one way valve so tried sucking and still nothing. The reason I believe it is blocked is that when you switch the engine off and then remove the oil filler cap even after a short wait it is like taking the lid off a pop bottle as the pressure escapes. Also oil consumption has suddenly gone through the roof and I was previously using non (80,000 mile engine). Clouds of smoke on start up which I have never had before. If if I take the cap off when I stop and let the pressure out then there is no smoke on start up. It' s definately not right.
Any thoughts on freeing the breathing will be appreciated.
Cheers, Rob.

 

[Steptoe]

Leave the cap off

 

[rob18362]

The oil mist will do wonders for improving the waterproofing of my left boot if I leave the cap off but I think I'd sooner sort whatever the problem is. Am I the first to experience this, surely not.
Help, please some one this is a real problem.
Thanks, Rob.
P.S. Steptoe, if you know that the breather has a one way valve in it can you either describe the arrangement or suggest where I can get some info. Can,t surely be one of those "refer to your B*W dealer moments"! Tks

 

[JoeKnow]

The breather system runs through the two crank seals at the back of the crank.Some times the inner seal moves and gets pushed back against the outer seal,thus blocking the breather holes in the crank.The brether system is timed,thats why you cannot suck of blow through it.Usually when the seal moves it just fills the airbox up with oil(thats why it smokes) have you drained the airbox for oil.........

 

[rob18362]

Hi Joeknow,
Thanks for your input. Can you give me a fuller description of the system if possible. The exit of the breather to the airbox is via a pipe that exits the crankcases at the top/front/left near the telelever pivot can you tell me how it is routed through the rear crank seals. Accept what your saying just want to fully understand it.
Cheers, Rob.

 

[JoeKnow]

Hi Joeknow,
Thanks for your input. Can you give me a fuller description of the system if possible. The exit of the breather to the airbox is via a pipe that exits the crankcases at the top/front/left near the telelever pivot can you tell me how it is routed through the rear crank seals. Accept what your saying just want to fully understand it.
Cheers, Rob.

The breather at the back of the crank goes up the engine,through a labrynth system(to stop the bulk of the oil that made it in to the breather)and the up the top of the engine,through the hose to the airbox.
Have you drained the air box to see if it is full of oil??

 

[rob18362]

The breather at the back of the crank goes up the engine,through a labrynth system(to stop the bulk of the oil that made it in to the breather)and the up the top of the engine,through the hose to the airbox.
Have you drained the air box to see if it is full of oil??

Hi Joeknow,
Yes I drained the airbox and there was just 5ml of oil in there so nothing excessive.
However your information has now helped me realise what the problem is.
I rebuilt this bike over last winter replacing the gearbox. When I had the clutch out I thought it would be prudent to change the rear crank seals. If I understand what your saying about the breather then it looks like despite taking careful measurements I have got them slightly out of position and have caused a block in the breather system ! I never was able to understand why the oil window popped out soon after but was told it sometimes happens for no apparent reason. Well now I know better.
As I head to Knordkapp in 3 weeks I now have to decide whether to add an additional breather (probably via the fillercap and with an oil trap) or strip the whole thing again !! Hopefully getting it right this time of course.
Any thoughts or other options you can suggest would be welcome.
Thanks very much for your valued input.
Cheers, Rob.

 

[JoeKnow]

Hi Joeknow,
Yes I drained the airbox and there was just 5ml of oil in there so nothing excessive.
However your information has now helped me realise what the problem is.
I rebuilt this bike over last winter replacing the gearbox. When I had the clutch out I thought it would be prudent to change the rear crank seals. If I understand what your saying about the breather then it looks like despite taking careful measurements I have got them slightly out of position and have caused a block in the breather system ! I never was able to understand why the oil window popped out soon after but was told it sometimes happens for no apparent reason. Well now I know better.
As I head to Knordkapp in 3 weeks I now have to decide whether to add an additional breather (probably via the fillercap and with an oil trap) or strip the whole thing again !! Hopefully getting it right this time of course.
Any thoughts or other options you can suggest would be welcome.
Thanks very much for your valued input.
Cheers, Rob.

Yeh the seals are abit of a fiddle,the inner one is slightly smaller than the outer one.The trick is not to damage the seal lip as there is a groove in the crank that you have to push over.It's easy with the special tool as it has a guide for the seal to go over.
Just be 100% sure it the seal before you pull it all apart again
If you want any more help let me know

 

[ahebron]

.
As I head to Knordkapp in 3 weeks.......

That is somewhere I would love to go. Please do a write up and lots of photos.

 

[rob18362]

Calling Joeknow again!

Hi Joeknow sorry to keep pestering you but you know what your talking about and I've struggled to get any other sound info on this. Given what I told you about changing the seals can you understand how I can have caused a complete blockage of the breather. It is completely solid and the crankcases pressurize as soon as the engine is started. Can't think of anything other than I must not have located the seals correctly and can see no fix other than a complete strip down. If only there was!
Will leave you in peace after this.
Thanks again Rob.

 

[JoeKnow]

Hi Joeknow sorry to keep pestering you but you know what your talking about and I've struggled to get any other sound info on this. Given what I told you about changing the seals can you understand how I can have caused a complete blockage of the breather. It is completely solid and the crankcases pressurize as soon as the engine is started. Can't think of anything other than I must not have located the seals correctly and can see no fix other than a complete strip down. If only there was!
Will leave you in peace after this.
Thanks again Rob.

The breather is quite simple,the only thing that can go wrong is the seals can you get me the VIN #

 

[rob18362]

Thanks.

The breather is quite simple,the only thing that can go wrong is the seals can you get me the VIN #

I believe it is the seals being out of position (mine has 2 seals at the rear) from the rebuild.
Local independent BMW technician agrees and I am booking it in with next week for repair. Would have done it myself but with Knordkapp trip so close don't need the hassle, just need it right.
Thanks again for all the advise.
Cheers, Rob.