oil catch can

[JamesW]

Wish it was possible to install an automotive type oil catch can kit on a BMW oilhead.  Would be great if one could stop engine oil from getting into the air intake box as a result of crankcase ventilation.  Never heard of anybody doing this kind of mod to a motorcycle.

[Lowndes]

OK, go ahead and invent it.

[szurszewski]

The PO of my now sold K1200LT had capped the inputs on the throttle bodies and run the crankvent out the back of the bike. Not a problem unless you overfilled on oil, which apparently happened right before I bought the bike - spewed oil all over the FD, rear wheel, and all up the backside of the bike. 
 

I added a Fiji water bottle to the end of the hose until I had a chance to return it to the stock configuration. Caught a bit of oil in the bottle but not much. 
 

So...that’s all to say I don’t think it would be too hard to implement a functional system on an oilhead. 

[dave_a]

Most racing bikes have catch cans last I looked (admittedly along time ago). I don't understand why this is a problem unless you have excessive blow by, or are riding at sustained high rpm or overfilled. (google puke tank)

Have you taken a compression test or done a leak down test? 

I get nothing in my airbox. 150 psi compression.

 

[JamesW]

1 hour ago, dave_a said:

Most racing bikes have catch cans last I looked (admittedly along time ago). I don't understand why this is a problem unless you have excessive blow by, or are riding at sustained high rpm or overfilled. (google puke tank)

Have you taken a compression test or done a leak down test? 

I get nothing in my airbox. 150 psi compression.

 

No need as all is well with the bike just the normal coking up of the throttle body which I wish could be eliminated.

 

 

 

Quote

 

[Michaelr11]

James, the airbox functions as a catch for the oil. The oil collects in the bottom of the air box below the filter and it stays there until the drain plug is opened. If you’re getting a lot of oil in there, try keeping your oil level at the middle of the sight glass instead of the top.

[The Fabricator]

My 2000 r1150gs does not have any oil in the air box.  I run the oil level low as it consumes oil if I keep the level in the window.  I check it on the side stand.  As the unit holds almost a gallon and the side stand reading results in  maybe a quart low [if that much], I am not concerned about 'oil starvation' or what should I be concerned about?

I was wondering what 'coking up of the throttle body' means.  If you are referring to 'dirt' on the throttle plate, that would be the responsibility of the air filter.  I have never not seen dirt on the throttle plate.  Some dirt will always pass through the air filter.  The stock OEM filter is best.  It may not flow the most air and that is because it catches the most dirt.  No free lunch.

Also, routing the CCV to a bottle defeats the emissions reduction of the no-power-cost emission reduction system.

Same with the charcoal cannister.

[dirtrider]

13 hours ago, JamesW said:

Wish it was possible to install an automotive type oil catch can kit on a BMW oilhead.  Would be great if one could stop engine oil from getting into the air intake box as a result of crankcase ventilation.  Never heard of anybody doing this kind of mod to a motorcycle.

 

Morning James

 

Does your early (pre 1994)  1100RS still have that strange cone shaped "Oil Separator" on it? That was one strange oil venting device. But it sort of worked. Not as good as the later internal oil separation but it did work. 

 

If your early 1100RS motorcycle came with that Oil Separator & someone removed that at one time, or a return hose is plugged, or a return hose is pinched, they will puke oil like crazy. 

 

You could make up an additional  catch can of some sorts but you would still need to vent that catch can with a sizable vent to atmosphere as the 360° BMW boxer engine pushes a LOT of internal crankcase vent air due to the boxer type piston operation. Obviously you would still need to vent an additional catch can in a way that it can't puke oil onto the rear tire while riding. Even then you would have a difficult time mounting a large enough catch can with more internal volume & better baffling than your stock air box lower chamber. 

 

Might be better off just removing your stock air box's lower catch chamber's manual drain valve  & installing a hose fitting there. Then running a hose to a remote drain valve that you can more easily drain after every few rides. 

 

[dirtrider]

18 hours ago, The Fabricator said:

I was wondering what 'coking up of the throttle body' means.  

 

Morning Fabricator

 

Coking of the throttle bodies (usually occurs on the throttle body internal bore & on the throttle plates) is mostly due to unburnt fuel flashing off leaving a black carbon like coating from the fuel vapors that are left in the very hot combustion chamber & on the cylinder head side of the throttle plate after engine shutdown.  A slightly dripping fuel injector after shutdown significantly contributes to the throttle body coking.

 

Top tier gasoline's have blended additives to reduce the coking but even that can coke over time & numerous hot engine shut-downs.

 

Coking (unless really bad) doesn't really effect much at road-load  throttle openings but can significantly effect engine idle smoothness & can lower the curb idle RPM as it does restrict idle air flow through the mostly closed throttle plates & can restrict air flow through the  idle-air-bypass passages (BBS).   

 

Some coking can also come from any oil remaining in the hot cylinder (above the piston) or any oil residue remining on the engine side of the closed throttle plate flashing off after hot engine shut down,  but the majority of throttle body (and BBS passage) coking comes from any unburnt fuel flashing off on the engine side of the throttle plates after hot engine shut-down. 

[JamesW]

Thanks for that D.R. I'm going to have a closer look at the air box and crank case vent line and see what I see.  I know that nobody, but me, has ever done any service or mods to the bike.  I think the original owner installed a European headlight switch kit and the selling dealer did some recall work like replace the original telelever bearing.  I found the bike in 2012 and it had never once been even started since the day it was ran on the dyno after final assembly before being shipped from Berlin.  It was literally brand new in 2012.  The old guy that owned it had a collection of oilhead and early K bikes that were in the same condition as part of a BMW motorcycle collection.  Finally because of his advanced years he put everything on consignment at Brown Motor Works in SoCal and I spotted it on the internet and had it shipped.  

 

You know D.R. that picture you posted looks a lot like an oil catch can.  I'm going to see if I can find a part # for it.  I can't imagine where it would actually be mounted.  

[dirtrider]

13 hours ago, JamesW said:

 

ou know D.R. that picture you posted looks a lot like an oil catch can.  I'm going to see if I can find a part # for it.  I can't imagine where it would actually be mounted.  

 

 

Morning James

 

11151341346  Oil Separator  (used up to 05/94) on the 1100 RS. (RS is indeed a strange outlier).

 

If your engine has one/ had one/ or needs one is dependent on the engine having the lower drain back hose or fitting on the rear of engine (just under transmission on back of engine block)-- see picture  

 

 

[JamesW]

Hi D.R.,  You are right!  My bike (built 06/93) does have an oil catch can as your picture shows.  In the factory Service Manual it is call an oil strainer.  Maybe this oil strainer proved not to be too effective and hence was just eliminated.  I can't help but wonder how effective the crankcase ventilation system really is.  I mean crankcase pressures have always been an issue with these flat twins with those two gigantic pistons moving back and forth in unison.  Must have had a reason for installation of this oil strainer and then several months later just removing it.  Looks like I could just replace the strainer with a new version oil separator and just run the caught oil out under the engine.  Not nice for the environment but in the grand scheme of things........  Kind of looks like BMW engineering maybe recognized that it might not be such a good thing to just dump to much oil into the air box chamber but the oil strainer they employed just wasn't up to the job?  Probably just another mystery surrounding the elves of Wolfsburg in this case Berlin.

 

I have been tempted to just vent the crankcase directly to the open air but I've always wondered if this might result in contamination (dirt) being pulled into the crankcase as the pistons move outward?

[dirtrider]

31 minutes ago, JamesW said:

Hi D.R.,  You are right!  My bike (built 06/93) does have an oil catch can as your picture shows.  In the factory Service Manual it is call an oil strainer.  Maybe this oil strainer proved not to be too effective and hence was just eliminated.  I can't help but wonder how effective the crankcase ventilation system really is.  I mean crankcase pressures have always been an issue with these flat twins with those two gigantic pistons moving back and forth in unison.  Must have had a reason for installation of this oil strainer and then several months later just removing it.  Looks like I could just replace the strainer with a new version oil separator and just run the caught oil out under the engine.  Not nice for the environment but in the grand scheme of things........  Kind of looks like BMW engineering maybe recognized that it might not be such a good thing to just dump to much oil into the air box chamber but the oil strainer they employed just wasn't up to the job?  Probably just another mystery surrounding the elves of Wolfsburg in this case Berlin.

 

I have been tempted to just vent the crankcase directly to the open air but I've always wondered if this might result in contamination (dirt) being pulled into the crankcase as the pistons move outward?

 

Afternoon James

 

The old early 1100RS seems to be an outlier, the 1100RT, R, GS don't use (or need) that oil separator system. 

 

I have worked on so very few of those early 1100RS bikes so I am unsure of the engine internal differences. The later 1100 RS & RT, R, GS use a timed venting system through a timed vent in the crankshaft so they basically only vent at nominal crankcase pressure & shut the venting off at peak crankshaft pressures (peak piston displacements). 

 

Whether or not the early 1100RS use that same timed crankshaft venting & venting hole diameters is unknown to me (it would take a disassembled RS engine OR a LOT of research  to  determine if the early 1100RS contains the same internal crankcase venting & oil separation as the  later engines do.

 

I do know that if that oil separator isn't working correctly the early 1100RS bikes will vent a lot of oil.

 

The good part of your present oil separator is that it returns the trapped oil caught in the crankcase venting process back to the engine lower crankcase (well most of it anyhow).

 

You might be able to just leave the oil separator in place (that thing seems to work as designed)  but vent the outlet  hose that now goes to the air box out to atmosphere  (remove from going to the air box). That would solve your oil-in-the-air box problem.

 

Problem is, where to vent it to,  under the bike might put oil on the rear tire & out the back high would probably allow the oil mist to get sucked up in the swirling slip stream & possibly coat the rear of motorcycle with a light oil mist over time. 

 

Just running the engine vent out to under the motorcycle will probably give you a Harley like spot of oil on the ground  under the motorcycle every time you park it for a few minutes as the oil remaining in the venting hoses will condense then drip out as a fluid spot or puddle. 

 

 

  

[dirtrider]

Afternoon James

 

More____

 

I just checked my parts book & it looks like the crankshaft was the same up to well past the 5/94 date so that stayed the same pre & post external oil separator elimination.   

 

The engine case (block) was changed after the external oil separator elimination of 5/94 . That might mean that the internal crankcase venting/oil separation passages, timing notch areas are different pre & post external oil separator elimination. (OR) might just be due to the elimination of the not-needed oil drain back fitting pressed into the rear of the engine case. (I just don't know on this without having an early & late engine case side by side for detailed internal venting comparison) 

 

The internal oil separation is kind of a multiple belt/suspenders thing as 'most' of the initial oil separation from the  vented crankcase  air is due to the crankcase initially venting into the spinning crankshaft counter weight (the spinning & centrifugal forces tend to throw the heavier oil back out of the crankshaft vent hole so mostly just vented air/combustion blow-by  goes through with some oil mist carried with  it, then it goes out the side on the  rear of the crankshaft through that timed notch with the heavier oil that condenses running out the bottom back into the crankcase  & the lighter air & slight oil mist remaining going up through a labyrinth type cavity with any addition oil mist that condenses in the labyrinth  trickling back into the lower passage then back into the crankcase.

 

What's left (crankcase vent air/oil mist) then goes out through the top engine vent fitting where it enters that external oil separator, from there the separator does it's thing swirling the air/oil mist with the heavier oil mist condensing inside the oil separator then falling to the bottom of the oil separator  where it returns to the  lower engine crankcase through that exit hose on the bottom of the oil separator funnel.

 

Then, what little oil mist that is left (not very darn much at this point) goes from the top of the oil separator to the lower chamber on the air filter housing. Anything heavy drops to the bottom of the air filter lower chamber & anything in the vent air remaining gets sucked in with the intake air then  burned in the engine.

 

Due to the boxer design with fairly large crankcase displacement changes the venting hoses are fairly large diameter so terminating the final vent outlet inside the air box allows open hose unrestricted crankcase venting with a somewhat protected termination point to keep bugs & mice out of the venting track. 

 

Again, due to the boxer engine having a large internal volume change at each 360° crankshaft rotation the crankcase needs to vent very  freely to prevent excess pressure causing oil leaks at the seals or blowing the sight glass out but still use multiple points of oil separation from the vented air.

 

 

[JamesW]

Thanks for the info D.R. I really appreciate it.  I think I'm going to leave well enough alone.  One thing that does bother me is could this early oil separator/strainer malfunction and what would one do if this occurred?  I think there is room to replace the strainer with a new automotive oil can separator but now I don't think I want to go there.  This is kind of progressed beyond my pay grade.  My original thought was to just incorporate an  oil separator but that was before, thanks to you, I learned that my RS already has an oil separator.  I just assumed it didn't, wrong!  

 

Blown out oil sight glasses were an issue with these bikes.  I safety wired my sight glass in place to hopefully prevent this from occurring several years ago. 

[dirtrider]

14 hours ago, JamesW said:

Thanks for the info D.R. I really appreciate it.  I think I'm going to leave well enough alone.  One thing that does bother me is could this early oil separator/strainer malfunction and what would one do if this occurred?  I think there is room to replace the strainer with a new automotive oil can separator but now I don't think I want to go there.  This is kind of progressed beyond my pay grade.  My original thought was to just incorporate an  oil separator but that was before, thanks to you, I learned that my RS already has an oil separator.  I just assumed it didn't, wrong!  

 

Blown out oil sight glasses were an issue with these bikes.  I safety wired my sight glass in place to hopefully prevent this from occurring several years ago. 

 

Morning James

 

Problem with a lot of auto type oil separators is that they are not set up to re-introduce the separated oil back into the crankcase. Even on the ones that are  they were probably not designed to deal with the extreme crankcase pressure variations of the BMW boxer engine.

 

I haven't ever cut the BMW 1100RS oil separator apart but my guess is that strange looking long funnel type construction is designed to work as a sort-of hydraulic check valve as the bottom of the 1100RS oil separator dumps the separated oil directly back into the crankcase.

[JamesW]

Bob's BMW parts list for my bike shows that the OEM oil separator is still available for $52.  That's one thing I've always liked about BMW the way they support decades old motorcycles with new parts.  

 

Nope, I don't think it would be a good idea at all to replace the OEM separator with anything but an OEM part for sure.

 

Thanks again for your insight.