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Old 05-13-2012, 06:36 PM   #1
2GbeemerLUV OP
Bavarian Motor Pie
 
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Joined: Mar 2012
Location: philadelphia, pa
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Question venting oil

still trying to diagnose a rich, wet, plug fowling right cylinder. whilst checking the air filter (which was wet looking and black as well) i noticed the crankcase ventilation system was leaking oil into the air mix.

is this the function of the ventilation system? the very little i know about it, leads me to believe there should only be "blowby gasses" (clymers) and not oil. it seems oil in the air, thus in the carbs, thus in the heads is whats causing all of my current problems--- but have i just uncovered another????

please, how bad is this, and what needs to be done?
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Old 05-13-2012, 07:04 PM   #2
Hawk Medicine
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Before you do anything else, you'll want to check your crankcase breather vent for proper operation.

Chances are about 90% that thats where the problem lies.
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Old 05-13-2012, 08:18 PM   #3
Biebs
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Valve guides top end

I had a similar problem 89 r100 gs. Had oil blowing out breather bike leaking oil from air cleaner area.

Removed right side valve started engine had a puff of compressed air on each cylinder compression stroke.

My mechanic looked at bike said I had worn valve guides excessively worn.

When pulled apart the piston were black with burned oil - rings were bad.

Total rebuild done on cylinders. New rings,connecting rod bearings,new valves,valve guides, all done.

Runs great now cost mucho dinero. 50k miles on bike at this time.

But give some more info on year of your bike and current miles.

Airheads do have some known problems for certain years.


Looked at your profile saw was a r60/6 1975. What is the mileage ??

Biebs screwed with this post 05-13-2012 at 08:49 PM
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Old 05-14-2012, 08:34 AM   #4
DoktorT
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The /6 breather is a fiber washer held by light spring pressure. You can polish the washer for better seal. You can addjust the spring for more pressure. You can get or make a thicker washer, or glue a thin disc of rubber on the bottom of the washer. Or you can replace the /6 breather with the later type leaf type breather. None of this will resolve an issue of excess blow by.

I think I would want to do a leak down test on the cylinders just to verify compression losses that may be the seat of the issue.

Worn valve guides can be confirmed by turning the crank until the valve opens but a few milimeters, then pushing the top of the valve forward and back to see how much play you got. A coupla milimeters at the top of the valve is OK. More than that and best budget for valve guides replacement.

The exh valve guides tend to wear out much faster than the intakes. Just much higher heat means more wear.
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Old 05-14-2012, 08:55 AM   #5
Airhead Wrangler
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This can also result from overfilling with oil. Don't fill it all the way to the full mark on the dipstick. Midway is better and you might find that oil consumption stops at the midway mark. Also check the drain hole in your breather tunnel on top of the block (if you have one. What year/model are we talking about here?). It's visible under your breather valve and can be cleared with a paperclip or other poking implement if clogged. If it gets plugged with something, the tunnel fills with oil which then gets blown out your breather. Why it's only happening to your right cylinder is a bit concerning though. Be that as it may, I'd eliminate the simple stuff first before you go looking for bigger problems.

EDIT: alright, now I see we're talking about an R60 here which doesn't have the oil mist condensing tunnel and drain hole mentioned above. Nevermind.
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Airhead Wrangler screwed with this post 05-14-2012 at 09:05 AM
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Old 05-14-2012, 09:01 AM   #6
2GbeemerLUV OP
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the odo says the bike has about 36k on it, but im not sure if this is accurate. i inherited this machine from my father who took great care of it, but may have done a rebuild or something that would affect the actual reading (he was always working on his bike).

"Or you can replace the /6 breather with the later type leaf type breather. None of this will resolve an issue of excess blow by." does this mean the excess in the ventilation unit itself is a symptom, not the cause?

also, last time i pulled my plugs and advanced the pistons, with a flashlight, i noticed both pistons were black- is this normal wear for a bike this old? or does this tell me i have a "mucho dinero" job in store like biebs?

darnit, i just wanted to ride this spring!!!!
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Old 05-14-2012, 09:31 AM   #7
Biebs
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Thumb Good advice

On the oil level do not fill to top mark my 74 R75/6 runs at oil level about middle of dip stick if I fill to top mark on dip stick it will burn off the extra oil and settle at the middle of stick and stay there forever like that spot.

So if you are fill crankcase to much you will burn off /have oil coming of breather. Black pistons show you are burning oil not a good thing.
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Old 05-14-2012, 11:54 AM   #8
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Running your oil level half way down the stick? I have seen a lot of airheads and oilheads run completely out of oil. Don't bank on the oil usage leveling off. I know a lot of people report just that but I have never seen it. All my bikes will go down to the half way mark and then go down from there even faster. I understand the logic behind increased crank volume due to lowered oil levels but . . . . I have seen a lot of beemers run completely out of oil. Keep an eye on it!

I just re-read the service bulletin on the subject. The last paragraph I believe on the subject makes no sense whatsoever just like many a BMW service bulletin. Less oil volume makes no difference at all? On planet earth?
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Old 05-14-2012, 01:24 PM   #9
2GbeemerLUV OP
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supershaft,
can you direct me to these bmw service bulletins?
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Old 05-14-2012, 01:55 PM   #10
Hawk Medicine
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I posted the original BMW bulletin a little while ago and it can be found here: http://www.advrider.com/forums/showthread.php?t=787850

I can't speak for SS but I've found that once my R75 and R90 engines reach the correct "ulleage space" (Spelling?) (About half way between full and fill.) they essentialy stop using oil between oil changes.

OTOH, when running at high speeds (85 to 90+ mph) over long distances (500 miles or more per day), the R100s seem to use a few ounces of oil anyway, despite the oil cooler. I chalk that up to "severe useage" and add oil every day or so and change oil more frequently. At more normal speeds, my R100 engines perform about the same as the smaller displacment ones.

The mail thing is to watch the oil useage in YOUR engine and attend to it's needs, because as always, YMMV.

PS: There may have been further bulletin from BMW over the years but the one I posted is the only one I've ever seen.
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