The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Einar on October 01, 2015, 03:47:18 PM
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Hi everyone,
I took off the air filter today, and discovered that the box below was full of oil (engine oil, i presume).
1. Where might this oil come from?
2. What is the function of the T-section tube? Ventilation system from the crankcase?
3. The engine oil level is exactly in the middle between min/max on the fuel gauge stick. Could it be that it's still too much?
When I removed the carburaters, I saw oil pools inside the cylinders as well, I was advised the ventilation system might dispose oil into the airtube. Is this what I also see in the airbox?
4. If so it would mean that the black tube behind the airbox is the vent-tube from the engine, yes? Am I then right to assume that the seal between the black tube "behind" the box and the T-section must be poor and that's how the oil gets in?
This oil leaks down on the outside of the engine (from under the airbox, appears to come out via the hole that bolts the box to the engine), and creates a mess on the external parts, preventing me from clearly evaluating the integrity of other seals such as driveshaft.
5. Do I need to change the oil filter? Milage unknown.
Any help would be greatly appreciated.
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It's pretty common to get oil in the airbaox and have it drip out of the carbs .
You may want to check the crankcase breather valve to make sure it's still working, or even installed, if you are not the original owner, previous onwers can do some weird things to their bikes . :D
On '81 model year bikes and later, it's just a metal reed valve, on the earlier bikes, it's a spring loaded valve .
A usual cure, is to not fill the oil to the full mark, some bikes just atomize the excess down to a point, then the level stabilizes .
What weight oil are you using ???
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Thank you for your reply Bob_Roller.
Great tip. I will look for the crankcase breather valve. I was not even aware of its existence. :) Where is the valve situated?
I am not the original owner, it's an R65, 1981.
I just bought the bike recently, I've been told by the previous owner the oil is Castrol 10w-40 synthetic. I am planning to change it.
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Remove the top cover just forward of the air box and you'll spot the breather valve. There is also a small drain hole nearby that provides a return to the sump. It must be open. Probe with a pipe cleaner.
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Normal. Lived with it for years. There is a rubber reed valve on the back of the air box - some may drain out there. Wouldn't worry about it too much. Helps lubricate the top end.
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When you say "top cover" you mean the engine cover under the gas tank that is bolted to the block? That sounds like quite a job, I will try to get on it this weekend.
At least it is good to know it is nothing pressing and I can drive it without causing any serious damage.
Thanks guys and have a good weekend.
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When you say "top cover" you mean the engine cover under the gas tank that is bolted to the block? That sounds like quite a job, I will try to get on it this weekend.
You can see the cover in your photos. Sits just forward of the upper part of the air cleaner box. If memory serves, there are but two Allen-head screws that hold the cover in place.
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Update on the air box story:
Over the weekend I opened up and got to the breather valve.
It seemed like the reed valve was installed and functioning (I can bend it, I assume that means it's working), however;
1. The tube from the breather valve and connection to the t-section seemed to have come loose - possible leak source
2. The gasket under the breather valve housing was probably from 1981 (along with most of the important seals on this bike) - possible leak source
Questions:
a. Does anyone have the part number for the gasket under the breather valve?
b. Part of a clamped down housing just in front of the air box is cracked and partially damaged. What is this piece and is it a concern that it's damaged?
c. Can anyone point out the drain valve from the photos attached?
d. Any other possible leak sources that you can see from the pictures?
Will open up again in a week's time after having driven around a bit to see if the oil has disappeared + install breather valve gasket.
Thank you all for your help!
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This should show you all the parts you need .
http://www.realoem.com/bmw/enUS/showparts?id=0364-USA-09-1980-248-BMW-R65&diagId=11_1712
Just an added note, I saw a ' modification ' to the crankcase breather about 22 years ago, a simple job, cut a piece of a copper pot scrub pad and place it in the housing of the breather valve, not enough to clog the airflow, but just enough to let the atomized oil collect on the pad and then get returned to the sump .
Seems to work, I get very little oil in the airbox, or oil dripping out of the carbs since I have done this .
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Excellent! Thanks for the link and modification advise.
Your input is invaluable. :)
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As to your 'drain hole' question, look just forward of the crankcase vent flapper. There is an area referred to by BMW as a settling chamber. At the bottom is a small drain that returns oil to the sump... unless it's clogged up. Pipe cleaner, small wire, whatever but confirm to opening is clear. The drain is on Airheads mfg'd from 1978 onward.
The photo is from an engine cutaway lifted from The Snowbum's website. Thank you, Robert Fleischer.
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fi196.photobucket.com%2Falbums%2Faa1%2Fmontmil%2FBMW%2520Engine%2F1978gtsettling%2520chamber_zpslzskeuyf.jpg&hash=635895d4aea72e69ca7ba5d8bd3cbe4fca0fbd3e) (http://s196.photobucket.com/user/montmil/media/BMW%20Engine/1978gtsettling%20chamber_zpslzskeuyf.jpg.html)
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Thank you Monte, great input! Yeah that hole looks like it could clog up easily.
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As to your 'drain hole' question, look just forward of the crankcase vent flapper. There is an area referred to by BMW as a settling chamber. At the bottom is a small drain that returns oil to the sump... unless it's clogged up. Pipe cleaner, small wire, whatever but confirm to opening is clear. The drain is on Airheads mfg'd from 1978 onward.
The photo is from an engine cutaway lifted from The Snowbum's website. Thank you, Robert Fleischer.
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fi196.photobucket.com%2Falbums%2Faa1%2Fmontmil%2FBMW%2520Engine%2F1978gtsettling%2520chamber_zpslzskeuyf.jpg&hash=635895d4aea72e69ca7ba5d8bd3cbe4fca0fbd3e) (http://s196.photobucket.com/user/montmil/media/BMW%20Engine/1978gtsettling%20chamber_zpslzskeuyf.jpg.html)
Anyone actually seen this hole on an R65 as opposed to other airheads ?
Don't know about the later models but my 79 doesn't have it.
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The tips the guys gave you are all good - another thing to also consider since I couldn't see it in your pictures - are the hoses/tubes that are supposed to go out of the airbox from the T-connector down to the vacuum ports on the carbs in good shape and not blocked up? These may need periodic replacement due to age/cracking or getting plugged up with a combination of oil and road dust.
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Good point! I will verify that there are no obstructions on the hoses from the t-connection.
1 Question:
Could a bad air filter cause this?
I ordered air filter + Gasket for the breather valve, once it has arrived I will open the bike up again to change parts,change engine oil (10W-40) and verify integrity.
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Could a bad air filter cause this?
Not very likely. The air filter lasts a long time before it causes problems.
Did you find the oil drain hole ? I wasn't 100% certain before and perhaps still not but having done some research and looking at your pictures again I'm thinking that type 248 engines (that's both early and later R45/65's) don't have the same drain hole that other post 78 type 247 airheads have. There is almost no information anywhere to confirm this even on Snowbums site but it can be deduced from the style of the breather cover and that fact that it exits vertically and turns down before being teed off to each carb intake.
Why they didn't apply this drain hole mod to the type 248 block I don't know. Perhaps they thought crankcase breathing was less of a problem on the smaller capacity engines and also thought the vertical rise would help compared to the early breather covers which had a horizontal outlet. Anyway don't be concerned if you don't find the drain hole.
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Thank you for the response Barry. Great input!
I did not find the oil drain hole when I took the engine cover off. I will repeat the exercise this weekend and have another look according to the uploaded cross-cut photo.
I'm unfamiliar with the differences 247 vs. 248 but from your comment I assume mine is a 248? Model year 1981.
It does appear the cross-cut is slightly different than the on my bike. Ref. your 247 vs 248 comment.
What puzzles me with this drain hole is:
Does it make sense to put a 'return-to-sump'-drain outside the breather valve. Wouldn't that be designing with a leak in mind?
Will check again this weekend once I'm back home from travels and update the post when I have some new information.
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I'm unfamiliar with the differences 247 vs. 248 but from your comment I assume mine is a 248? Model year 1981.
It does appear the cross-cut is slightly different than the on my bike. Ref. your 247 vs 248 comment.
What puzzles me with this drain hole is:
Does it make sense to put a 'return-to-sump'-drain outside the breather valve. Wouldn't that be designing with a leak in mind?
Yes yours is a type 248. That's just shorthand for the short stroke R45/R65 engines. Although there are many common features, the longer stroke type 247 engines in R80's R100's etc use a different block. Type 247's have for example different angled pushrod tubes and in the case of post 78 engines the said oil drain hole which I'm suggesting the type 248 blocks don't in fact have.
On the engines that do have the drain hole, Although I see what you mean about a designed in leak bypassing the breather, I think it still makes sense to put it outside of the breather valve to give any condensed oil vapour a chance to return to the sump rather than pass through to the carbs. Providing it's able to cope with any piston blowby the breather is designed to keep the crankcase at a slight vacuum so the condensed oil would be pulled in through the drain hole.
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Thank you for the clear explanation, Barry.
Once I can verify the presence/absence of the drain hole I will update the thread. If it's there, I assume it must be located directly in front of the air box or in the sump in front of the breather valve.
Will keep you posted.
Cheers.
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Hi all,
Just to close out this topic with my final findings.
The problem was two-fold and rather simple:
1. The hose that goes from the oil-breather valve and into the airbox was poorly attached and leaked oil vapour.
2. The gasket on the breather valve had never been changed and was practically melted into the steel.
3. In addition, I maintain, as advised, an oil level slightly on the lower side of the dipstick interval.
After having addressed these two things, the oil leaks have now stopped completely so the airbox and top of engine block are now oil free.
Thank you all for your help on this. I learned a lot.
E/