oil on underside of float bowls

[79beem]

I have noticed an increase in oil useage recently, but with compression good + no smoke I was a bit stumped. I spoke to the local bm guru who said 1 litre/1000km is acceptable. I'm not sure where I fit in with those figures but consumption has definately increased. Then today I notice oil forming into droplets on the underside of the floats bowls. A penny for your thoughts chaps ?

[Bob_Roller]

The crankcase breather exhausts into the rubber 'airhorns' inside the air box .

Not too uncommon to get oil dripping out of the tubes between the carb and cylinder head, it usually ends up dripping off of the carbs, the left one seems to be the favorite .

That is a bit high for oil consumption .

You may want to check the crankcase breather valve to see if it is still working as it should, it's under the top cover of the engine, next to the starter .

[montmil]

1st thought:  Are you turning off the fuel petcock each time you park the bike? Your drips could be a little bit of fuel overflow mixed with some oily on the bottom of the float bowl.

2nd thought:  Perhaps a "filled to the max line" engine oil sump. Try leaving the sump about a half litre low.

3rd thought:  Remove the air filter and check for pooled oil in the bottom of the plenum.

[tvrla]

A liter/1,000KM is a bit much in my book as well. A liter every 1500 is about the lowest I'd want to go. One of mine is at about that stage and I'm ready to open her up for a look at the rings and valves.

[Barry]

I wouldn't agree with your local guru that 1 litre/1000km is acceptable. If filled to half way up the dipstick that's half the oil capacity in just over 600 miles and it's getting on for 3 times the old 1 pint/1000 miles rule of thumb. A good engine should use a lot less than that. I'd peer down the plug holes with a narrow light source. You'd expect to see oil in the cylinder and on the piston top with a high level of consumption.

Oil consumption will be higher with sustained high revs and if it's original your 79 will have the old style disc breather that could be damaged. Might be worth a look at it.

[79beem]

Thanks for the responses chaps.
The 1l/1000km was apparently what BMW regarded as acceptable consumption for all R's. But it was suggested by the mech that perhaps BMW's figures may have been at the extreme end of consumption.
I'll throw that little hot potato into the circle and carry on.

Bob, how do I check if the breather is working properly?
It does occasionally ''Gobble-burble-gobble'' at idle. Oil is leaking between carb and air intake hose/tube not carb and head.

Monte, its definitely not fuel.Petcock working and is always turned off when parked up, even for short stops. I did fill her almost full recently but the leaking started before that.

Wirespokes ,
have you stripped down the heads before? I'd be interested to hear any tips for a full head strip down/recon. My pushrod seals leak, as do the head gaskets. I was quoted $2000+ for both sides, new gaskets ,seals, valves/seats,rings etc. It was determined by the mech that whilst these leaks made a mess they weren't responsible for the oil consumption increase.
I'm considering stripping her down myself and having the mech do all the recon and put her back together myself trying to save $.  

Barry,
I assume your suggestion re the breather is as per Bobs tip, what am I looking for?

Thanks again guys.    

[Barry]

To inspect the engine breather you need to remove the starter cover. The breather valve then sits inside a little round cover of it's own at the rear right hand side. The only thing you can check is that the paxolin disc is not damaged and the spring retainer is set on the top groove of the centre post. The later reed type breather is a direct replacement and is considered a more efficient design.

First things first ensure the breather disc is intact. Then if it is just to complicate things, the turkey gobble noise and possibly the excessive oil consumption is not necessarily the fault of the breather itself but can be the result of excessive piston blowby that produces more crankcase compression than the breather can cope with or it can be a faulty crankshaft seal letting air in which again also gives the breather more work to do than it can manage. On the other hand the fact that oil consumption increased suddenly sounds like it might just be the breather which would be by far the kindest outcome you could hope for. A new breather is a relatively cheap fix.

[Bob_Roller]

Here's a picture of the valve assembly, it's item # 12 .


http://www.realoem.com/bmw/showparts.do?model=0363&mospid=51897&btnr=11_1705&hg=11&fg=11

[tvrla]

Any idea what the consumption was before the recent jump?

Oak (a popular Guru here in the States) considers the earlier style breather superior. Had I known that I would have followed his instructions twenty years ago when I upgraded the one in my R90. It's actually simpler and cheaper than replacing, since all you need is a piece of electronic circuit board from which to cut a new disc.

Checking the heads is a special job requiring a spring compressor to remove the valves. Once the spring retainers have been removed and the springs are off, the grooves where the retainers lived must then be ground back to the original height, otherwise the valves won't pass through the guides. But without the springs on them you could wiggle them in the guides to get a feel for how much play they have. It's normally the exhausts that wear the most since they get the most heat.

How experienced at wrenching are you? It's difficult giving advice not having that data.

The oil you're seeing on the float bowls is coming from the breather which exits into the intake tubes. It will then drip out at the carb junction, but placing the screw part of the clamp on the top side will eliminate the dripping.

Even though the bike is running well currently, at that rate of consumption it won't take long for carbon build up to be a big problem - most likely sticking the rings and making things much worse. Best handle it now, since it is possible it's just the breather.

[bruce_launceston]

I concur with wirespokes hint; I also turned my hose clamps 180 degrees so that the screws are at the top and this stopped the oil stained boot syndrome.

[steven m]

I had an oil film under the carbs and on the top of my boots.  Just enough to be irritating but no obvious source.  I thought it was the pushrod tubes.  Then, one day, a puddle after riding.  Replaced the oil temp sensor and now everything is dry.  Of course that is left side only.

I agree with everyone else that a quart every 600 miles is a lot for these bikes.  If there is no smoke from the exhaust, where is the oil going?  

[badbmwbrad]

Oak has written about a small oil drain orifice located at the crankcase atmospheric vent.  The orifice provides a return path to the crankcase for any coalesced oil mist.  I'm not certain it's present on the R65, however, if the orifice is blocked then coalesced oil mist accumulates in the intake pipes.

Oak (a popular Guru here in the States) considers the earlier style breather superior. Had I known that I would have followed his instructions twenty years ago when I upgraded the one in my R90. It's actually simpler and cheaper than replacing, since all you need is a piece of electronic circuit board from which to cut a new disc.  

[Barry]

Oak has written about a small oil drain orifice located at the crankcase atmospheric vent.The orifice provides a return path to the crankcase for any coalesced oil mist. I'm not certain it's present on the R65,

I seem to remember looking for this drain and not finding it on mine. Maybe 81- on models have it.

[montmil]

Replaced the oil temp sensor and now everything is dry.  Of course that is left side only. 

Did you mean to say, oil pressure sensor?

[steven m]

Oops, oil pressure sensor, of course.