Oil loss???

[lrz]

It seems I'm losing a good bit of oil out the filler even with dipstick snug; can the gasket there be too old to seal allowing enough oil to coat the side of the motor in 15 miles?
It doesn't seem possible to me but it's occurred twice now. Oil is not coming from the starter area weep hole nor from PRT seals or timing hole . Clearly originates at the top of the filler "neck".
Anyone ever have that metal gasket/washer/seal ring for the dipstick fail w/similar results? I'm sure it's original '77 vintage.
I'm stumped...

[George Ryals]

Take your dip stick into a hardware store and buy an o-ring that fits tight enough to not fall off.

[Garnet]

And make sure your breather is not stuck closed.

[John Falconer]

If your rear main seal (or any other crankcase seal) is not doing its job then you'll have leakage as you describe, even if there's nothing mechanically wrong with the breather. What's the history of this motor?

[Duane Ausherman]

I bet that you have too much crankcase pressure. Those metal O rings didn't really seal at all, so I doubt that is the problem.

[lrz]

Thank you for your replies.
A brief history:
re-ringed about 3k mi ago, unsure if rings seated so bores were just, as in recently, lightly ball honed- don't know what grit shop used but cross hatching seemed fairly light vs smooth prior, re-used rings which measured in spec, oil changed (not filter) 20w50 after re-assembly and now the oil loss.

breather is the old style w/ a new disc maybe 2k mi ago as well as a brand new breather hose-which was a little tough to source.

So, I'd guess some correlation between the honing & the leak but what is it?

[John Falconer]

But what's the history of the motor, overall. When was the rear main seal last changed? Has the motor sat for an extended period? Have you inspected the seals at the front of the motor? If the new rings didn't seat that will contribute to crankcase pressure but I'm suspicious of the seals unless you have positive information to share related to them.

[lrz]

I've got this page up as I go about me paperwork, so-
Cam seal replaced w/in 1k mi due to weeping, oil pump o-ring replaced w/in 3kmi, rear main did not leak & looked like the newer type & was left in place there is no oil on the "shelf" under trans at all, bike has been run less than usual this summer & certainly not daily, but not in long term storage either; cylinders were honed 300 +/- mi ago.

[the quinner]

A couple of things: Be certain that the whole breather system is working...INCLUDING the hole that allows oil to return to the crankcase. (there's a small housing in FRONT of the housing that holds the breather valve...under the housing is a cavity...at the bottom of the cavity is a small hole...if the hole is clogged, consumption goes up.)

Next...replace the $0.50 aluminum crush washer on the dipstick. Don't use a rubber o-ring...use the correct aluminum CW (rubber o-ring is used on the 1981+ bikes...metal crush washer on the earlier bikes). AND...use the pliers in the toolkit to tighten and loosen the dipstick (as per BMW)...the metal dipstick washer can and does seal well if done according to Herr Hoyle.

Finally...look at the bulletin (below) about oil consumption and notice the section labelled "important." (summarizing:) Rings will not be fully seated and sealing until a minimum of 5000 miles. I think maybe you were a little over-zealous by going in and honing a second time. At minimum, you "un-sealed" the rings a bit...leading to extra blow-by during combustion...which will find the easiest way out (a less than sealed dipstick is a very easy way out).

I'd check the drain hole in the breather system...replace the crush washer...and ride the bike as if you are trying to break-in new rings. A little time...fifty cents...and avoid the highways.

[the quinner]

If anybody cares to see that whole bulletin...here is a link:

https://picasaweb.google.com/1095429319 ... directlink