Oil filler cap

[sstein]

Mine was weeping oil. Replaced it last summer and now new one weeping again! Would like to replace with oem aluminum cap. Wunderlich? Creative cycle concepts? Recommendations?

[timl]

My 2004 was leaking badly so I replaced the filler pipe (plastic insert) and the two o-rings, but not the cap. That was 4 years ago and it has not leaked since. I have the metal cap that came with the Rockster but not sure if that makes any difference.

[DAM650]

timi

where did you buy the plastic insert, mine is blowing oil out the filler hole too

[gregor]

If the oil is actually 'blowing' out that is maybe more than a leaky filler cap. Check the oil breather which goes into the air filter box is venting freely and the engine crank case is not pressurizing. No, I don't know exactly where it exits from the engine. The cap on my 2002 is OK so far, touch wood.

[sstein]

Gregor where is the oil breather found? Do you mean the chamber on the LHS of the bike that needs to be drained once in a while?

[timl]

DAM650, I ordered the parts (filler pipe and o-rings) from MAXBMW.com which has excellent service. Take a look at the fiche for the part numbers. They used to include a packet of M&Ms with your parts.

[sykospain]

Hi sstein,
I got my oil filler lids for various boxers in the past from a firm in Germany called Verholen. Neat little thing with an almost-tamperproof hex-socket and a little BMW emblem.

But Gregor's suggestion of crankcase venting needs a coat of looking-at in your weeping case. The hose enters the bottom of the airbox at a sharp angle and the rubber components on these bikes are only supposed to last 5 years before they are prone to harden-off and split in extreme cases.

That pipe is attached to the air-box spigot with a BMW factory clamp; it needs replacing with a screw-type, the one we call a Jubilee in G,B. when you fit a new pipe purchased at astounding expense from the Greedy Berlin Pig. Or for flumpence from your local hardware store.

The pipe is also known to split at the point whence it emerges from the crankcase, in deepest wires-and-tubes-and-brackets-and-hoses land below the driver's seat. A powerful flashlight is really de rigeur

It also gets blocked with built-up sludge over the years, horrid black gunge deposited from out of the crankcase fumes that are being vented as you tootle along. Explore, Dr. Livingstone....

[DAM650]

i am gonna take a look at that. there seems to be a lot of pressure idling with the cap off, but i have no experience to compare what is regular, and what might be too much

in light of this thread i removed the oil filler grommet (keeper with the slots for the cap, i already have tamper proof unit in place) and cleaned and dried, could not find my black high temp silicone so i dabbed on a little blue locktite to the portion that seats into the head.

voila, no more leaking oil

[sykospain]

Sorted - kushtie...
AL

[gregor]

Thanks for the reply to my vague hint. I'll look out for that hose if I need too. Yes, I did mean a breather into the back of the airbox.

[riceburner]

Make sure you dry off all parts of the filler cap when you replace it after topping up. if you put a wet o-ring back on, it'll weep.

[DAM650]

wow, it's the simple things.

thanks to all

[sstein]

So just to pick back up on this thread, I had noticed that not only was oil weeping from around the filler cap, but it also appeared to be misting out from the rear side of the cylinders. And when I pulled the ignition wire off the spark plug and put of the well, oil dribbled out after it. So I ordered a valve cover gasket replacement set and ANOTHER new filler cap. After installing all, no more leaking, spraying or weeping.

The new filler cap assembly seemed to have much more substantial o-rings. Installing was much tougher and the cap for a much more snug.

[CycleRob]

The leaking/weeping oil film problem after many miles I found was in tiny defects on the finned plastic factory cap and its plastic outer mounting ring. Close inspection of the flat plastic O-Ring grooves OD showed 2 fine casting flash ridges across the groove bottom where the 2 halves of the factory mold came together. When the cap is new, the new O-Ring is able to absorb these small raised ridges for dozens of oil changes and oil top-offs, until the O-Ring becomes less flexible with age. Then oil weeps from some previous dented-in positions, gradually getting progressively worse over time as they accumulate.
It took some 3.0x reading glasses to see and carefully remove those 2 very fine ridges (on opposite sides of the grooves OD) with repeated gentile perpendicular scrapes of a sharp pocket knife blade. Use restraint so you don't remove too much material . . . just enough strokes to make the ridge(s) disappear. Finally, 2 new O-Rings fixed it for good.