Seapage around oil filler cap

[slowtorque]

My 04 1150R occasionally does not seal properly at the oil fill plug and now I have a friend with a R12C (2000) that is doing the same thing. My feeling is that the o-rings are just getting old and need to be replaced. I see only one which fits over the cap. Am I missing something here? Thanks

[jas]

Remove the cap and replace the o-ring, set aside. Stick your finger or two inside the fill hole. There is an insert tube that is connected to the valve cover and it just snaps in and out, you do not need to remove the valve cover. This is what the oil filler cap snaps into. once you get your finger in the hole, hook it and pull straight out, once out, you will see the second o-ring. This should take 5 seconds tops!

The insert can warp and not seal if it gets too hot, but usually it is just the oring that needs replaced. If you get an aftermarket fill cap and tube/insert, you will need to pull the valve cover to get to a setscrew that hold the insert insde the cover.

I replaced both orings every second oil change. Not needed, I understand, but I rode a lot in the rain and did not want to provide a path for the water to get into the oil.

[sjbmw]

The stock oil cap leaves a lot to be desired. I got one of these years ago, and it's worth it.

http://www.ascycles.com/detail.aspx?ID=33528

[Dr. Strangelove]

Before you spend money, try this CycleRob tip: Dry both surfaces as completely as you possibly can. Really Really dry. Worked 100% for me when mine was weeping. Now no weeping at all.

[slowtorque]

I think I have worn that trick out, the drying all surfaces. Thanks, though. Plan to freshen up both o-rings and inspect the plastic bodies. I can't tell much about the A&S cycles version. Is it of a better design and not likely to present the same issue over time?

[jas]

I did the Cyclerob cleaning and it worked well, and before the o-ring were installed, gave the insert and cap a soap bath. This worked well for my 40K miles. A friend has the complete AS unit (insert and cap) and it too works well. Just more than I wanted to spend.

[sjbmw]

I think I have worn that trick out, the drying all surfaces. Thanks, though. Plan to freshen up both o-rings and inspect the plastic bodies. I can't tell much about the A&S cycles version. Is it of a better design and not likely to present the same issue over time?

The AS cycles version is a BMW product. May be able to get it cheaper elsewhere.
I have been using it for 7 or 8 years now. It's a locking cap, so nothing "weeps".
(The lack of pressure by the plastic may have as much to do with seepage as the rings.)

One of the issues I had with the stock plastic cap was a little paranoia based, as anyone in 5 seconds can toss crap in your oil with the stock cap.


Yes, we do have vandals in my part of the country.

[bergj1986]

I experienced many leaks with my oil cap as well. After replacing the o-rings a few times and the seal only lasting a few thousand miles, I removed the black, plastic piece that the oil cap seals into (using the finger-hook technique mentioned above), installed new o-rings, and put a light coating of high-temp silicone around the o-ring. Make sure you have the hole clean of any oil and other debris so the silicone seals properly. Pop the plastic insert into the cylinder head and let dry overnight.

[slowtorque]

Sounds like great advice. Plan to follow this weekend.

[CycleRob]

When my OilHead was near new it started weeping oil too, even after paper towel cleaning. Removing the plastic outer housing revealed why it was weeping. There were 2 opposing casting flash joint seams sticking up inside the O-ring channel. A seam is necessary to release the part from it's mold in order to manufacture a part with those contours, but that seam should not be big enough to be felt. It was the equivalent of a fine wire running perpendicular to the O-ring, allowing oil to slowly weep past it. That's very likely why "They all do that". Careful, patient scraping with an Exacto knife blade got the sealing surface matching the rest of the channel's groove. I just looked at the whole assembly, given to me in person by a board member who went to an aftermarket Aluminum one, and there are 2 such seams still there, barely visible on the groove's floor. I will bring this unmodified part to the May Bash for show-n-tell.

Using Hi-Temp RTV gasket sealer (available at most Auto Parts stores) on the outer ring's sealing surface to the valve cover will improve the oil integrity and help keep it in place. Just give it a day to cure. Be aware that there is an alignment tab that must fit into a square recess in the valve cover AND it takes a lot of force on the big 7/8" half inch drive socket (used as a installer/driver on the plastic part) to "pop" the lightly greased O-ring fully into it's channel on the valve cover.

That ended the weeping for good, and I sold the bike 8 years later with it's original high quality made-2-last fat O-rings still in place. Not adding oil between changes after the 18K mark or allowing the engine to excessively overheat helped minimize damaging both O-ring's good sealing capabilities.

[Cohiba54]

slowtorque - i went throu all the tricks mentioned, some woked fow a while longer than others. Using a gasket sealant did last longer. And here it comes BUT the leak (weeping ) came back and was pita to clean of. So do what i did, go to your beemer shop spend the $15 for all new parts and be set for another 20k miles.

[slowtorque]

Update: on my R1150R, I removed the filler body from the engine casting and found the sealing o-ring a bit gritty. Cleaned it, dried it and reinstalled after treating the plug o-ring the same and no leaky. My friend's R1200C, well, that was actually a little worse for wear. I bought a new filler body and plug and both o-rings for it. Turns out the filler body was badly warped and was not going to seal regardless. So new parts have solved the problem. Thanks to all.