[Maturin]

On my way to the annual German Enfield rider´s meeting I was stopped soon by a blown gasket.
After 2 km Autobahn I looked into the rear view mirror to see a huge smoke cloud behind me. Looking down on to the engine I could immediately see the cause: Oil pumping out of the filter´s cap, dripping onto the exaust and silencer.
As tightening the screws a little had no decisive effect I left accross country to hobble back home with the dripping engine.
That is (again) an issue of maintanance: I didn´t replace the gasket on the last oil change, neither I replaced the o-ring in the filter cap that is located in a groove. Maybe my dealer, who made big mistakes maintaining my bike, didn´t change them either.
Well, i just found out they don´t have eternal life. I recommend changing the gasket as well as the o-ring at every oil filter change, they´re penny articles, and iIt´s necessary to take original parts. I tried a selfmade gasket made from 0.50mm gasket paper, but it´s still sweating pretty much. The stock part is made of plastic and probably stronger. Another issue are the 8mm bolts I really don´t want to twist off.
I also tried to use sealing mass with the blown gasket, but to no effect. I guess, the o-ring is the key part here. It could be his job to detain the oil pressure from the gasket. If it has not enough tension to do so there is probably no way to get it tight anymore.
I immerdiately ordered two sets of gasket & o-ring for 3,60 Pounds from Hitchcock´s. Small fee, but as long as I don´t have them the bike stands. Bummer.

[Arizoni]

As you probably know, a O-ring packing is the most effective means of sealing a hydraulic or pneumatic system as long as the packing is in good condition.  They are far more effective than any form of flat gasket except perhaps for metal gaskets with elastomeric seals cast into them.

Unfortunately they are made out of easily compressible elastomers which can be cut or torn when they are installed.

We at Garrett Turbine Engine Company (now Honeywell) found that the sharp corner or edge where the lead in chamfer meets the bore would on occasion cut a O-ring during installation.
Because of this we adapted a policy of requiring that  these sharp edges must be rounded off with a small radius.  Just enough to remove any sharpness.  We even went so far as to develop a machining standard which specified the sizes and blends of the radius.

Getting back to your problem (and everyone else who wants to head off a potential problem), I suggest that you buy a sheet of 400 or 600 grit wet/dry sandpaper (actually black silicone carbide) and tare off a small piece.  Using your thumb to provide a backing and some pressure lightly sand the corner where the chamfer meets the filter bore. 
If you do this, be absolutely certain that you have wiped all traces of the tiny pieces of metal and any of the silicone carbide grit that may have fallen off of the paper out of the bore and off of the adjacent faces.  Not one small piece must be left in the area as this is on the downstream side of the filter and it will be carried into the critical areas of the engine.

Also, when installing your filter cover with its new packing be sure to lubricate the chamfer and the outside of the packing.  A little oil on these surfaces will greatly ease the installation.

[Kevin Mahoney]

Good advice! We always include O-Rings in our oil filter change kits. However it is all in the installation. I also like to use something like grease to hold them in place when installing

[Maturin]

Thank you very much for this advice, Arizoni, and for sharing your obviously vast experience.
As the bike stands I have enogh time I´ll follow your instructions thoroughly.
I remember having ignored a tiny amount of oil mist around the filter cap for some time because I wasn´t sure where it actually comes from. It turned out that this was a mistake, the cap must be 100% tight. When the oil starts to bubble out you´ve got a major party-killer because right behind the cap the full oil presssure is accumulating. Within ca.10km I lost about a liter. I sincerly hope I didn´ruin the low end, running it home with reduced oil pressure  

[barenekd]

The bottom end still as its oil pressure as long as the pump can pick up oil.  If you run out, then the bottom end will suffer.
You should be OK.

Bare

[Arizoni]

As a side note about low oil pressure I was talking to my dealer about the cloth-like material I found on my sump oil pickup screen when I did my first oil change.  I was concerned that it might have reduced the engines oil pressure.

After hearing my story and concerns he said (in so many words), "You didn't have low oil pressure.  If you had low oil pressure you would have known about it immediately. 
In these UCE bikes, if there is low oil pressure the hydraulic valve lifters will collapse and it will sound like someone is in there with a full drum set beating on their drums!"

Makes sense to me, and it's a good thing to keep in mind whenever your valves suddenly start to clatter like hale beating on a tin roof.

[olhogrider]

The rag is inserted in you crankcase at the factory to collect more stuff on your first oil change. Also your dealer can tell if you actually did the first oil change since the rag would be removed by you. If it is still there, you didn't change the oil.

Of course, I'm kidding. It is probably gasket material. They all have it on the first oil change. After that, you should only find bits of metal on the drain plug. 

[singhg5]

That is (again) an issue of maintanance: I didn´t replace the gasket on the last oil change, neither I replaced the o-ring in the filter cap that is located in a groove.

Well, i just found out they don´t have eternal life. I recommend changing the gasket as well as the o-ring at every oil filter change, they´re penny articles, and iIt´s necessary to take original parts.

Thanks for the recommendation and warning that the gaskets and rings are not made to last forever - they do need replacement. There is no substitute for experience. It happens to all of us that we ignore or pay less attention to somethings that can cause bigger problem. 

Since you did not hear any terrible noises on your way back, it seems your engine has survived this mishap.

[Maturin]

If you take out the oil filter and look inside it´s chamber there´s another o-ring that tightens the filter to the rear wall. It´s certainly not as important as the outer one, because the filter is pushed inside by the cap apparatus anyway, but it strikes me as a good idea to change it aswell regularily.
Just wanted to mention it, this o-ring may easily be overlooked.