main seal.

I remember seeing some talk about these seals. My existing one is the steel type. Is there a better type to buy. Cant seem to find the bugger I bought 2 years ago that was supposed to have an oversized rubber outer diameter.
regards, Dereck

The rubber covered ones tend to seal better, the metal ones can let oil past where the metal sides press into the recess. If I had to use a metal one I would put some sealant on the metal edge.

If the crankcase is pressurized you will probably have problems with a leaking crankshaft seal. Looking for a better, magic seal is not the answer. Getting rid of the crankcase pressure is the answer. There's a ton of info on crankcase breathers on this forum.

If you are running a stock setup I cannot see how you would know it is leaking. Was only when
I put in a belt that I noticed the bottom of the case getting oil in it. Im at the teaspoon for
150 miles now. Not a lot but enough to be a pain.
Worst part is I have a sump valve installed.

You know it's leaking with the stock setup when you remove the level plug on the primary cover and several cups of oil squirt out. Then put the plug in and ride it fifty miles, remove plug and oil squirts out again. Blown seal.

Glen

I see, blown seal v. leaking seal.

Onder said:

I see, blown seal v. leaking seal.

Click to expand...

Right, I see your point, a leaking seal would be harder to track. Depending on the rate of leakage, it might take a fairly big mileage to show up in the primary level. And I suppose if it was a small enough weep, it wouldn't really matter, just a few extra drops of oil into the primary every trip.
My blown seal was my own fault. I started the bike with a full sump and even though I rode off fairly gently, must have revved it too high too soon. The seal stayed in place (MK3 with snap ring) but the centre portion turned from an iny to an outy.

Glen

If you run tranny oil you will soon see if there is motor oil mixed with it, depends on how much.

Ashley

Onder said:

If you are running a stock setup I cannot see how you would know it is leaking. Was only when
I put in a belt that I noticed the bottom of the case getting oil in it. Im at the teaspoon for
150 miles now. Not a lot but enough to be a pain.
Worst part is I have a sump valve installed.

Click to expand...

when you add 200 mls of oil to the engine, and remove 200 mls of oil from the primary drive housing, you have a fair idea its coming from the engine either via the seal or the 3 bolts holding the primary to the engine.. When you cant drain the primary housing, you end up with oil all over the underside of the bike, too much on your chain and an oil soaked tyre. When you ride for 13 hours without draining the primary I can assure you it makes a mess.

I have known that seal was leaking for several years, and riding from home for an hour or 2 was never a problem. I didn't have time to do the seal before the rally, but its in bits right now waiting for a new seal. From what I see, the seal still looks like it should.
As for engine pressure, I have a large one way valve in my breather, and since fitting new pistons 10,000 miles or so ago, the bike is going like a train. I don't have any oil leaks from above the crank level.
Dereck

My experience is that in certain instances where a metal rimmed seal has leaked, replacement with a rubber rimmed seal has solved the problem, both seals are available from various Norton parts suppliers. This doesn't negate the necessity for the various breather requirements, but it does help.

The Maney seal is rubberized and worked for me. It is a single lip as I remember. Check surface of shaft for any damage. Mine had a nice scratch from a previous removal process. I had to lap down the seal body to make it seal in a new place on shaft. Any attempt to reduce crankcase pressure will help with this.
Mike