oil feed pipe blew off (tank end under seat)

Hi
I hope somebody could some advice on this - I look after a dear friends Norton. Its an 850 Commando in nice genuine condition 1974 pre electric start in Black / Gold.

I every now and then ride it (not very often) and start it periodically. On starting it this week and on this one occassion i noticed oil pouring from under the seat area - i removed the seat and found the oil pipe to the top of the oil tank displaced hence pumping oil out onto the floor and not recycling back into the tank. I pushed the pipe back on and this time secured it with a jubilee clip as noticed it had just been pushed on before - I topped up the oil in the tank to correct level reading the dip stick on the oil tank cap, ran it and checked again - all appeared fine.

I then thought it would be good to run up for a while and in doing so noticed it had sprung a severe oil leak this time from the under side (like to other end of the earlier secured pipe) albeit have not fully investigated yet. It possibly appears that pressure may be pushing this pipe off - having secured one end may have now pushed the pipe off at the other - is there a breather that could cause this with a pressure relief valve or something of that nature.

The bike is a very nice low mileage example and has never even seeped a little oil let alone what i'm looking at now. Can anybody please advise as your help would be much appreciated.

Kind regards

Dean

Hi Dean,

I'm no Norton expert but I've been running a 75 850 for about 4 years.

The original problem was the pipe coming off.

When you refilled the oil tank you might have inadvertently overfilled the bike with oil. If the bike was lying up for a while it more than likely wetsumped.

Wetsumping might be the cause of the extra pressure. When you topped up the oil tank there might have been a litre or two in the sump & when the oil starts circulating it starts coming out!!

I'd drain the sump to see how much oil is in there. I'd also drain the chaincase as oil can migrate from the sump into the chaincase causing overfilling in the chaincase & more oil leaks.

Hope this helps

Kevin

The oil tank has a breather, therefore, technically it should not possible for pressure to build up in the the oil tank.
Are you sure all oil and breather pipes are fitted the correctly? Check that the engine breather and oil tank breather pipes are not swapped over.

I suggest you compare the oil and breather lines with the lubrication diagram.
http://www.oldbritts.com/oillines.html

The Old Britts website has a pictorial illustration of oil flow here.

From your description it sounds like you are referencing the engine breather line. If so, it might be worth mentioning that I had jublilee clips on both ends of my 1975. Still, since this is new behavior, I would try pushing a probe through the metal pipe at the tank to make sure something hadn't blocked it off. Then I would check the line that vents the tank to the atmosphere (shown as oil tank breather). I suggest that since if that was blocked the next easy path, such as blowing off another line, would occur.

Edit: others have beat me to it.