Oil Leak through Timing Cover

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Apr 29, 2005
Gents, from reading some of your posts this might be an easy question to get answered. Have a 73 850 Roadster. Ride it every two weeks for a 100 miles or so. Yesterday went in the shop and had about a 1/4 pint of oil on the floor. Feels like its dripping out of the timing cover. Any ideas on what is happening here?? is there something I need to tighten or is there an oil seal I have to replace?? If so what is the difficulty involved. Appreciate any input. Semper fi devildog

71 Commando Hi Rider
73 Commando Roadster

Not likely to come from the timing cover mating surface if it has not been disturbed. Check the rocker feed oil line and the banjo going into the timing cover. The stock nylon lines tend to harden and crack. They can be replaced with air brake hose from your local diesel mechanic or a more permanent solution is the stainless braid hoses most British shops supply.

Another slight possibility is the cam seal in the timing cover. However, I have never had one suddenly spring a leak without having removed the cover, and then not that much oil.
Seems a bit odd for the timing cover springing a leak without you doing work on the bike. Could be the oil seal behind the points, the points cover has a hole to allow any oil that gets past the seal it to leak out but 1/4 pint is way to much for this. Could be the oil tank base which does have a pronouced tendancy to get an unseeable hairline crack on the weld on the bottom mounting, this looks like a gearbox leak normally.

RonL/Kommando, Thanks for the tips, have to get it up on a table so I can see what is going on with it. Again appreciate the tips. semper fi devildog
Oil Leak Problem, More Info

It has been about two or three weeks since I started or ridden the bike. The leak just started about three days ago so it basically sat for two weeks and no leaks and then two/three days go started leaking. Need to check it out tonight and let ya'll know. tks devildog
timing cover oil leak

If you haven't started it and the leak just happenned it could be due to oil wet sumping (draining out of the oil tank into the crankcase passed the oil pump). That doesn't identify where it's coming from, but could be why. Look over the bike and find where the oil is coming from.

If it is wetsumping, remove the oil drain plug on the bottom of the crankcase and let the oil go into an oil pan. If that stops the leak, you've found the cause if not the location.
dave, Kommando, Ron, well went out to the ranch last night to check on the 850 with the oil leak. Same thing a big 10x14" puddle of oil under the bike. Pulled the ignition cover off and the oil is coming out or seeping out of a little hole in the bottom of the ignition cone. So then here is what happened----- first I havent started the bike in over two weeks. Prior to starting the bike, I checked the oil level--- it wasnt registering on the dipstick. I then added TWO quarts of oil before it registered on the dip stick. Now for the big surprise. I started the bike, which also starts on first or second kicks just like all good Nortons do!! I drove it about a 100 yards and as I shifted the back end spun out--- I slowed down, looked back and saw a trail or oil. It naturally was coming out of the overflow tube from the oil tank resevoir. I was at a point of no return so just kept going and finally it pushed all the excess oil out. So with that info, I guess the oil that is normally held in the oil tank seeped past some seal and was all down in the bottom of the engine. As I stated I am not an experienced mechanic and have to read the manuals to do most things on the Norton's. Again any input on this would be appreciated-- is the problem major that I should be concerned about or can I just keep running the bike with the oil drip. Oil drips dont bother me as you might can tell with me running Harley's for so many years. Tks for any help. Semper fi rod Jason, you still out there??
It sounds like your problem is simply overfilling the oil tank. Before checking the oil always run the bike for 5-10 minutes to return any oil from the sump. Keep the level on the dipstick BELOW the "H" mark. I always shoot for the midpoint.
Most Nortons will wet sump if left for two weeks or more. Some more than others. This typically does no harm. In your case, it filled the crankcase above the camshaft and leaked out the camshaft/timing cover seal. Without overfilling the oil tank, I doubt it would normally reach this level. If it continues to be a problem, the timing cover should be removed and the oil pump serviced by disassembling and dressing all surfaces to insure a tight fit. A new gasket behind the pump and a new spigot seal would also be in order at this time. Then I would replace the seal in the timing cover and be sure to use a guide when replacing the cover. Finally a new timing cover gasket should be used. This should take care of problem, however, on long periods of storage it will likely still drain some oil to the sump.
The scavenge side of the pump is significantly larger than the feed side, so running the bike with oil in the sump will simply return it to the tank within a few minutes. However, if the tank appears completely empty, drain the sump before starting the engine and refill the tank. Do NOT start an engine if the oil tank is completely empty as the bearings will not receive oil until the scavenge side can start returning oil to the tank.
Thanks Ron, this all makes sense and follows exactly the sequence of events. Any advice where I can order these seals and gaskets--- also are there any special tools I will need. I have a well stocked shop but have no special Norton tools. Have a good weekend. semper fi rod

If you plan to change the camshaft seal, you should consider buying / borrowing a seal guide. This is a tapered spindle that screws onto the end of your camshaft. The spindle OD nearest the camshaft is the same diameter as the cam. It then tapers down to a diameter that matches the seal ID. This tapered spindle provides a gentle ramp for the seal to glide over when re-installing the timing cover. Without it, you will damage the seal on the rather sharp edge on the end of the camshaft.

Semper fi

Save the money use a nice chrome socket. It isn't tapered so it will need to be just a few thousandth's Over size like plus .010 beyond the cam shaft size. You will need calipers to find the right size socket and lots of old sockets to choose from.Just lube the seal put the socket in the seal put the cover on letting the cam slide the socket out of the way. Make sure you get the right size conical seal for the oil pump that is messed up by beginers all the time. I would not assume that the seal is bad by the way no seal can hold back all the oil you had in that motor. It's a dry sump system and run right it dosen't leak unless you have lots of blow by from the rings. Work less ride more tis the season. norbsa
Oil Leak

Gents, well after taking all your input I believe the problem was that the oil just got by the seal and leaked out through seal around the cam and ignition. I say this based on the fact that the bike had set for 2-3 weeks. I road it a hundred miles or so last week and its not leaking now. It has been sitting for three days now. Seeing that there was no oil registering on the dipstick, I should have only put a 1/4 qt in the oil resevoir, started the engine, then road it and all would have been ok. Will see how things goes. Again thanks for the good advice. Semper fi devildog
It's been said in a previous post, but I'll repeat it, because from your last post, you're scaring me :( :


...and then all will be well.


Oil dripping through Timing Cover

Derick, thanks for the response. I could have probably worded it better but my statement about adding oil would only be a little bit to take care of the engine for the 15-30 seconds it would take for the oil in the sump to be returned to the tank. I made a mistake the last time by adding oil without the understanding the oil was in the sump and not knowing how much had leaked out through the timing cover. I got it under control now, just was not familiar with situation which seems to be normal on many of the Norton's of that era. Again thanks for the input. Semper fi devildog
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