I have not started my Jubilee for a few weeks and I was aware that the oil tank contents had almost completely drained into the engine. I started the bike easily and waited few minutes with the engine on tick over and watched the oil tank fill back up. What I had not expected was to see oil pouring out of the clutch/gear-shaft oil seal.
I am at a loss to explain this and I should welcome any suggestions.
The seals are all new. The primary chain case had the correct amount of oil in it on assembly, the crankcase breather is clear and venting. The chain case has a vent on top (non-standard?) and that is clear and venting air, not oil.
I am wondering if, somehow, the crankcase is bathed in so much oil due to wet sumping that it creates hydraulic pressure forcing engine oil past the crank seal into the primary chain case filling it up enough to push oil past the clutch/gear shaft oil seal? Somewhat fanciful and convoluted perhaps but how else is the oil forced out?
What I did not check was if the level of oil in the primary chain case had risen during the leak episode. I may have to wait and repeat the exercise when wet sumping has occurred.
I intend to fit a tap on the oil tank feed line, noting the dire warnings, to see if preventing oil build up in the sump cures the problem.
Dennis
Oil getting into primary chaincase
Hi Dennis
Definitely oil is getting from the crankcase to the primary chaincase when you leave the bike for a LONG time.
I notice that Norton lightweights made after about 1962 had 3 centrepunch dimples around the timing side crankshaft seal. These are to provide extra retention of the seal in the crankcase. The high crankcase pressure when starting with a crankcase full of oil can push the seal out and towards the engine sprocket.
The duplex timing chain tensioner may be held on by two socket cap screws or two studs in later machines. Both tapped holes in LH crankcase go right through the crankcase side, providing another oil path crankcase to primary case.
If you have studs on your tensioner, seal the threads with nutlock/sealer. If you have screws, be aware that every time you loosen and adjust the tensioner, you might be breaking a sealed joint and could consider remaking it.
After that, I'm out of ideas.
Peter
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Hi Dennis, Further to Peter…
Hi Dennis,
Further to Peter's advice I had a similar problem with my 64 Navigator. When I stripped the primary side it was clear that the crankshaft oil seal had hardened and was leaking round the rubber face so needed replacing. I noticed the three peen marks Peter mentioned above and found it very difficult to drift the new seal in thanks to the very slight 'high' that the peening had created which made me rather suspicious of how well it had seated. Luckily I had a few weeks delay waiting for clutch parts and in that time the engine wet sumped enough for me to notice that there was a thin weep of oil leaking past the outer body of the oil seal where the metal surround was not seating properly against the crank case. I removed the new seal and on close examination realised there was sufficient distortion from the peening to stop the seal seating properly in it's recess. I used a soft copper scrapper to ease the seal housing and a smear of Locktight on the outer surface of the new seal holder when I drifted it in and it has cured the problem. I hope that helps - sadly it may mean a primary side strip down again but it might just cure your problem!
Nick
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Good suggestions
Thank you Peter and Nick for your good suggestions. I had not considered the chain tensioner studs as a source of leakage. Also, the crank seal had been peened in heavily before so there may be some distortion around the seat that I need to remove and then seal the outer edge as suggested. I feel another clutch/alternator strip down coming on....
Dennis
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I had similar problems with…
I had similar problems with my crankshaft seal, I’m hoping it’s fixed now, I too had to work the case to get the seal to fit. I try and start my. Bikes every week or so to reduce or stop wet sumping,fortunately neither my jubilee or ES2 wet sump badly.
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Took the chain case apart…
Took the chain case apart today. The clutch/main shaft oil seal lip was peeled over either through oil pressure or incompetence on my part on assembly so that explains the oil leak. I do not have a spare so I will need to order one and a spare from NOC shop.
However, that does not explain how engine oil is filling up the chain case.
The crank case oil seal looked OK but as I had a spare I replaced it anyway and sealed around the metal edge with thread sealant. The chain tensioner stud holes are open into the crank case so I used thread sealant on the studs as suggested by Peter.
It is not all bad as I am getting quite good at stripping down the primary chain case and its contents!
Dennis
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If you are getting pressure…
If you are getting pressure in there, then it must be from the crank case via the shaft seal, are you sure that your vent (the one above the sprocket) is clear? And that the pipe isn’t blocked? There should also be a small hole up near the top of the clutch.
i ran mine without the chaincase cover on to see where the oil was coming from, in my case it was the crankshaft seal.
Dan
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The vents are clear but...
The vents are clear but I will run the engine with the chaincase off to check for leaks. I think the oil "pressure" was from the substantial amount of oil in the sump due to wet sumping. I have now fitted a tap on the oil tank feed line to avoid build up of oil in the sump when standing. I wonder if oil would leak slowly past even a new crank seal into the chaincase over time (months) when the engine had not been run, or possibly leaked through past the chain tensioner studs, now sealed? Alternatively, with lots of oil in the sump, there might be pressure when the engine is started to force oil past the crank seal. I will not test the last theory intentionally as that means allowing the sump to fill with oil! If the tap is effective to prevent wet sumping I might not see the sump full with oil again. Now I need a foolproof way to avoid the tap being closed unintentionally with the engine running. I am thinking of some kind of microswitch connected to the ignition feed.
Dennis
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No leaks so far...
I have reassembled the chain case and no leaks so far. I ran the engine with the primary cover off and could not see any leaks from the crank seal.
What I did notice, and I had not done so before, is that the gear shaft seal needs to be set into the casing quite far back with the outer 'lip' flush with the casing, otherwise, the inner lip is only just in contact with the shaft. There is no reference point for how far the seal should be set into the chain case as there is nothing to stop it going right through the seating hole. I may not have seated the seal back far enough last time.
I am pleased with the tap on the oil tank feed, it is neat and unobtrusive. I used an 8mm gas ball valve that cost just £2.50.
Dennis
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Oil Seal fitment
Dennis:
The next time you have to replace the seal, can you remove the old seal and then take a look in the hole where the seal was riding. I would think that you should be able to see the shoulder on the shaft.
You could then measure how far back from the outer surface (or in from the blind surface if the seal sits in a blind hole) will the lip of the seal be when installed. With that info you should be able to figure out how far to drive the seal in such that the lip of the seal rides on the correct surface of the shaft.
Hope this helps
Mike
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Just realised that the oil in the primary chain case has no where to go when it is below the cutch/ gear shaft oil seal so I used a crude dipstick through the filler hole to check the oil level. Sure enough it is much too high up to half way up the case! I drained about a pint of oil to get the level back to normal.
So it appears that engine oil is getting into the primary chain case from the crankcase. The crankcase seal is new. Could wet sumping cause this problem?
Any ideas?
Dennis