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Oil leaks from my Jubilee

Submitted by dennis_thompson on Thu, 16/08/2018
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Light Twins

To my horror, my newly restored 1964 Jubilee engine is positively haemorrhaging oil from every orifice!

I fitted new gaskets and oil seals throughout and even used Loctite 5699 grey silicone on the primary chain case. I have used this successfully on many other bikes.

I now wonder if I have overfilled the primary chain case? The manual I use states: "Fill the case with oil until it just runs out of the filler hole." That is a lot of oil and means the chain case is half full of oil, possibly above the new rear drive sprocket oil seal (another leaking item). The breather (?) in the top of the chain case is not obstructed so I doubt there is any pressure build up. I have not had the engine running yet so it looks like gaps in mating surfaces are the main problem.

One good point is that I primed the engine with oil by turning it over on the kickstart until I saw oil return to the oil tank. It took a while but it is now gushing back into the tank. I had the oil pump overhauled so that is a good sign. I also see oil flowing to the rocker feed.

So far (fingers crossed) the gearbox seem oil tight.

Many thanks,

Dennis

Submitted by patrick_mullen on Thu, 16/08/2018

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Dennis,

I think you have vastly overfilled the primary chain case. The manual should say " engine oil should be poured in via the inspection hole until it commences to drip out at the level plug hole."

It only takes a minute amount of oil. I don't know the precise figure- maybe half a pint or less.

Patrick

Submitted by dennis_thompson on Sat, 22/09/2018

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Whilst waiting for a replacement electronic ignition module to arrive from New Zealand, I thought I would sort out the horrendous oil leaks on my newly restored Jubilee engine.

I stated elsewhere that I was disappointed with the crankcase gasket that was supplied in the engine gasket set as it simply did not fit. In the end I dispensed with that gasket and used Loctite gasket compound. I also used that compound liberally in conjunction with gaskets on the gearbox and timing side covers. So far so good, no oil leaks.

I did get oil leaks from the rocker feed unions but some fettling with copper washers seems to have cured them.

I was not happy stripping and re-building the engine again and it took a couple of weeks on and off but it seems to have been worth it. So with new gaskets and oil seals the engine looks oil tight for now.

Dennis

Submitted by dennis_thompson on Wed, 17/10/2018

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I spoke too soonCry

A new problem appeared. It took me a while to cure the rocker feed banjo oil leaks. Both banjo bolts (one oversize and home made) appeared to be too long. Having shortened them I still resorted to gasket compound and new copper washers.

While I was at it I inserted a clear plastic tube (Biro outer cut to size) in the rocker oil feed line as I wanted to make sure that oil was flowing after the fix. That worked fine.

Feeling smug I ran the engine for ten minutes to set up the carb and found a pool of what appears to be gearbox oil under the drive sprocket. I must have damaged an oil seal when I stripped the engine the second time; they were new oil seals.

I have ordered sleeve drive, clutch and crank oil seals x 2 and I look forward to removing the clutch case again, not!

Will this never end?

Dennis

Submitted by dan_field on Wed, 17/10/2018

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If you run the engine with the clutch cover off, youâll be able to see if the crank seal has gone allowing excess oil into the chain case. That was the source of my oil spray all down one side! I now have the leaks under control, but the once oil tight sump plate is now leaking a bit as is the kickstart/gear leaver shafts, they never seem to stay dry for long, Iâm seriously thinking about have the cover machined for a proper seal!

Dan

Submitted by dennis_thompson on Thu, 18/10/2018

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Dan and Robert thanks for the tips.

I had some trouble fitting the crankcases together and inserting the gearbox internals, both went together abruptly when things were lined up. That could have damaged either seal so checking the crankcase seal with the clutch cover off is a good idea.

The rocker cover banjos are now sealed so I won't disturb them but I will check the mating faces next time they are off.

Regards,

Dennis

Submitted by dennis_thompson on Wed, 31/10/2018

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Fingers crossed I have stopped the major oil leaks.

I think the problem of oil from the chain case was because I used a Tee piece to connect the engine breather and chain case breather together as there is only one return pipe to the oil tank. The other pipe is the tank breather.

With the chain case cover off (thanks Dan) and the engine running I could see no oil coming from the crank seal or the gearbox main shaft seal but Oil was coming back into the chain case via the breather. It looks like the air flow from the crankcase breather was forcing oil mist back down into the chain case.

I am not sure the chain case breather is really necessary as it was not fitted to earlier bikes so I disconnected it from the Tee piece, leaving the crank case breather only going directly to the oil tank with its own pipe. I left a stub of pipe on the chain case breather to see if oil or oil mist comes out of that. If it does I might use it as a chain oiler Laughing

I replaced both oil seals in the chain case anyway as I had the case off even though they were new.

So far so good.

Dennis

Submitted by nicholas_clarke on Wed, 31/10/2018

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Hi Dennis, I have a standard 1964 Navigator and I have owned one of the very last post 64 Jubilees to leave the factory and neither had a primary chain case breather and it isn't mentioned in any of the manuals or spares books that I have! There is a crank case breather which is a short metal pipe which exits the left hand crank case just above the final drive sprocket and has a rubber pipe which goes to the top of the oil tank. There is another oil tank pipe exiting the top of the tank which connects to a second rubber tube which routes down to a hole at the front top of the chain guard which acts as chain lubricator. In my humble opinion it seems someone has modified your engine or primary chain cases - the primary side shouldn't need a breather because it shouldn't be pressurised if the drive side crankshaft seal is working! Could you provide a photo to throw more light on the subject?

Cheers

Nick

Submitted by peter_holland1 on Wed, 31/10/2018

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I agree with Nick.

The standard breather for the primary drive case is a tiny hole, about 1mm diameter, in the inner case, behind the clutch, and above the sleeve gear seal. The case is thickened at the point where Norton/AMC drilled the hole.

If you decide to block the breather that someone has added to the primary chain case of your bike, you might consider it wise to copy the original 1 mm diameter hole. It will let air out as the chain case warms up and prevents a partial vacuum as it cools.

Peter

Submitted by dennis_thompson on Thu, 01/11/2018

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Thanks both. Yes it might be that someone has modified the inner case although it looks like a professional job, properly threaded and rebated slightly.

The 'real' breather, the small hole at the back of the casing near the alternator wire outlet hole, is clear so I doubt that the chain case would be pressurised under normal circumstances. I was however surprised at how much air/oil mist was being pumped out by the crank case breather. If even a small proportion of that force was going back down into the chain case it would probably overwhelm the pin hole breather and add oil slowly to the chain case maybe even forcing oil past the gearbox shaft oil seal.

Photo is attached.

Dennis

Attachments
dscf2625-jpg

Submitted by nicholas_clarke on Thu, 01/11/2018

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Thanks for the photo Dennis, that is definitely a modification which frankly shouldn't be needed if the primary side crankshaft oil seal is doing it's job stopping oil and 'blow by' gases flowing from the crank case into the primary chain case. The pin hole breather at the back of the chain case is only there to allow for the natural expansion and contraction of the chain case air and oil as it heats up and cools down to vent to atmosphere. As for the crank shaft breather there is always some oil vapour and pressure fluctuation from the 'pumping' action of the pistons and slight 'blow by' of exhaust gases past the rings venting into the oil tank but if the pistons, rings and bores are in good condition this shouldn't be much. Did your engine rebuild include a re-bore, new pistons and rings and were the rings spaced so their gaps are 120 degs apart to minimise blow by? If not or if the blow by seems excessive it might be worth doing a compression test. Good luck, keep at it you are getting there!

Nick

Submitted by dennis_thompson on Thu, 01/11/2018

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Nick, yes the engine was re-bored and fitted with new pistons and rings and compression is good.

Perhaps the crankcase venting is not excessive, I just did not know what to expect. The crankcase breather had actually been blocked off by a previous owner and I did not know it was there until I read about it on this forum. Hence the shiny copper pipe seen in the photograph that I put in when I drilled out the plastic filler blocking the vent.

I don't suppose a blocked crankcase breather would help when trying to cure engine oil leaks.

I have just applied to the DVLA for an age-related registration with help from the NOC records officer.

Dennis

Submitted by nicholas_clarke on Thu, 01/11/2018

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That all sounds very hopeful, don't be surprised if there is a little more blow by and oil vapour venting whilst it is running in - it takes time for the rings to bed in. No wonder it was suffering oil leaks if the crank case breather was blocked off - it would inevitably tend to blow past the crankshaft oil seal pressurising the primary chain case and over filling it with oil. Perhaps that explains the previous owner modifying the primary chain case to have a breather! Good luck with the DVLA and getting it on the road - I really enjoyed my late Jubilee back in the day!

Submitted by dennis_thompson on Fri, 02/11/2018

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Nick,

Many thanks. In fact I took the chain case off again today (!) due to small weep of oil. The inner casing is a poor casting with some pitting. I used lots of Loctite 5699 this time Cry

I'll post some pictures in a new post when the bike is finished.

Dennis

Submitted by nicholas_clarke on Fri, 02/11/2018

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The NOC shop has a late, 64 on inner chain case for sale at a very reasonable £10 - it might be a worth while investment if yours is in such poor condition! Good luck with the rest of the re-build and looking forward to seeing the photos! By the way the correct colour for a late Jubilee is a lovely semi metallic red that Norton's sales people called 'flamboyant burgundy'! Mine looked fantastic in it with the optional extra chrome mudguards - sadly it was stolen in 1986 and never recovered.

Nick

Submitted by dennis_thompson on Sun, 04/11/2018

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Nick, good to know that a chain case is available from NOC; I hadn't spotted that.

My paint job is not original as I am not after a period look. You will understand why when I post some photos Embarassed

Dennis

 



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