Timing case leak

Keep asking - cos I'm learning too!

Previously George Phillips wrote:

Sorry that I seem to be hogging this forum but just when I thought everything was generally OK I find oil hissing out from the joint between the back of the timing cover and the Lucas magdyno (up the top at the drive end). My spares book doesn't show any seal there so what stops oil escaping? Could it be that there is no seal and I've got a blocked timing case drain? I don't want to start stripping it all until I know what I'm looking for. Thanks for any help.

Similarjoint on minehas a largepiece ofcarpet felt set in there. dont have it touching the shaft just a ring of thestuff. Though "hissing" out suggestsitspressurising. First offI would check yourbreathersystem and thequantity of oil in your crankcases....

There isn't a seal but there shouldn't be enough oil in there to leak out. Should only be a mist of oil to lubricate the timing chain. Should also be a breather at the bottom with a metal pipe that lets any excess oil drain away.I wonder ifthat breather could be blocked? My '55 ES2 gets virtually no oil in there, to the extent that I occasionally lubricate the timing chain manually.

I like the carpet seal solution but some proper felt would be nicer.

Hi George. Just been out in the garage and checked mine. There is a gap of at least a 1/16 inch between the mag and the back of the timing cover. Have now completed 750 miles over winter since its rebuild and not a drop has appeared around that area. As I understand it oil mist is meant to pass the inlet cam bush, lube the mag chain then any excess to to vent off from the pipe. I have owned 6 ES2's over 45 years, all have dripped from the vent pipe but none have ever leaked oil from the mag. area. John

If the drain isn't blocked then there is an excess of oil entering the area via the cam bush.

If it's greasy and gungy then I'd suspect that a previous owner has filled the whole chain area with grease which is not the intention at all.

If you use a long pointy thing to retain them then it is quite possible to remove the timing cover without disturbing the cam wheels and timing...but if the bushes need replacing and reaming then it probably will be necessary to remove everything as the bushes in the crankcase will be worn too.

My first step would be to remove the chain cover, give everything a clean and reassemble with nothing more than a fingertip of grease along the chain run. It doesn't need a lot - vintage magneto chains ran exposed.

I think I'm right in saying that the oil pressure relief valve lets oil into the timing case, and from there into the mag chain case if it is blowing. Although this should drain out of the pipe at the bottom, so shouldn't cause your problem so long as the pipe isn't blocked. It might be worth you investigating this although it will require removal of the timing case, which in turn will require the mag chain coming off......... . Perhaps do the other simple checks first!

Nice one George. At 102 posts, this thread has run and run ! Luckily the singles sub-forum is a well behaved and friendly place

That's very good news George. It has got to be the line to investigate on my 19S just as soon as I stop riding it this year. Hopefully I will be one of those members to benefit from your experience.

Cheers, Ian McD

That probably also means that the big end was being starved of oil as it all went straight into the timing chest......

But I agree with others this has been an excellent thread. I always prefer to learn from others' mistakes than my own!

On the positive side, it seems that excess oil coming from that mag chain overflow may be a good indication of problems in the oil feed system.

Is it the PRV that helps to stop my M 50 wet sump?.............or am I just lucky!

Regards John O

Thanks George, that is very encouraging. I will be investigating the PRV on my 19S in the near future. Will be very happy if I can obtain a similar result (and hopefully without some of the complications you encountered).

Cheers, Ian McD

Great result and thanks for reporting back.

Hi George,

Have you checked the inlet camshaft bush? In my c ase, I have to turned a new one, because it had too much side play.

Unlike the exhaust camshaft, the inlet camshaft drives the magdyno chain, which sometimes could have been set too tight.

The exhaust cam bush has a spiral groove for lubrication along the entirely lenght, while the inlet camshaft bush reaches only half way from the inner side, thus avoiding any excess of oil reaching the magdyno chain area.

Hope this help.

Hans from Chile.

P.S. Attached a photograph of the new inlet camshaft bush. (on the right).

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There isn't a huge amount of oil inside the timing cover so there shouldn't be too much getting through the inlet bush. As you say, this is the only way oil can get in. I wonder whether you have slight wet sumping, and also whether your crankcase breather is working properly. If the crankcase is getting pressurised this may force oil out through the bush especially if you have been a bit over enthusiastic in reaming it.

Did you make sure the slot in the inner end of the bush was correctly orientated?

I thought I had a diagram somewhere but can't lay my hands on it. The bushes have slots in their inner ends which need to be at a 45 degree angle but I can't remember which way round they go!

My diagram is probably if EM Franks's book which I only have in grubby hard copy.

As I thought it was Edgar Frank's book, although he doesn't actually show the inlet bush in the timing cover. I would guess that the groove needs to be at right angles to the one in the timing chest however (not 45 degrees as I had thought). But someone will know better.....

Note what he says about the oilway being blocked off in the inlet bush.

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I don't really know and there's nothing in the book to tell us. It's the only place I've seen that information - the official Norton book doesn't mention the bushes other than to say your dealer should fit them, and the Haycraft Pitman book, although generally helpful is equally silent.

hello, i dont expect a reply. but heres a photo of my 56 19s crank case showing oil holes in tops of the bushes

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Hi George, I'm following this with interest - as you know I have the same problem with my 19S. Sorry to hear that the new bush did not solve the problem (but spares me a job!). The bush orientation highlighted by Ian sounds promising.

Some years ago Mike Pemberton overhauled the bottom end of my engine. Because of the oil loss from the inlet camshaft I asked him to check the condition of the bushes. He reported that they were in good condition and did not need to be changed. He reset the pressure relief valve as he said it was screwed in tight and would not have operated as intended, resulting in high oil pressure. After this work the rate of oil loss past the camshaft bush actually increased significantly. When the relief valve opens the excess oil is delivered to the camshaft gears so I wonder if part of the problem comes from an over supply of oil to this area.

Ian has also mentioned crankcase pressure as a possible contributing factor. I am not ruling that out but I have tried running with the standard one way ball valve, with an open breather, and with an Enfield "duck bill" tube on the breather pipe. I didn't notice any significant difference to how quickly the catch bottle filled. It might however be worth trying more sophisticated breathing arrangements involving reed valves that have been suggested in other threads on this site.

Ian McD

I'm suspecting that the oil groove(s) in your inlet cam bush actually extends all the way to the end, which would allow the oil to pass straight into the mag drive. I'm interpreting Franks's comment to mean that the spiral groove should stop short of the end of the bush.

You can see from Barry's photo that the grooves in the crankshaft bushes go all the way through. If the inlet one in the timing cover is like this it will allow loads of oil through - and you may even be able to feel crankshaft pressure pulses on the end of the little drain pipe.

It should be possible to fill the grooves with solder. You will need to clean off all traces of oil first. Easier with an uninstalled bush. You may have to apply the reamer again, to clean off any overspill.

Don't forget that the top end is fed with oil from the return side of the pump, so pressure adjustments on the feed side unlikely to affect the quantity reaching the top end.

I have also wondered if leaks from the pump, either from the pump/crankcase surface or from where the pump outlet spigot meets the outer case (fibre washer) could result in too much oil reaching the timing gears. Do you know if yours has a paper gasket behind the pump (none on mine)?

Ian McD

Another thought - it might be tricky to fill both grooves. The solder in the first one will probably run out when you heat the second one. Part full may be the best you can achieve. Might epoxy or JB Weld be easier? But you don't want anything that might debond in use.

Ian McD

You would probably be able to see if the oil grooves go right through if you take the mag sprocket off the inlet spindle......

I've used JB weld for all sorts of things and it's excellent but does need absolutely oil free conditions to stick properly.

The current NOC spares list shows the proper bush (C2/19) available - £16.85......

It does say in the Edgar Franks book that the oilway on the inlet cam bush is stopped off before the end, as also pointed out by Hans in his March 11th 2016 post. It could therefore be that you were supplied with the wrong bush, designed for the crankcase end, where the oilways pass right through. If so, it may be best to obtain the correct bush, rather than attempting to block off your existing one.

Ian

makes you wonder what would happen if you put a one way valve the same as the one used for the engine breather in place of the overflow pipe fitting in the timing cover. engine running, would it have the effect of pulling the oil back in through the inlet cam bush or equalizing pressure build up . i don't know. just a thought

Barry

I don't think that would work. That part of the timing case (the mag chain drive enclosure) is effectively open to atmosphere as the magneto does not seal to the large aperture in the back, so unlikely to be any significant pressure variation going on in there.

Possibly posted this before but I have seen this neatly engineered solution - see photo. The mag drive overflow pipe is routed into a non-return valve connected to a hollow engine bolt at the bottom of the crankcase. As the piston rises the oil escaping from the mag case is drawn back into the crankcase.

ian McD

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like i say Ian it was just a thought. thats a good idea shown in the photo.

Barry

I would be concerned about putting it at the bottom of the crankcase as that would normally be flooded with oil. But somewhere half way up may work well?

Nicely engineered job though.

It is a nice job, I was very impressed. The owner is a very competent engineer. The closest bolt on the Norton, and mid-way up the case, is also the bolt that holds the footrests. We might not want to take any strength out of that one! The next one down is near the bottom and might be below the oil level. Certainly it would be close to the pickup point for the return side of the pump.

Ian McD

I'd worry about the muck that might get into the mag chain housing and which could then contaminate the oil returning to the sump.