Author Topic: Cannot stop oil coming out of dynamo interface with timing case  (Read 4185 times)

Offline Roadrocket649

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Hi Guys

I wonder if you can help

Bike : BSA A10 Super Rocket
Year:  1958

I have oil coming out of dynamo interface with timing case which ends up covering my foot and silencer

I have re-set the dynamo, tightening the holding bolt till it is gripping the dynamo, and then tapping with a hide hammer to ensure it is pressed firmly against the Timing case
-   No Joy
I sealed the inside of the housing interface with the dynamo with loctite 5910 sealant, and tried again
-   No joy
A friend advised that there should be a cork seal (67-708) between the dynamo driving sprocket and the casing, to stop oil leaking out of the bearing
(I see no mention of this cork seal in the Haynes Manual I have (maybe I have missed it ? but it is in the Draganfly Catalogue)

Is this correct?

As that would mean tightening the Dynamo driving sprocket (which is turning)against the cork seal which in turn will be pressed against the casting (which is static) holding the bearing through which the drive sprocket shaft is retained

Surely the cork seal will just disintegrate

Could anyone help please

Offline A10Boy

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I would investigate how the oil is getting into the dynamo chain chest as its not supposed to be there, the chain runs in grease not oil. Could be that the outer cover gasket was damaged during assembly allowing oil in. The cork gasket goes between the dynamo face and the inner timing cover to stop grease leaking. There is no seal under the dynamo drive sprocket.
HTH
Regards

Andy

1958 Super Rocket
Plus
1974 Kawasaki Z1a
Yam XJR 1300

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G'day roadrocket469,
                             The bush in the inner cover that the shaft goes through should have a scroll in it to direct oil back into the motor. Does yours have this scroll? Never had much luck with those cork or felt seals, get eaten very quickly. Neither of my A's have one and never have more than a teaspoon of oil in the dynamo chest.
As A10Boy suggests the gasket could be the culprit as well.
Low melting point grease for the chain, a little oil wont hurt if the dynamo is sealed well.
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline Roadrocket649

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Hi Guys

Muskrat: Don't know about the scroll - a toolmaker in the BSA Owners Club assembled that part of the motor, and he is on holiday so I cannot find out

A10Boy: I have used a normal gasket with loctite 5910, and then just Loctite 5910 - no change - assembled three times with same result - oil leakage

Certainly there is no mention in the Haynes manual of a cork seal, but in the BSA Draganfly catalogue it mentions the cork seal 67-708 as an Idler Pinion Oil seal.

I used grease in the dynamo drive sprocket compartment, and had agrease / oil combination dripping out

I, like yourselves cannot see where it is coming from, as there appears to be sealant on the oil pump/ dynamo drive sprocket interface

I am wondering that, as there are signs of the chain having fouled or jamed the lower side of the  compartment, whether this has bent the lower end of the compartment down, so oil from the oil pump area can access the compartment

Is the oil pump area full of oil for the pump to pump, or is this just residual seeping out of the pump?

The pump has brand new parts ex SRM

Offline Topdad

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HI ,there defo a cork washer on the end of the dynamo where it butts to the crankcase and as this is one of the very few places that I've never experianced any oil leaking from on my A10's I would think you have a damaged /warped timing case ,try it on a piece of glass ans see if it sits level or proud ,some previous owner could have overtightened it on one side and actually bent the case, I've seen 'em really out of line, hope that helps best wishes Bob 
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Offline rocker21

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there are several possible causes for this, first oil should not be in the dynamo compartment that should be running in grease only, yes there should be a cork gasket on the dynamo but normally it does not need any sealing compound. assuming the inner and outer timing cases are flat and mate correctly and have a decent gasket there is only one way oil can get in and that is via the drive shaft, this can be down to a worn shaft or bush, the bush should have a grove that keeps the oil in the engine area and out of the dynamo, but sometimes i have seen a lot of end float on the shaft which does not help as the only thing that controls that is the thrust face on the bush in the timing case and the one in the crankcase, in the past i have removed this bush and fitted a needle roller bearing which makes this a real problem and then had to modify the inner timing case to take an oil seal which fixed it .

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With both covers off the motor mate them together and have a look from the inside to check for misalignment (damage). Remove the sprocket (with a suitable puller or place cover on blocks of wood and give the shaft a sharp tap with a brass dolly  *eek*) and idler pinion shaft from the inner cover to check for scroll in the bush. Check the shaft in the bush for fit (easy spin, no wobble). If all that checks out OK buggered if I know. Like I said if the scroll is working there should be no or very little oil in there even without the seal.
Take care with the timing marks on assembly.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline wilko

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Remember it's a reverse scroll. Maybe somebody got it the wrong way in the past. They are quite effective so i would be investigating this.Lots of different makers  use this system with no problems, but i have heard of people getting the scroll in the wrong direction, which would pump it out.

Online bsa-bill

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Quote
but i have heard of people getting the scroll in the wrong direction
*red*,ah that would be me then Wilko.

There is a cork seal in the gasket set for behind the dynamo sprocket, can't think where else it would be for, and of course a big cork washer sits between the dynamo and the inner case
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline alanp

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There is a cork seal in the gasket set for behind the dynamo sprocket, can't think where else it would be for, and of course a big cork washer sits between the dynamo and the inner case
I find that the cork seal and the felt disintegrate so run without either and precious little oil gets in that chamber. Guess my scroll must be correct. Can't say I've ever noticed it though. The next time I have the misfortune to take area apart I'll look. The gap the seals have to fit will vary though with different part machining, expecially the sensitive taper so, sod's law, it's likely any seal will either be too loose or get squashed.
Alan
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Offline Roadrocket649

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Thanks Guys

Much Appreciated for all your thoughts

Roadrocket649

Offline A10Boy

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One other thing, check your crankcase breather is working correctly.

One more other thing, does it wet sump? Could be that this is where the over pressure is forcing oil out, does it leak for 10 mins then stop or does it leak all the time? Check oil tank level before and after running, if the level was right after a run, but is low before start up, dont fill it until you have run the engine for 10 minutes. My a10 hasn't got a seal behind the dynamo drive sprocket and it doesn't fill the chaincase with oil. I dont believe there should be one there anyway.
Regards

Andy

1958 Super Rocket
Plus
1974 Kawasaki Z1a
Yam XJR 1300

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Quote
I dont believe there should be one there anyway.

Best panto voice "Oh yes there is"

it's part no 67-0708

[quote ]it's likely any seal will either be too loose or get squashed.[/quote]

Well wether it's needed or not is debatable but BSA thought it should be there and yes it will get squashed a little and once squashed will be a better fit, all the ones I've had were squashed certainly but only one ever broke up and that one was supplied for a belt drive kit but not I hasten to add by SRM or any other firms that make them, as a matter of fact SRM supplied a replacement that has not broken up.
One reason they might break up would be dependant perhaps on just where about on the idler shaft the idler gear is,it is key on but is only a tight fit, if for example the taper or sprocket taper was worn excessive torque on the dynamo sprocket nut to pull it onto the taper could pull the shaft through the gear and leave too much room for the cork washer, OTOH if the gear was not far enough through the shaft it might be that the opposite was the case and the washer got really squashed to much before the taper was tight.

Not sure if that reads just the same as it sounds in my head lads, hopefully you understand what I mean.
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

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I know what you mean Bill. i always use the hot gear/frozen shaft method and loctite, making sure it's in the right spot.
Andy might have a point re wet sumping.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline Hubie

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G'day,

I'm far from the foremost expert here but has anyone mentioned the cork seal behind the large sprocket that sits up against the case?  That one I know must be there.

Cheers,
Hubie.
1959 BSA Golden Flash
1956 Royal Enfield Super Meteor
1955 Royal Enfield 350 Bullet
2007 Harley Davidson Sportster 1200 Custom

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