Oil leak in vicinity of dynamo/crankcase

Information relating to the Matchless G9 or AJS Model 20 500cc twin
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Re: Oil leak in vicinity of dynamo/crankcase

Postby Oggers » Mon Dec 02, 2019 2:40 pm

Clive

I tried that method first of all. What I found was that once on the dynamo, the cork gasket was incredibly difficult to locate into the timing cover recess. Essentially, the gasket outer circumference was slightly greater than that of the recess, and distorted further by the slight distortion of the circularity - is that a word? - by the deformity caused at the drawbolt. I found that due to the dynamo proper, and the need to locate the drawbolt, I also couldn't prise the gasket into the recess.

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Re: Oil leak in vicinity of dynamo/crankcase

Postby MalcW » Mon Dec 02, 2019 3:29 pm

I've just been out to check on my 650. As I thought, the cork gasket doesn't go into the timing chest recess, but is pressed up against it.

Malc

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Re: Oil leak in vicinity of dynamo/crankcase

Postby ajsph » Mon Dec 02, 2019 4:45 pm

The cork gasket must fit into the recess. I mounted the Dynamo on my 1956 model 30 for 20 years and 43000 km.ago, and it has been leakfree since it was mounted.When I mounted the dynamo first time oil was seeping out on the underside of the dynamo, I found that it was because the oil was seeping between the shaft and the spacer that sits between the gear wheel and bearing, I applied a thin layer of RTV silicone to the shaft, and a thin layer of aquarium silicone glue on the outside of the cork gasket, it has been leakfree in since it was fitted.
regards Poul
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Re: Oil leak in vicinity of dynamo/crankcase

Postby clive » Mon Dec 02, 2019 11:14 pm

Oggers wrote:Clive

I tried that method first of all. What I found was that once on the dynamo, the cork gasket was incredibly difficult to locate into the timing cover recess. Essentially, the gasket outer circumference was slightly greater than that of the recess, and distorted further by the slight distortion of the circularity - is that a word? - by the deformity caused at the drawbolt. I found that due to the dynamo proper, and the need to locate the drawbolt, I also couldn't prise the gasket into the recess.


I wonder if the cork gasket is the right size then. I agree the stud causes disruption to the circularity but in my case it all fitted easily.
clive
if it ain't broke don't fix

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Re: Oil leak in vicinity of dynamo/crankcase

Postby Oggers » Tue Dec 03, 2019 8:43 am

Clive

Quirte correct. I did wonder that myself as the gasket was somewhat loose on the dynamo. All 3 - now used - came from our noble club spares.....

Where do you believe the leak path is likely to be at the interface? Inner or outer edges or mating faces? If the latter you may stand a chance with cork, if the former - not so sure.

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Re: Oil leak in vicinity of dynamo/crankcase

Postby Samuel » Tue Dec 03, 2019 9:04 am

I too found the Club spares cork gasket to be too large and reverted to the old one suitably cleaned up when I was refitting dynamo to my now ex G9.
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Re: Oil leak in vicinity of dynamo/crankcase

Postby clive » Tue Dec 03, 2019 10:20 am

Sam, If you ever decide to ex my ex G80 give me first refusal!!!!!!
clive
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