Author Topic: Re: 55 Matchless G9 Dynamo exterior cork gasket  (Read 1191 times)

Offline Oggers

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Re: 55 Matchless G9 Dynamo exterior cork gasket
« on: May 26, 2019, 12:02:22 PM »
Chaps

Noticed quite an oil leak coming from the dynamo and the timing cover mating faces. The gasket is of an annular type and of thick cork, and although seemingly not too bad, I have ordered replacements. The sealing seems to be done on the inner edge of the cork gasket and the dynamo "stub" end, and perhaps the vertical face of the dynamo - where there is no gasket.

Possible solutions - O ring instead of cork gasket?
Make up thin gasket for the vertical face?
Apply blue Hylomar or similar - in addition to the above.

Thoughts welcome.

Must admit I still have not looked at the crankcase breather valve  - on the crankshaft on the other side - as it it under the pressed steel primary chaincase and I don't really want to disturb it. I understand  pressure may be build up in the timing cover and blow things if this valve is u/s   

Offline R

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Re: 55 Matchless G9 Dynamo exterior cork gasket
« Reply #1 on: May 27, 2019, 12:16:08 AM »
Not much use 'fixing' or improving the gasket if excessive pressure is simply going to blow it again, is there ?

Some of those breathers you can blow into and see what is what, not knowing the matchy one specifically.
Is it the disk flapper valve in the hollow crank output shaft. ?

Can you take off a tappet cover, say, and see if it is breathing excessively.
Of couse, if the rings are worn or stuck and blowby is the problem, then the problems are deeper...
Aren't old bikes fun !

There are some very knowledgeable folks on the Jampot Forum and Yahoo Matchy chatgroup.
« Last Edit: May 27, 2019, 12:18:03 AM by R »

Offline Oggers

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Re: 55 Matchless G9 Dynamo exterior cork gasket
« Reply #2 on: May 27, 2019, 09:13:33 AM »
Not much use 'fixing' or improving the gasket if excessive pressure is simply going to blow it again, is there ?

Some of those breathers you can blow into and see what is what, not knowing the matchy one specifically.
Is it the disk flapper valve in the hollow crank output shaft. ?

Can you take off a tappet cover, say, and see if it is breathing excessively.
Of couse, if the rings are worn or stuck and blowby is the problem, then the problems are deeper...
Aren't old bikes fun !

There are some very knowledgeable folks on the Jampot Forum and Yahoo Matchy chatgroup.

No it isn't, but then again I don't know for sure at present whether is is excess presure or a duff joint. I believe the breather is a disc in the crankshaft - on the nearside, and it will be my next port of call if the joint fails again.

I also have to consider the bike is newly rebuilt. That may have some bearing on the matter.