Oil leaks - quick Q

Information relating to the Matchless G9 or AJS Model 20 500cc twin
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Oil leaks - quick Q

Postby Oggers » Thu Jun 11, 2020 8:22 pm

Chaps

Still not absolutely certain my leaks are not coming from the crankcase join just above the filter housing. As a thought, would pressure be reduced in the housing by removing the felt filter? A short test run after cleaning the area, running with no filter, and then checking for drips may prove something......I am thinking there must be quite a bit of pressure in there, which may be finding its way through the crankcase halves join - especially if PO has omitted any gasket.

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Re: Oil leaks - quick Q

Postby Oggers » Sat Jun 13, 2020 3:59 pm

.....and to add, another potential oil leak path just discovered. A thorough check revealed that on removing the dyanamo retaining strap away from the top threaded bar upon which a nut tightens that same strap over the dynamo, that the tapped hole for that bar is weeping oil. Not much, but definitely something there. On removing the small length of threaded bar/screw call it what you will, that the tapped hole is NOT blind! It seems that there is an open passage to the crankcase. as evidenced by me poking a wire right through it!

This bike seems to be a veritable booby trap for anyone seeking an oil free lifestyle! So, thread tape and a plug of RTV mastic seems to be in order....We'll try again....

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Re: Oil leaks - quick Q

Postby Mick D » Sat Jun 13, 2020 4:07 pm

Oggers wrote:So, thread tape and a plug of RTV mastic seems to be in order.


Hi

I've got into the habit of dipping all threads into Wellseal before I assemble them - the theory being it will stop oil wicking along the threads and when 'cured' it affords some resistance to the thread unscrewing due to vibration should it lose torque.

Guess you could do similar with silcone, (RTV), but I avoid it for fear of excess entering the oil system.

Regards Mick

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Re: Oil leaks - quick Q

Postby Oggers » Sat Jun 13, 2020 7:51 pm

Mick

I can tell you I have got into the habit of using Wellseal, RTV, Hylomar, thread tape, weld, solder, gasket compound, and Belzona on each and every joint. In fact, I seriously doubt whether this bike will ever be oil tight until it is completely encased in resin - and even then the blasted thing will leak somewhere.... :headbang:

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Re: Oil leaks - quick Q

Postby clive » Sun Jun 14, 2020 8:25 am

I certainly would not use a plug of RTV if it is not a blind hole. Too much risk of the plug getting sucked into the crankcase. Concentrate on sealing the threads.
clive
if it ain't broke don't fix

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Re: Oil leaks - quick Q

Postby Oggers » Mon Jun 15, 2020 7:52 am

Clive - there is a risk perhaps but surely mitigated by the fact that the crankcase is at positive pressure when the bike is running?

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Re: Oil leaks - quick Q

Postby Mick D » Mon Jun 15, 2020 8:21 am

Oggers wrote: the fact that the crankcase is at positive pressure when the bike is running


Not so sure about that :? :?

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Re: Oil leaks - quick Q

Postby Andy51 » Mon Jun 15, 2020 7:34 pm

I understood that the point of the breather is to create negative pressure in the crankcase, to reduce resistance as the piston descends, and to reduce oil leaks. Andy

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