1961 G3LS oil leak on return pipe fitting

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Joined: Tue Sep 24, 2019 4:22 pm
Location: Salop UK

1961 G3LS oil leak on return pipe fitting

Postby AyJayBee » Fri Jan 03, 2020 10:49 am

I am having problems getting an oil tight connection on the short copper return pipe which screws into the crankcase on my 61 G3LS. The crankcase has been welded and re threaded by Ken De Groome, made a good job, but I am unable to get a seal on the copper pipe. Any suggestIons - replacement pipe union? Sealant on the threaded part? Convert to 2 stroke? Obviously I am being careful not to damage the new boss on the crankcase, but perhaps I am not getting it tight enough. Any advice re fitting or source of replacement copper pipe would be appreciated.
Thanks, Tony
Last edited by AyJayBee on Sat Jan 04, 2020 3:48 pm, edited 1 time in total.

Posts: 2011
Joined: Mon Mar 24, 2014 5:44 pm
Location: Aberdeenshire

Re: G3LS oil leak

Postby Mick D » Fri Jan 03, 2020 4:04 pm


The only place the leak can originate from is the taper between the crank case and the oil pipe olive - have a look at both for damage burrs etc.

Regards Mick

Posts: 100
Joined: Mon Oct 02, 2017 7:27 pm
Location: Seattle area, WA USA

Re: G3LS oil leak

Postby Dixter » Sat Jan 04, 2020 4:54 am

Hi Tony, a couple of possibilities. As Mick pointed out, the leak originates at the male flared face of the copper pipe. You can try a commercial refrigeration repair shop, or a well stocked hardware store and buy a flared copper seal. They are supplied “dead soft” to aid crushing and sealing as the joint is tightened. These cost pennies.

Installing the flared copper seal is aided by a smear of wheel bearing grease on the male pipe face acting like glue to hold the seal in alignment during assembly.

Alternatively, buy a small tube of Loctite 567 anaerobic plumbing sealing paste and apply to the flared face, carefully following Loctite’s direction. Precisely! Amazon sells the Loctite product. A tube will cost $8 USD, and a tube will solve many problems and last years. I favor the Loctite solution.

Do not over tighten the threaded union.

Ciao, DC

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