1957 350cc Red Hunter

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JohnHyslop
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1957 350cc Red Hunter

Postby JohnHyslop » Fri Dec 13, 2019 8:29 pm

Hi
Looking for some advice and possibly part to fix.
My Red Hunter has developed an oil leak which looks like its coming from the rear of the cylinder head gasket, I’ve not tried tightening the head just in case it makes it worse, the leak is not bad but is blowing oil onto dynamo which I’m not sure is a good thing.
Any advice would be appreciated, if it is the head gasket could I re- anneal it by heating, as has been suggested in the oven?

will_curry
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Re: 1957 350cc Red Hunter

Postby will_curry » Fri Dec 13, 2019 9:07 pm

As far as I remember there isn't a head gasket on these engines. The combustion is sealed
in by grinding the head onto a lip on the top of the barrel and the oil is retained with two rubber seals,
one for each pushrod tube. These are one likely cause of oil on the dynamo if it isn't coming
out of the rocker box gaskets. The other place for oil to escape is via the two sleeve nuts, one
in each rocker box.The sleeve nuts don't need to be dead tight - as the alloy head warms up and expands
they'll get tighter. Too tight and there is a risk of damage to the head.

Somewhere on this forum is a thread detailing how to replace the pushrod seals with a spacer and
two 'O' rings. Much more satisfactory.

Simon.Gardiner
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Re: 1957 350cc Red Hunter

Postby Simon.Gardiner » Sat Dec 14, 2019 12:35 am

Wot Will said, John!
There's no harm in checking the head bolts (and rocker boxes) 'just in case' but it's quite likely to be the push rod seals - in my experience modern ones often don't last long in service (Drags now even advise cutting their new ones down slightly, if left 'full height' they start to distort and collapse).

SG
'55 Huntmaster, '56 VH, ' 51 VH, '80 R100RT, '00 Sprint ST (but all those Ariel parts can only make one running bike...)

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adrie.degraaff
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Re: 1957 350cc Red Hunter

Postby adrie.degraaff » Sat Dec 14, 2019 8:00 am

There are heads where the ridge of the barrel is lower than the gab in the head and there for leaking, a brass-copper washer will solve that but need higher rubber tubes aswell.

JohnHyslop
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Re: 1957 350cc Red Hunter

Postby JohnHyslop » Sat Dec 14, 2019 5:00 pm

Thanks men will have a really good look, know rockers are fine so it’s possibly seals, might try pinching head down a little first,
as it’s head off if leak persists, thing is bike running really well at moment and it feels wrong to play with it when it’s going so good.


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