Oil leak at the head?

Towner said:

Constant,
do you think that nearly all of the leaks at this nuts are caused by these cracks ? I had the problem at mine too and in the end I cured it by the XS 650 valve. A good solution and much cheaper than a new head.
Regars,
Ralf

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Ralf,

Leakage at that particular spot can be caused either by oil from the pushrod tunnel finding its way up via the threads of the 5/16" studs or by crack(s) as mentioned in my earlier comment. During pressure testing I have seen heads with a crack behind one or behind both 5/16" nuts. If the crack is still very small (it is likely the crack will get worse in time) then you might indeed cure the problem with a (reed type) engine breather valve as the valve will reduce engine pressure.

Regards,

Constant Trossèl
www.hollandnortonworks.eu

N0rt0nelectr@ said:

Started it yesterday and no leak! Hot damn, for the first time in weeks I feel like I'm not fighting a loosing battle.

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So the leak probably wasn't caused by a crack. Nevertheless it shows how intractable a leak between pushrod tunnel and stud can be.