What I would do, but not accepting any responsibility if anything goes wrong should you or anyone else decide to do the same! Assuming I’d already put lots of releasing oil (plus gas not just standard wd40) on it and it wont turn with molegrips the only option before drilling it out is to carefully put a good amount of heat into it. An induction heating coil would be best and safest for all the obvious reasons, but as I haven’t got one and my local HSS etc don't have one in stock (though they can get one in in a few days). I’d wait and do that, but if I need to do it now its a blow lamp job. I’d make sure to do it outdoors and be very very very carefully not to accidentally scorch anything else. First though I’d take the tank off (again its obvious why) and apply the heat from above until its cherry red then get hold with decent pair of molegrips and try it. If it wont I wouldn’t force it - I’d poor cold water ONLY ON THE STUD and try. If it wont then more plus gas, wait and then try. If it still won't then I’d heat it up again etc etc and keep on repeating the cycle until it came out, but I wouldn’t apply a lot of force as I know patience is a virtue and rushing it will just knacker up the hole. That’s what I’d do, but as I stated at the opening - I cant be held responsible in any way should anyone decide to try this method!
Yep been there next time warm the engine up then crack the nuts a turn , a bit to late for that now . Good luck
the studs are a really crap design. why they dont fit them with brass nuts ill never know. im hoping to get a nut welded on the protruding part and hopefully ease it out that way. im on no rush....
Try and file a couple of flat edges on it to get a better grip with mole grips if the welded nut fails, I once used a impact drill in reverse on something similar, just tightened the drill Chuck on it
I would not try to weld a nut on as it does not look like you have enough sticking out. I would just try heat and plenty of it
If the heating and vice grip method mentioned above doesn’t work, I’ve welded a nut onto a broken stud many times with good success. If you haven’t done already, apply a good dose of penitrating oil and let it soak in. Get a nut big enough to fit over the stud and give it a good weld at the centre, immediately loosen it gently while it’s still hot as the heat from the weld will penitrate and help free it. You will obviously have to take precautions not to cause any damage to the surrounding area with sparks and heat, only attempt if you’re confident.
following on with this issue do i replace with steel studs and copper nuts to avaoid the same issue in the future ?
I generally tig weld nuts to the studs, then wait till it stops glowing then most of the time they will come out