Snapped Exhaust Studs

[shammon]

Hi, Yet again finding the prob of snapped exhaust studs on my xj600s 1993 project , Can any one tell me the size and pitch of the exhaust studs that go in to the engine block? and suggest what size of heli coil to replace them with as there all going to be drilled out as snapped of clean (4 of them that is).

Thanks

[HRHpenfold]

the original is M8x1.25mm into the block

I drilled out the thread starting at 3mm and then going up to the tapping size at 6.5mm, then picking out the thread that was left and using a new stud, actually I cut down a bolt to fit, though the original has a standard size into the block, it is metric fine for the nut.

you would only need to helicoil it if you drill off centre, in which case you get the drill and tap for the helicoil in the kit,


Did you heat the old studs to a dull red before unscrewing?
as they are high temp loctited?

[shammon]

Thanks for that info. I did heat them but they were so badly rusted as well as several bent turning them they just sheared.
Im trying not to have to remove the engine to get better access but will try it and post up a few pics.

[CD]

Dont waste your time trying to avoid taking the engine out.

If you drill off-centre the threads WILL need helicoils. But with the frame in the way, they will be nearly impossible to drill straight and then the headers wont fit.

[shammon]

Hi. Ive had a fair bit of experience with pre divvy snapped nuts and same on thunderace. Ive now got all the special tools required to do this without removing the engine. il post up pics and a short video shortly here. Thanks.

[shammon]

Finally had time today to start it, and no need to remove the engine all thanks to drill add on attachments, made a short clip to show what i used.

[neilmud Lord Protector]

Great vids but show us the full fing not just the edited highlights I know it takes more than just a couple of minutes to do these jobs. you make it look too easy

Neil

[shammon]

Hi, When im next in the garage il get the HD cam and go through what I did exactly from start to finish. Ive one let to do so will be able to show that.
Cheers Il post up asap poss next weekend Il post it here first.

[CD]

The even easier way with a snapped stud like that in the picture is to weld on a washer onto the broken stud and then a nut onto the washer. The intense heat of molten steel breaks the seizure and the old snapped stud can be simply unscrewed.

If any header nuts are seized DONT try to force them. Fire up the cheapo Aldi welder and arc some weld onto the old nut. It will then unscrew easily. If the stud threads are chewed/corroded/etc use a proper tool as in the video. You could also weld onto the stud and unscrew it with locked together nuts.

You don't need to be able to weld and a cheap Aldi welder will be more than enough to get the steel stud bright red hot. It will then unscrew. For welding washers & nuts onto broken studs you do need to be reasonably good at welding.

When arc welding ALWAYS disconnect the alternator, sparks control box and battery. This avoid stray currents duffing-up your expensive electrics. Also protect nearby aluminium and frame from arc spatters. Wet cotton dust sheets work fine.

If welding the nut/stud doesn't work you can still drill the broken stud. The long drill holder makes it easier to get it aligned, but it's a skilled job and it's all too easy to damage the tapped threads in the cylinder head.

When done, use stainless dome nuts and copaslip.