Classic Knackered Exhaust Bolts

probably not as bad as they look. first, you could heat-cycle them a few times (if engine runs*?) by getting studs nice and hot and then dousing with the penetrating fluid of your choice, allow to cool and repeat. *A blowtorch will do the same if not. Then a really good fitting full-hex socket at the ready for seeing if they will undo, again, when fully hot.



I did same engine recently (have 3) and used these:-
https://www.ebay.co.uk/itm/Ford-M8-...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

 

For these sort of jobs I use a junior hacksaw, or sometimes if access is it gives better access a dremel with a cut-off disc. Cut a slot in the nut parallel to the stud and so that it is just touching the threads. Once you have cut that slice off use a chisel against the cut edge to knock the remaining nut in an unscrewing direction. This should open it up enough to let go of the stud and come off.

 

worth doing if all else fails ^ but you can still make out the hex, and even if it's a delaminated hex, it can still be enough to undo provided a tight fitting full-hex socket is used, Have had lots of success like this, on very similar looking studs.

 

The studs are screwed into the cylinder head, M8 if I remember. The nuts have a very small hex at 10mm so they round off very easily when they get corroded. I was going to replace the ones on my own Classic with stainless but the standard sized nuts won't fit. There's just not enough space.

 

Penetrating oil (Super Crack Ultra is good) soaked in over a couple of days. Then a bit of heat (until nut is glowing is good but don't melt anything) and tighten each nut slightly before backing them off with a single hex socket of good quality as mentioned by @Chris

Take it steady and err on the side of caution. If you're not confident then get your local bike shop to do it. They don't look too bad but I would say keep the replacements cleaner.

Good luck.

 

Repeated cycles of heating with a hot air gun, and quenching with penetrating oil, then using a bolt grip tool slowly and smoothly reliably gives the right result.

 

Congratulations. Bloody awful job. Andy

 

O.P. hasn't done his yet Andy!

is there an echo in here/ - definitely writing in that invisible ink again,, not sure why I fucking bother

 

Doh ! Where’s a face palm when you need one. Andy

 

If you can get hold of some PB Blaster release oil, give them a soak overnight.
Then give them a good heat up with a blowtorch, get them near red hot.
Leave to cool and try a full hex socket. If you can get one in a nut splitter will open up the thread.
You will probably need to run a die nut down the thread on the stud to clean up the thread.
If replacing the studs, recommended, don’t use stainless steel.
Use molybdenum disulphide on the threads.

 

Following the advice given so far, I would extend the application of heat and penetrating fluid all the way along the stud to the cylinder head, because given the state of the studs, it may be preferable that the stud gives first and undoes with the nut. I'd be quite happy for the nut to undo the stud as it will halve the work, rather than remove the nut and then have to remove the stud.

 

I knew you'd ask! memory shot - I even looked in my "purchased" list but of course they don't record what length you picked. Then I thought, well you'll just measure yours.. there's plenty of room so no harm in going longer. Have you had any luck removing yours?

 

The studs are stuck so the exhaust headers are on and the engine is in the frame, so angle / space on the rear head is limited even to get a ring spanner or socket on and turn it more than a few degrees. I think using anything more substantial like a nut splitter is not going to be possible.
I would not aim for red hot, as the heat soak from the cylinder is so strong that you are putting an awful lot of energy into it in a very uneven way compared to normal running. I heated the end of the stud and the nut hot enough to just vapourise the penetrating fluid when sprayed onto the stud to cylinder area as you are aiming to remove the stud from the head, and cooling the stud with pen fluid helps the process of getting it to travel up the thread, as well as breaking any corrosion or old loctite bond.

 

I just did this on my Monster. The nuts weren’t quite as bad but they came off dead easy after a squirt of Plus Gas (thanks @CRYSTALJOHN !).
Have you actually tried to remove yours yet?

 

The front exhaust nuts on my Monster 695 are in similarly corroded condition, I keep putting the job off until I'm in the mind.!

 

Don’t use bolts or threaded rod. Get proper length studs with an unthreaded section.