THREAD CORRODED/ DAMAGED AND CAN'T GET THE NUT OFF.
Rattle Gun.. you probably don't have one
Do all the usual's.. like clean the thread .. Plus Gas or WD40.. Plus Gas is better..
oil the thread .. if you don't have any get a few drips off the end of the dipstick..
STILL WON'T COME OFF .. TIME TO DECLARE WAR ON IT..
Nut Splitter.. About seven quid to buy.. if you can get it on.. doesn't always work.. can leave you with a bigger mess than you started with..
Heat.. Ordinary gas blowlamp will do .. be careful of rubber etc.... ball joint's, track rod ends etc.. often have a plastic nylon insert.. so may be ruined..
safety ..fire extinguisher/ bucket of water/something to beat out flames like next doors cat
Heat and Quench.. Same as above but chuck some cold water on it when hot.. thermal shock.
Hacksaw.. Chop off the damaged thread protruding from the nut and then wind the nut off.. the bolt thread inside the nut is usually OK ..
Hacksaw.. Just chop it off..
Angle grinder .. As above..
New Nut/ Die Nut..Wind a new nut, or better still a die nut.. onto the protruding damaged thread to fix the thread and then remove and wind the original nut off. use oil
Make a die nut.. Get a new nut. thread a junior hacksaw blade through it.. cut a slot along all the threads.. the slot will cut and clean damaged threads.. use oil.
Drill.. drill through side of nut flat.. drill a pilot hole in center of nut flat. use bigger drills until you have drilled the whole nut flat off. works like a nut splitter..
Mole Grips.. just use them..
THE BOLT ROTATES AS YOU TRY TO WIND THE NUT OFF .. BALL JOINTS ETC..
Ball Joint Splitter... Smack a ball joint splitter in there to seize the bolt and stop it turning..
Hacksaw /Angle Grinder.. cut a slot in end of bolt for screwdriver .. stop it turning.
Araldite.. Worked for me once .. glue the bolt and leave it overnight.. Got to be clean..
Mole grips.. Grab the end few millimeters of thread.. wind the nut down. when the nut is down to the grips move the grips to other side of nut.. wind the nut off past the now damaged end ..
Die Nut.. Run a New nut/Die nut up the thread before unwinding the original nut.. oil
Most of these are destructive so use common sense..
HOW TO STOP THEM FROM CORRODING IN THE FIRST PLACE..
I know.. you are only going to do the job once so why bother..
famous last words...
On exhausts use brass or stainless nuts . DO NOT use on suspension..brakes etc..
Put extra nut/nuts on to protect exposed thread. + coppaslip.. good on exhaust manifolds..
Italians like to use long bolts .. if you can use bolts that are the correct length about two threads protruding from nut. less to corrode..
Thread protectors .. kinda black rubber condom things that slide over the exposed thread to protect it. +coppaslip/grease.
Cable sheath will do..
not a lot of good on manifolds and exhausts..
You used be able to get some splodgy stuff called "Elastomer".. slop it on the thread with a paintbrush and it dries like a rubber sheath.
worked for the Navy and they know all about steel and salt water ..