27 replies to this topic

[dklawson]

There is a lot of good advice above.

My personal method combines several of the suggestions given by others.
Drain the cooling system.
Heat what is left of the stud with a propane torch.
Remove the flame and quench the stud using penetrating oil. Flood the area where the stud goes into the head.
Strike the top of the stud with a hammer... just like the stud was a nail.
Repeat this sequence at least a half dozen times. Expect the penetrating oil to burst into flames... so wipe the excess off before re-applications of the flame.

Finally use your vise (mole) grips to grab the stud.
Apply more oil at the stud/head interface.
Wiggle the stud back and forth at first. Apply more torque to turn the stud "IN" than out.
Once the stud starts the slightest bit of movement, apply fresh penetrating oil and continue wiggling the stud back and forth in short, increasing arcs.
You do not want to immediately start backing the stud out. Turn it in and out to work the oil down the threads.
Eventually it will be obvious that you can back the stud out completely.

When refitting the thermostat, you can use stainless steel bolts of the correct length, or stainless studs. If you choose to use OEM type steel studs, put anti-seize compound on the entrance to the tapped holes and on the male threads of the studs. Also apply a bit of anti-seize up the shanks of the studs to prevent the studs from seizing to the holes in the thermostat housing casting.

[Trick77]

My method is. a lot of wd40 then file down the top of the bolt on two sides so they are flat rather than round. then mole grips and possibly breaker bar on the end and wiggle it loads back and forward till it comes off. I dont think heat is the answer on a cast iron block but i could be wrong.

[dklawson]

You are not heating the casting, you heat the stud. The quenching of the stud when hot helps wick the oil down into the threads. Again... not heating the casting.

[robbie-woods]

There is a lot of good advice above.

My personal method combines several of the suggestions given by others.
Drain the cooling system.
Heat what is left of the stud with a propane torch.
Remove the flame and quench the stud using penetrating oil. Flood the area where the stud goes into the head.
Strike the top of the stud with a hammer... just like the stud was a nail.
Repeat this sequence at least a half dozen times. Expect the penetrating oil to burst into flames... so wipe the excess off before re-applications of the flame.

Finally use your vise (mole) grips to grab the stud.
Apply more oil at the stud/head interface.
Wiggle the stud back and forth at first. Apply more torque to turn the stud "IN" than out.
Once the stud starts the slightest bit of movement, apply fresh penetrating oil and continue wiggling the stud back and forth in short, increasing arcs.
You do not want to immediately start backing the stud out. Turn it in and out to work the oil down the threads.
Eventually it will be obvious that you can back the stud out completely.

When refitting the thermostat, you can use stainless steel bolts of the correct length, or stainless studs. If you choose to use OEM type steel studs, put anti-seize compound on the entrance to the tapped holes and on the male threads of the studs. Also apply a bit of anti-seize up the shanks of the studs to prevent the studs from seizing to the holes in the thermostat housing casting.

thank you sooooo much that is the best advise i could have asked for!!! going to try it on saturday dont care if it takes all weekend just want the bloody thing out without any more damage! thanks again

[robbie-woods]

after i have heated up the bolt do i let it cool down before i try and undo it or try to while its still hot?

[lapider]

while its still hot

[robbie-woods]

thank you

[charliedurrant]

While it's hot! Trust your strength, if you think that you are putting in too much effort with whatever you are going ot use then it is probably too much and the stud will snap. Heat and WD40 again..... then try again. Take your time, have a G&T or another sutable drink and it will come out. I've got to do the same with two thermostat studs this weekend and I hope I don't break them as giving advice is easy!

Charlie

[bmcecosse]

Hair dryer will never do it - get a gas blow torch on the stud - get it RED, then let it cool.... use stillsons on the stud. When refitting, run a drill bit through the thermostat housing holes to open them up slightly - and smear the studs with grease - copper grease if you have any.

[charliedurrant]

Stillsons will work but the only issue is that the force applied is not uniform so be careful. I tend to get carried away and annoyed with stuck studs so be careful with the amount of force and direction the force is applied to the stud.

[robbie-woods]

okay guys got the bolt out last night, all went fine got some advice off my next door neighbor who is a mechanic he said to try and do it up a tiny bit before trying to undo it and that worked a treat!! came right out with no problems after that! no heat was needed but still plenty of wd40!

[stuwhitfield]

I've found plus gas not wd40, the double nut method and welding/ quenching the best way. Make sure you copper grease it before reassembly to avoid this in the future!

[dklawson]

Not trying to "toot my own horn", but I also said to turn the stud in and out in small arcs, starting with more torque "in" than out. The idea is to break it free and work the oil down along the threads before trying to unscrews the stud.