glueguy (Forum Supporter)
glueguy (Forum Supporter) GRM+ Memberand Dork
12/10/23 4:27 p.m.

Engine is now out of the car.  Threads are gone but the stud is still secure and whole.  No experience here - what guidance do y'all have for me?  $2000 car so recovery is better than spending money.  Before I cut the nut off there was a screwdriver blade worth of gap over the top of the nut at the exhaust flange, so there would be a couple of threads to still tighten against the header if I can just run a die on this.

Stampie
Stampie GRM+ Memberand MegaDork
12/10/23 4:34 p.m.

Weld a nut to it. Hope the heat helps break it loose. 

pilotbraden
pilotbraden UberDork
12/10/23 5:22 p.m.
Stampie said:

Weld a nut to it. Hope the heat helps break it loose. 

Yup. Also try heating it very hot and put candle wax on it before welding a nut on it. I believe that worked for Drboost

Brotus7
Brotus7 Dork
12/10/23 6:15 p.m.

MAP torch to the flange until it has a dull glow, then vise grip the stud out. Could try welding a nut on it first if you have the means. 

WillG80
WillG80 GRM+ Memberand HalfDork
12/10/23 9:26 p.m.
Brotus7 said:

MAP torch to the flange until it has a dull glow, then vise grip the stud out. Could try welding a nut on it first if you have the means. 

This. If you have an oxy torch, heat the manifold till it's red hot then move the stud back and forth with vice grips and it should break loose. 

porschenut
porschenut HalfDork
12/11/23 8:31 a.m.

Heat, vibration and thread penetrant.  Your choice of combinations.  The only fixed rule it don't snap the stud, you can see and feel the difference between metal yielding and threads unthreading.

stuart in mn
stuart in mn MegaDork
12/11/23 8:53 a.m.

If there's room, a redneck fix would be to use an old pair of vise-grips to clamp the manifold and exhaust pipe flanges together. 

David S. Wallens
David S. Wallens Editorial Director
12/11/23 10:52 p.m.

Maybe this piece from the archives will help: How to free rusty fasteners with a blow torch

Stampie
Stampie GRM+ Memberand MegaDork
12/11/23 11:33 p.m.

Looking at that again could you double nut where you still have thread and with a combination of heat back the stud out?  That leaves welding out of it. 

No Time
No Time UltraDork
12/11/23 11:56 p.m.
stuart in mn said:

If there's room, a redneck fix would be to use an old pair of vise-grips to clamp the manifold and exhaust pipe flanges together. 

Recently did this when the stud connecting the intermediate pipe to the cat finally failed on my nephews car. It wasn't a permanent fix, but got him home and to the shop that was able to make the permanent fix sooner than I could. 

On the original topic, I agree with heating the manifold. I would probably heat cycle it 2-3 times before trying to move it with a liberal dose of PB blaster while still toasty. 

If nothing else works, the ultimate hack is to cut a slot in the manifold from the edge of the flange to the stud parallel with the stud, heat the flange and then turn the stud out. This will let the flange open more when heated, but may not even require heat depending on the residual stress relieved by the cut.

You will want to use a through bolt if you go this extreme instead of a stud. 
 

dean1484
dean1484 GRM+ Memberand MegaDork
12/12/23 12:54 a.m.

Heat the  flange until it is red. Vice grip out the stud.  By heating the flang and not direct heat to the stud the hope is the flange expands more than the stud making the threaded hole fractions of an inch bigger freeing the stud. 

preach
preach GRM+ Memberand UltraDork
12/12/23 7:27 a.m.
pilotbraden said:
Stampie said:

Weld a nut to it. Hope the heat helps break it loose. 

Yup. Also try heating it very hot and put candle wax on it before welding a nut on it. I believe that worked for Drboost

This but beeswax.

Opti
Opti UltraDork
12/12/23 9:38 a.m.

Heat and a stud remover. I prefer a STRONG impact over doing it by hand.

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