Exhaust manifold nuts. Remove how?

[Pablo M]

More trials and tribulations trying to get my head off. The car is in garage 15 minutes away so every trip over is frustrating in missing something lol. 
I’ve read a ton of faq posts on the nuts. 

Exhaust nuts. Rusted on studs. I shot them generously with PB Blaster last time I was there. Today I managed to remove 3 of the 4 top ones and #1 bottom nut pretty easily, but had to use a 1/4” drive socket given space limitations. All but one came out with the stud. 
The top #2 nut rounded trying to get it off. Vice grip made it worse. Hit it with fire. Hammered an 11mm socket on and got it off. 
 

The three remaining don’t allow a socket to be used. And my 12mm wrenches just start to round them. I’m not averse to cutting them off (angle grinder or hack saw) as I planned to replace them all anyway, but that seems extreme. 

What are my options?

There doesn’t seem to be a lot of space to work under there. 
Also considered undoing the manifold at downpipe but those are even more rusted. 
 

Edited September 16, 2023 by Pablo M
Spelling

[TobyB]

The closed end of a wrench, and an extension that slips over it.

 

An air chisel.

 

The gas axe.

 

Pull the motor first, take the head off, flip it over, and use viSe gripS.

 

t

 

[Son of Marty]

Yup, disconnect the 3 nuts on the down pipe and pull the head, from what I see here most people strip way too much off the head to pull it, it will come off with both intake and exhaust manifolds on it.

[tech71]

If you can get the manifold disconnected from the down pipe, remove head with it still attached. Easier to deal with that crud on the bench.

Probably shear the rusty manifold to down pipe studs but at least its disconnected.

I use a long ass extension , 12 point socket and an impact gun.

Super common problem

Edited September 9, 2023 by tech71

[Son of Marty]

1 minute ago, tech71 said:

12 point socket

Why a 12 point? wouldn't a 6 point be less likely to strip?

[Pablo M]

1 minute ago, Son of Marty said:

Why a 12 point? wouldn't a 6 point be less likely to strip?

Probably because you can't get a 6pt on the rusty nut. I had the same problem on the manifold nuts.

[tech71]

I seem to have better luck using a 12 point but probably doesn't matte, they usually just strip out anyway.

Then its time to break out the sawzall with a bi metallic blade and saw through the downpipe as high up as possible

Edited September 9, 2023 by tech71

[Pablo M]

4 minutes ago, tech71 said:

If you can get the manifold disconnected from the down pipe,

 

I tried that first. No luck. I suppose I could just go for it again with the idea of breaking them off if necessary. But then removing the stud left in the manifold will be difficult for me, where if I break a head stud I can double (thin) nut it and get them out. 

 

Still, my question remains: If I can't get a socket on it, can't get a box wrench on it, and I can't get a open end wrench to grab it firmly, how am i getting the nuts off?

[tech71]

39 minutes ago, Pablo M said:

Still, my question remains: If I can't get a socket on it, can't get a box wrench on it, and I can't get a open end wrench to grab it firmly, how am i getting the nuts off?

your not.... At least not until you get the whole hot rusty mess on your workbench, went through this recently, as stated I had to saw through the downpipe to get it all out. Your downpipe is probably in bad shape anyway and are available still I think, If not, someone will have one thats functional. I have a few.

Edited September 9, 2023 by tech71

[tzei]

I’d try extracror socket first.

 

 

then

 

Welder. ”Grow” the stud with few tacks and weld a nut on it. You may need to repeat this a few times (as it will break) until heat has done it’s course, nut holds and stud gives. 
 

Bottom nuts, in engine bay = difficulty 100.

 

Pull the head.

Edited September 10, 2023 by tzei

[MarcD]

I just did this job. I bought a set of extra long slim line wrenches and I was able to easily reach the difficult studs from underneath. The extractor bits above are excellent if you rounded off one of the old copper nuts. I like the ones by gray pneumatic. 

 

If you use the replacement studs from IE be aware of how they fit into the head. Mine had a very tight fit. I'm use to studs that go in almost finger tight where these required some not so insignificant effort. 

[John76]

Pablo,

 

Keep the exhaust (and intake) manifold on the head.

Disconnect the down pipe (cut if necessary) and pull the entire head off the block. 

Once you have it on your workbench, you'll have access to those stubborn nuts & studs.

 

John

 

 

[Pablo M]

Went this afternoon to get the head off. 
got the car up on jackstands and attacked the remaining nuts from below. 
some well placed heat took care of it! I was able to crack them open with heat and new needle nose vice grips. They came out with the studs though. 
All good, was able to get the head off. 

[Pablo M]

11 hours ago, John76 said:

 

John

 

 

What is that black piece on the manifold? Mine has bolt locations for that but it’s missing. Is it just a heat shield? 

[John76]

11 hours ago, Pablo M said:

What is that black piece on the manifold?

Yes, that is the heat shield for the Tii exhaust manifold.

Do you have the 49-state exhaust manifold, or the '75-'76 (CA) thermal reactor?

 

That big "bad boy" on the left is the thermal reactor needed for the biennial '76 CA smog test.

 

Disclaimer: Tii manifold (on right) for use "off-road" only!