removing exhaust manifolds with stuck bolts

[Austrian455]

Hey guys,

Today I removed the exhaust system of the Centurion.
Now I know what took the power.
I will post some pics in the next days.
I never saw such a bad exhaust system.

But my main problem is that all 4 bolt that hold the exhaust system to the manifolds broke.
So I have to remove the exhaust manifolds to get the threads free and recut.
But the bolts which hold the manifolds to the heads are also rusted.
I brushed off most of the dirt and rust with a wire brush and sprayed all bolts with rust remover.
Are there any other tricks to get those bolts loose without breaking them?
I really want to keep the cylinder heads on :shocked:

[MichelHaak]

Making the bolts red hot could help but that's always tricky in the engine compartment. It doesn't always work by the way. The only advice I can give is to stay calm, take your time and use alot of WD-40... I replaced mines and 1 bolt broke in the middle, but that's not a really big problem since it doesn't leak gasses after 1 year.

[Robroy]

As for the 4 broken bolts (2 on each side if I understood this right...) between the exhaust system and the manifolds, can’t you drill the pieces out with the manifolds still on?

I messed up one of the threads too when replacing the exhaust system but took the easy way out with a bolt and a nut on the other side…maybe not so professional :rolleyes: but it works ;)

[Austrian455]

Michel, I had the bolts heated with a autogen welding equipment. Now I sprayed all the bolts with a very good industrial rust remover we use in our company on heavy machines like trucks and other big stuff. I also hit the bolts with a hammer to get them loose.
Tomorrow, when the rust remover did it´s work I will try to get them off.

Per, I tried to drill them out. That would work on one or maybe both on the driver side. But not on the passenger side.
I also want to use the orig. threads without a nut on the backside.
We will see. If I get the manifolds off I will take the chance having them off and paint the heads, sandblast the manifolds and paint them (cast iron look), and I will do some serios porting in those manifolds. They have to flow if I really do all this work ;)
But thanks for the advice.

[Robroy]

Peter, you probably know this, but just in case you don’t;
There is a special tool for getting out broken bolts (see the pict) without damaging the thread.
You drill a hole in the middle of the broken bolt and then you screw the tool in until it bite, then with some luck the bolt will follow. I have used this kind occasionally with success.
Doesn’t help much though if you can’t access to drill….. :tonge2:

[Austrian455]

Per, I know this tool.
I used it on my Fiero´s engine when I rebuilt it.
I had some broke header studs. It worked fine.
I will try. Maybe I can drill a hole in those bolts with a longer drill.
I don´´t know if they offer something. I know you can buy long drills for stone.
Maybe also for steel.
Thanks again.
I will keep you posted what happened.