Siezed exhaust flange studs

[pjq]

04 S 6 spd
Exhaust flange. Any suggestions how to get these stud bolts outs?Are they a tapered fit, a key way or just rusted in? Thats penetrating oil on the studs now.
I broke them when I twisted them off back in February to remove the engine.

[BYprodriver]

They should hammer out easily.

[pjq]

Bypro, thats what I was hoping but is not the case.
The thin head of the bolt is round not hex, could it be a bolt with splines on it?I don't see any spot weld on it, it is factory original.
One of the three flange nuts is spot welded to the flange.

[BYprodriver]

Yes it is splined with a interference fit. Maybe you can support the flange around the bolt with a pipe or socket enough to use a BFH.

[Trey T]

I used grinder and drill out

[pjq]

thanks Bypro, the pic shows what i've tried so far. With this 3 " clamp and penetrating oil and stricking the edge of the flange with a hammer still no luck. Its been under pressure for 1.5 hrs now. After your post, I like the BFH but can't support the muffler, I removed the little 3" clamp and now have a 8" clamp and tightened with a pipe. Still no movement.

What about grinding the head off and drilling out the stud?

If I need Oxy Acetylene I'll have to wait until tomorrow and take the whole muffler assembly to a welding shop.

[pjq]

Thanks Trey T that will be my project for this evening.

[Trey T]

upgrade it to spring bolt/nut type that Honda uses for their exhaust systems. You can find it locally

[bam914]

Heat the surrounding area around the stud cherry hot and hammer it out. It is the easiest way. I have done dozens of them this way.

[pjq]

Yes Bypro it was splined and the spline is the full depth of the flange. I cut them off and drilled them out, I wish I had oxy acteylene.
Trey T I'll check with Honda tomorrow.

Here is the head of the bolt and a portion of the splined area of the bolt.

[Trey T]

you don't have to get it from the stealership Honda, get it from autopart store like autozone

[pjq]

I used 8x30x1.25 bolt (8 hardness) with copper nuts, and copper never-seize. At the auto parts stores and honda and vw I could not find an exhaust bolt of this size. They did have studs but no bolts. After talking to one of the muffler shops they said a #5 or #8 bolt is good, DON'T use a stainless bolt.