Exhaust flange bolts

[F4U-1A]

Those three bolts which couple my dual cat flange to the flange before my muffler, are the heads welded in there or are they splined and pressed in? Found my exhaust leak, two of the nuts with part of the bolts on the muffler side have broke off. All 28yr old OEM, staying attached with one bolt only now. Gap on passenger side between flanges making the Chevy sound like a Russian T34-85 more and more ( ya, I know the 34 was a diesel). All Good

 

[1998_K1500_Sub]

Those three bolts … are the heads welded in there or are they splined and pressed in?

On my 1998 L31 K1500, they were splined and pressed-in.

The C/K 2500/3500 L31s came equipped with larger exhaust pipes and I can’t speak to them.

Press / hammer / drill them out and replace with a 3/8” bolts, which is what worked for me. I used regular bolts and brass nuts.

An M10 bolt would be a tight fit, if it fit at all. An M8 might be a little skinny. 3/8” fits like a glove.

 

[Schurkey]

Bigass flange with two exhaust pipes?

You can kinda expect that the flange is warped. I considered drilling another bolt hole through that flange pair for a fourth bolt.

 

[F4U-1A]

Was on Y Tube finding tricks to punch them out. Not much room to play with, do not have torches or a lift. Just going to wrap mechanics wire around the center ( to hold in place) in case the last nut pops. Can deal with the noise (all country driving anyways) and it is hunting season. Chevy is going to be off the road in three weeks (Winter). Will ponder cutting off both flanges and just plumbing the four sections together. Good Times

 

[Cadillacmak]

You can kinda expect that the flange is warped.

YES! I bough a sheet of copper and made my own gasket because it kept blowing them out with a small warp.

 

[1998_K1500_Sub]

Was on Y Tube finding tricks to punch them out. Not much room to play with,

If you can free the y-pipe from the exhaust manifold, it’s easy to remove the entire y-pipe for repair.