Exhaust flange bolt

[98k2500]

Hey everyone. I'm a new member here from Western NY . Just bought a 98 k2500. 5.7 vortec. I'm trying to take the exhaust off. There is a flange just after the cat. The flange has two bolts up top and one on the bottom. Do these use actual bolts or press in studs? Can't seem to find a socket to fit the bolt, if it is an actual bolt that is. 17mm is a little sloppy. 16mm is too small11/16 is sloppy. 5/8 is too small. The bolt or stud heads are rusty so I can't really tell if it is a stud. If I cut the head off will I be able to get it out easily?

Thanks for any help.

 

[Zerio29]

Welcome to the forum!
Pretty sure that they're press-in studs from the factory - it's faster on the assembly line. I'd just pound them out and replace them with bolts with some stover nuts from any place that sells hardware. If you cut the head off you should be able to pound them out from the back with a punch. Otherwise just pound them back out the way they went in if you can get the nut off. Just be careful not to bend the flange too much.

 

[evilunclegrimace]

Cut them off, they are bolts. I did it to my '98 k1500 suburban.

 

[Zerio29]

Cut them off, they are bolts. I did it to my '98 k1500 suburban.

ahh... I stand corrected on them being studs.
but x2 on just lopping them off.

 

[98k2500]

ahh... I stand corrected on them being studs.
but x2 on just lopping them off.

Thanks for the replies. I'll cut em off tomorrow.

 

[evilunclegrimace]

ahh... I stand corrected on them being studs.
but x2 on just lopping them off.

Not all exhaust components are made the same all the time so you could have had studs.

 

[Zerio29]

Not all exhaust components are made the same all the time so you could have had studs.

Fair enough. I don't think I even looked. Just pulled out the grinder.

 

[98k2500]

I have read that some of these trucks have dual cats and some do not. Mine has the dual cats one before the flange I was talking about earlier and one is after the flange. Then there are two pipes down to one. After this there is nothing because the previous owner was going to replace everything.

So, I cut the 3 bolts off of this flange, which was not an easy task because there is one bolt that is pretty much up in the frame .

Anyway now I have more questions. I want to replace the cats, they look rough. Instead of buying the pipes that attach to the downpipes from the manifold that include the cats. Like the the one in the pic. Can I buy just pipes that attach to the downpipes (am I using the correct terminology here?) then buy two tubular shaped cats and connect them with clamps . Then add the muffler and tailpipes? I'd have to figure out a way to get the o2 sensors on there somewhere. Is there such pipes I could buy like this that don't have the cats built into them?

The reason I ask this is because the previous owner left 2inch( I think they were 2 inch) pipes and a dual in, dual out muffler and all the pipes including tailpipes in the bed of the truck. They looked like they would connect at the flange I cut the bolts off of.

Problem is the flange on the pipes the previous owner left is smaller and does not line up with the factory flange the bolts were cut off of. Even if they did line up the pipes the previous owner left does not have the second cat built into like the factory one.

I hope I am making sense. I am at work but I can take some pics when I get home. Just trying to figure out the best approach.

Engine is a 5.7 stock at the moment.

You must be registered for see images attach

 

[Schurkey]

I expect you could weld-up whatever you wanted, provided you have a big box of mandrel bends and enough straight pipe of the correct size.

One issue is that the Feds demand that you have the same number of cats, in the same location as stock.

Where you put the pipe connections--or if you even use some method of disconnecting the pipes--is up to you.

 

[98k2500]

I expect you could weld-up whatever you wanted, provided you have a big box of mandrel bends and enough straight pipe of the correct size.

One issue is that the Feds demand that you have the same number of cats, in the same location as stock.

Where you put the pipe connections--or if you even use some method of disconnecting the pipes--is up to you.

Does anyone know if there is a downpipe or maybe it's called a crossover pipe, the one that comes from the drivers side, i could buy that does not include the cat. Im hoping I could buy the driver side and passenger side downpipe and two converters and be able to bolt it all together. Not sure if it would be any less expensive than just buying the one I posted in the pic in my previous post though.