I'm not sure if this is the right area, but here goes.

I have a new y pipe, but I can't remove the old one from the manifold. I have used pb's penetrating spray and nothing, it's still stuck. I am trying to keep from removing the manifolds.

It is a 2000 ZR2 blazer.

 

There really is no easy way to do this. You either break them or you dont. Heat helps, but it has to be high, rapidly applied heat, not the propane torch variety. Rapid cooling helps to break the rust bond on the threads too.

 

Yup, no easy way when your working on rusty exhaust. If you don't need to keep your old y-pipe you could probably cut it off. That might give you more room to work on it. I can't remember how hard it is to get to the bolts, but if its hard to get a tool on the bolts, cutting it off as high as you can might help.

 

Yeah, heat worked for me, even out of a small propane (heehee).

 

Your best way is bring it to a muffler shop, see if they'll burn off the nuts for you or burn out the studs and replace with new, save yourself a whole lot of aggrevaition at this point, usually an independent shop will do it, for a couple bucks. Because your gonna need an acetylene torch w/oxygen- (cutting torch). Good luck.

 

alright thanks for all the info and I now realised I will have to take off the manifolds.

 

When I was taking my manifolds out, I found that it was easier to disconnect the pipe with the manifolds still connected to the heads. I also put the blazer on jack stands, and removed the front tires for easier access. A 3/8" drive ratchet and a long extension wasn't enough to break the torque, even after spraying some penetrant to losen it up. Had to use a longer and larger tool for more leverage. They're tight, and luckily mine didn't snap.