1991 Silverado

My question is what is the teqnique to replaceing the right hand exhaust donut, the bolts are so frozen in there and I dont want to snap them. What should be done?

Spray PB Blaster on them. Let it soak in. Spray it again. Repeat as necessary.

//2000CAYukon

Heat it with a torch..

Go ahead and snap them. If they're really rusted up like 95% of them, it won't hurt to put new ones in, not to mention it will be alot faster and easier to just go ahead and ring them off, then put in $5 worth of new ones.

Yea probably does need new bolts but I beleive that the bolts are threaded right into the manifold so I dont want to break them off and have them stuck in the manifold. I do have a tourch so if they are cherry hot they may come loose. Any other suggestions? I hope this is the problem, see when the engine is cold and I accelerate I get this tapping, sounds almost like really loud lifters but when it warms up it gets better. I just started doing it within the last few months and now it had gotten more noticeable.

paxfam1

OK, then you've got studs, not bolts. If you snap those, you'll probably end up taking the manifold off to extract the remnants of the stud as it tends to break even with the manifold. My '88 had studs in the original manifolds and I had one get boogered up after fighting with it. I ended up putting shorty (stock replacement) headers since they are cheap. The best method for getting the nuts off is just to soak them repeatedly with some penetrating spray (WD40, spray silicones, etc) and let them sit for a while. Be judicious with the heat, trying too much with it can end up bending them. If it doesn't work after a few minutes or so of trying, let it cool and try again. It is possible as well that the nut will be frozen but the stud will unscrew out of the manifold. As a last ditch effort you can let everything cool off stone cold, crank the engine then begin to try to work the nuts. As the manifold heats up, you may be able to get the studs to unscrew before they heat up with the manifold. I got away with this once on a 64 impala. Once the stud came out, I ran a tap up the manifold to clean up the threads and used a new stud. The sound you're describing is very typical of a head pipe not being sealed. You can usually put your hand (carefully) up around the seal with the engine running and feel the gases leaking.