The secondary air (smog) check valve has blown and I would like to replace it. I have searched the forums for the best/easiest way to replace it with no luck. I have read that the pipe it attached to will twist of you are not carefull. I would think that placing a plumbers pipe wrench on the pipe would prevent the twist. Does this sound doable? Is there a better way? Maybe a little heat?

 

I removed the air intake, MAF and secondary air pump when I did mine. The check valve is fairly deep in there, but can be accessed and removed from the top.
It is attached to a pipe which coming from under the engine, which will move if not secured when wrenching the valve off.
I would suggest letting some penetration fluid soak in there, then hold the lower pipe steady with a wrench (I used an adjustable) while removing the check valve.
It is straightforward enough, unless the check valve is really stuck on there. Mine took some effort to free up, but didn't need any heat.
Once the check valve has been removed it's just a case of getting it all back together again.