So. What is the best way to remove seriously rusted bolts on headers at exhaust pipe connection? I don't have a torch. Grrr. Replacing whole exhaust. ..except for headers.

 

This may seem odd, but, if you have replacement bolts, use a long breaker bar and just break them off. Leverage is your friend. I've been able to break 1/2" stainless steel bolts holding my grill guard on using that method. I have a 4' length of 3/4" galvanized pipe that will slip over the handle of my socket wrench.

 

I've had good luck with such thing by first smacking 'em with a hammer to crack the rust, then soaking 'em down with a good penetrating lubricant (like Knock'r Loose or Freeze-Off) overnight, repeating again in the morning, and then after about an hour just going at 'em with a six point socket on a long breaker bar. Gotta use a good quantity of penetrant -- I spray it on four times at fifteen minute intervals, then start the wait time.

 

They are pretty much free spinning. Nut and bolt. Remember pipe to header bolts at the flange. Not header to block bolts. I'm thinking I'll have to cut them but with what and from where?

 

Can't you get an open end or box wrench (or locking pliers, pipe wrench, etc) on one head and let it jam up against something to prevent it from turning while turning the opposite one?

 

If those bolts are hard to get off, I typically cut them off using a muffler cut off air tool that uses a thin 3" abrasive cutoff wheel. It makes short work of them and I'll install new bolts coated with anti-seize.

 

Thread a nut on the thread end of the bolt, if there's room for it, leaving the bolt just a pinch below flush with the face of the nut, and so avoid distorting the threads too badly and making removal a pain. Then hold a hand sledge against the head of the bolt while whacking the thread end with another hammer. That'll transfer enough energy to crack the rust to allow the penetrating oil to get in.

 

The hex is probably rusted down so a socket will not fit it. If you cant turn it just cut the nut using a hack saw or die grinder with a cut off wheel. I had same issue with the bolts on the stock exhaust manifolds to the y pipe. Had to cut the bolt in half with a die grinder with cut off wheel. Bolts where replaced with stainless steel!

 

Now I know why the Jack-O who did my clutch cut the exhaust under the transmission. That's a tight fit with no line of sight. Picked up a cheap cut off wheel and cut the two bolts that i couldn't remove. Not a hard job just a pain when you can't see. I think the hardest part was removing rubber hangers so I could slide new unit into the intermediate pipe. Will replace intermediate, muffler and tail pipe next week or two... out of stoke locally.

 

WOW, what a difference new sensors make. pushed my MPG from 12 to almost 15 on the highway. Too bad it did nothing for the flapping rusted door panels.