I've got a 1996 Impala SS with the LT1, and it has a pretty nasty exhaust leak due to the fact that on #7 & 8 cylinders the exhaust manifold bolts have broken off in the head. The bolts appear to have broken off almost flush with the head. Can these bolts be tapped out with the heads on the car, or will the heads have to be pulled to perform this job?

 

Well, sometimes you get lucky and can use an easy-out to remove a bolt broken off flush. My experience has been I break the stoopid thing off and put myself in an even worse spot. You could drill it out in place and re-tap, but it would be hard to be sure you got it straight. If you use a drill bit smaller than the broken fastener to remove the material from the center of it, depending on how much material remains you can then use an easy-out or just a tap to get the threaded hole back to usable. The most fail-safe way to get it done would be yank the heads and bring them to a machine shop. Kinda depends on your patience, your tools, your luck, and your wallet.

 

The easiest way to do it on the car is to weld a nut to the broken bolt, let it cool a little and back it out. They can be drilled and tapped, but as said above, not real easy to do in the car. There are some experienced guys around here with torches and welders that can "blow" bolts out with a torch. Check around at some exhaust shops and ask if they have anyone that can do it.

 

Get a right angle attachment for your drill and a couple of left hand drill bits. Sometimes you can drill them out left handed and when you relieve the pressure with the drill bit the broken stud will catch on the drill and back itself out.

 

I agree with VZ sounds like the easiest solution. good luck with it.

 

I've thought about welding a nut to the bolt, but with the bolts being broke off flush, it probably won't work. There is a reasonable amount of room in the engine compartments of these big cars, so I might try the easy-out method before I have to yank the heads. Thanks for the advice.

 

I have seen some experienced welders ( more than me for sure! ) even weld a nut when the bolt is below the surface. They just build it up slowly. Good luck. Just be sure to try and drill EXACTLY in the middle of the bolt. If not, you could have coolant dripping out , and then bigger concerns! A center punch goes a long way when punched right!

 

I'd try to weld a nut on , as mentioned. Flush is fine, also
the heat helps loosen the broken piece in the head.

 

Common on LT1s. Usually doesn't cause a problem unless it's leaking and you can't get it sealed.

If my memory serves me correctly there is two bolts back there or something??? Or two threaded holes and some headers allow you to use that other hole? Maybe that's just the aluminum heads though.

 

I agree I've had great luck with lefthanded bits and broken bolts.

 

Double agree. Center drill the stud, hammer in an "easyout" and back it out. I drilled out 3 starter bolts that were broken off in a BBC boat motor! Upside down lying over the top of the motor w/a mirror and an angle air drill. I even amazed myself...but with tons of patients the bolts came out. The only other option was to remove the motor. I'd try this before welding and head removal.

 

Problem is you do not have the room on the Passenger side rear..... Drivers side you might make it.

There are 2 sets of holes back there, but the front set cannot be used with the manifolds.

The easiest I ever found was to use 308 SS rod to weld a nut, the weld will not stick to the cast iron, and it is easy to take out. Still real tight back there, so much so that my current 94 has the bolt still off, I just replaced the rest with the service replacement bolt package and left that one off.

No leak so far :-)

 

I have repaired this problem many times. Welding the nut on works good, but if the bolt is below the surface it makes it harder. So in that case you can get a piece of pipe that will fit into the bolt hole or about the same size. Ground to the piece of pipe. Stick a rod into the pipe holding the pipe tight to the bold let it burn in for a bit and then quit. 7018 is your best bet for a rod. Let it cool for at least 30 minutes. This will also cause the bolt to shrink making it that much more easier to take out. You can use either a vice gripe, pipe wrench to take it out or even weld a nut to the pipe.

 

Clayten that is a great idea I never thought of that. Ive welded nuts on etc... but the pipe trick would be way better.

 

You don't even need the welding hood on to do this, as you can't see the arc.