H3 Exhaust manifold troubles

[H3Vandal]

Hey, guys--I know a lot of you have worked on your H3 exhaust manifold, so I could use some advice at this point.

My '07 H3 had 3 manifold bolts sheared off flush with the cylinder head. A fourth broke with hardly any force when trying to remove it. A mechanic friend helped me drill & tap them out. When drilling one out, the small drill bit snapped off in the center of the bolt. He tried to TIG weld a nut onto it, but couldn't sustain a good arc & gave up after dozens of failed attempts. (He did weld a nut on the bolt that I broke, which was protruding half an inch--so I don't think lack of welding skills was the problem.)

After installing studs, now I can't get the manifold to fit over them. I can get it on the back few studs, but then the front ones don't line up, and vice versa. When I lay a straightedge across the mating surface of the manifold, it is close to straight but not quite. However, my understanding is that a small amount of warping is normal.

So, I have 2 questions:

1) Any other ideas for extracting the sheared bolt w/ a drill bit embedded in its core? Or is there any hope of the surrounding studs providing enough clamping power to seal it up with that one missing?

2) A new header isn't really in the budget right now, but I'm worried the stock manifold is too warped to reinstall. Does anyone have suggestions on how to get it to fit?

 

[CaseyS]

Slot the holes in the manifold slightly?

That's going to be tough on the stud but left handed drill bits may be worth a shot.

 

[08H3]

Ultimately the head had to be pulled on mine to get a broken bolt out. I know it's not what you wanted to hear, but after exhausting every option that's where I ended up.

 

[4speedfunk]

Take the manifold to a machine shop and have them put it on a mill...shave down the mating surface .005"-.010" to get it absolutely flat. This decking process is commonly used on heads and blocks to get them square and flat...shouldn't be a big deal. The process looks like this and should take about an hour of shop time...

On the studs/installation issue.... Try installing the studs AFTER the manifold is in place. I've had to do this several times, usually with head-studs on small-block chevys. You basically put the manifold in place against the motor, and then install the studs thru the manifold mounting holes, just like you would if they were bolts. Then after the studs are tight in the head (with high temp loc-tite)...put on the washers and nuts...and torque it down. This process is much easier if you use a set-screw type of stud (has an allen-head bung in the end of it). This will allow you to easily thread the stud into the block without having to double-nut it. Here's what a set screw looks like...

On the removing the broken stud... Hate to say it but, you will probably have to remove the head and get it up on a bench where you can work on it. Drill it out (use a drill-press or mill), and try an easy-out first. If that doesn't work...drill it out completely and re-tap the hole. Given the hassle to do all this, you might try your idea of leaving it alone. The worst that can happen is the manifold doesn't seal up and you need to pull it back off....which is what you would have to do anyway. Who knows...maybe you'll get lucky, and the manifold will work fine with the missing bolt (especially if you mill the mating surface). Good luck.

 

[SuperBuickGuy]

if you can't weld a nut to the bolt - you're pretty much stuck... sorry.

Also, the manifold must be perfectly flat - not "close enough" otherwise you'll be in the same boat sooner rather than later... worst of all, is if the leak is bad enough, it will erode the aluminum on the head not the cast iron manifold. That last one, means you'd be buying a new head... or get the manifold flattened now.