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I'm changing the head gasket on this truck. Here you can see the exhause manifold bolted onto the upper intake, which I am trying to remove.

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And here is the reason I would like to remove the exhaust manifold from the rest of the exhaust.

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One of the bolts that holds the manifold onto the upper intake has had its head snapped off. There is very little clearance around the bolt with the broken head so I can't remove it without taking off the A/C condenser and maybe even the passenger side wheel well.

But If I can disconnect the exhaust manifold from the rest of the exhaust I can still pull out the upper intake, with the exhaust manifold still attached. The problem is those bolts are rusted.

enter image description here

I've sprayed a ton of PB Blaster on that bolt, hit it with a wire brush, and used a torch on it. It won't budge. So can I just cut it in half with a hack saw? If I do will that separate the exhaust manifold from the rest of the exhaust? I'm hoping that once the bolt is cut in half it will be easier to remove.

Here's an image of the exhaust manifold. I'm pretty sure I can get away with just cutting through the bolt. Will it be hard to get the bolt out once I cut it? I imagine it will be easier because I'll have it out of the truck and there will be half as much resistence.

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    If you do end up cutting the bolts, you're committed. You'll have to replace them, and if you can't get them cleanly out, you'll have to re-bore the holes in a larger size.
    – Cullub
    Commented Jul 8, 2016 at 16:15
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    Nice use of photos to make your question clear (and useful) to all. Thx. Oh and that A/C part is an Evaporator Core. The condenser is the heat exchanger in front of the radiator.
    – zipzit
    Commented Jul 8, 2016 at 17:33
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    Have you tried heating the flange? Those flange bolts look ready to break anyways you may as well just cut them.
    – Ben
    Commented Jul 8, 2016 at 19:29
  • I did heat the flange. idk if the indentation on the bolt is from heating that area or the bolt is made that way. I was just using a butane torch.
    – dolphone bubleine
    Commented Jul 8, 2016 at 20:44
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    When heating the bolt, you need to heat it until cherry red ... I mean RED. If you don't, you won't get anything out of it. Then when cherry red, it needs to be quenched somehow. The PB Blaster should do the trick, but beeswax would work wonders. The idea is when it hits cherry red it expands the bolt, then by hitting it with beeswax (or PB), you are shocking the bolt and flange to separate. It also allows the lubricant to leach into where the threads are to lubricate. If you aren't heating it up until it's red, it won't want to come apart.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented Jul 9, 2016 at 11:31

3 Answers 3

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I would do as you suggest and cut them. Once you have got the manifold off the engine, you could drill the old bolts out and then just use a normal pair of nuts and bolts to fasten the exhaust to the manifold. Alternatively you could re-tap the manifold for some new bolts.

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  • This is exactly what I did and it worked great. I just drilled right though and used a new bolt, a lock washer, a nut, and red loctite.
    – dolphone bubleine
    Commented Dec 7, 2016 at 2:39
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Try torching them again. The only bolts that I couldn't get off with a torch are the ones that snapped. If the bolt didn't turn an orange glow, you're not getting it hot enough.

Cutting them off, as has been pointed out in the other answers, won't let the bolt magically slide out because a bolt that won't budge is a bolt that seized (corrosion and rust between the bolt and the threads have made them almost one single piece of metal). The only option you have left after cutting them off, as has also been pointed out in other answers, is to drill the bolt out, and then cut new threads inside. You need steady hands and a good eye to line yourself up perfectly straight, and you'll need a tap and dye set.

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  • Good answer. Just to add, the reason fusion occurs is because oxidation and heat cause two different metals to "rust". Thus eventually making them stick together. There are some copper anti-seize on the market that hold up well on exhaust nuts and bolts. Exhaust bolts become extremely brittle as well because of the rapid temperature changes they experience. It makes the bolts and nuts more dense and causes the stripping and snapping off scenario like this. This is why I shy away from exhaust work lol
    – cloudnyn3
    Commented Jul 9, 2016 at 15:44
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You COULD drill the head enough or grind them just enough to get the rest out. Slip it off and see if you can get a pair of locking pliers on it after you get it off. If you don't regularly use tap and dyes, it's really easy to ruin your head. I would just try to pull it off and try to grab what's left of the bolt with the pliers, if not then you'll have to cut them so they're flush with the head, and drill them.

ETCG How to remove broken fasteners.

This guy explains several methods quite well.

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