Broken Exhaust Manifold Bolt Removal

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It is always a pain when a 30 minute job turns into a 5 hour job all bacuase of a snapped bolt. Fear not, help is at hand! In this short article: Broken Exhaust Manifold Bolt Removal, I will show you some of my favourite methods for removing not just manifold bolts but pretty much any snapped bolt, the same principals apply to 99% of all the snapped bolts and studs out there. Grab yourself a cuppa and you’ll have that bolt out in no time!

Method #1

This way works really well beause it introduces heat deep down inside the bolt. The downside is that you need to be able to access the snapped bolt well enough to drill it and weld a nut on. This might not always be possible, but if you think outside the box, maybe remove some extra parts you might get access. I have even removed a gearbox just to get access to it, simply beause it was less time and work to do that than it was to struggle with limited access.

The basic principal of this method is to drill a small hole deep into the bolt, then drill a bigger hole half the depth, then weld a nut on the top. One of the key things here to making it work is to get the weld as deep into the bolt as you can, as this will heat it up, and loosen it off. Watch the following video for a demonstration of this method:

I will say again, yes I realise this method requires good access and equipment that some people might not have, but it is a fantastic method if you can do it, I have personally had massive success using this technique.

Method #2

While I’m not going to condone hammering a Torx bit into a snapped bolt, I will admit that I have done it on many an occassion. I do have some “easy outs” or “reverse thread bits” but before I did I would use the Torx bit method. It is up to you, they are your tools.

The general idea here is to drill a hole nice and straight into the centre of the snapped off bolt, then either use a dedicated extractor tool, or a Torx bit, and remove the remaining stud. Watch this video for a comprehensive explaination:

Method #3

No-one likes drilling snapped bolts, so how about a method that doesn’t need any drilling? Well here you have it! Now I know at the start he says the kind of extractors I suggested in the previous method are a load of junk, but that’s open to opinion, I personally have had success with easy-outs, but maybe other people don’t. Anyway, we are looking at a method here that doesn’t require any drilling, just a welder! And it can be done in situ too!

The basic idea here is to weld a washer to the reamiander of the bolt, then a nut to the washer and unscrew it. There is a very important piece of advice in this one, and this is why I used it even though there is a load of swearing in it, the advice is “it might not work the first few times but it will eventually” and I really think that is the key to all these methods, if you keep going at it enough it will work. Here’s the video for it, a quick parental advisory here there is some swearing, but I figure that if you are at the point of removing snapped manifold bolts then you are well used to swearing by now!

Method #4

Sometimes you just can’t get the remains of the bolt or stud out, in which case you can drill it out re-tap the thread. This obviously requires the correct size of thread tap, so make sure you have that before commiting to drilling out the snapped bolt. Also note that in this video it is not being done on a exhaust manifold or cylinder head, but that doesn’t matter, the same basic principal applies, just be sure to check how deep you need to drill!

The general idea here is to drill a pilot hole, then move up to a drill size that is suitable for the size of thread on the snapped bolt. Then you clean or “chase” out the thread using the thread tap. Here’s the video:


As you can see there are numerous methods for dealing with a bolt or stud that is snapped off. This list is not really in order as such, but it is pretty much the order in which I think through the possible methods I could use. Think of the knowledge of knowing how to do these methods as tools in your toolbox, and what you want to do is choose the most suitable tool for the job. Sometimes you don’t have room for a drill, sometimes you don’t have a welder, sometimes it’s upside down, etc. So just think through what you can use to make it work. Don’t be afraid to remove the part completely if that’s what it takes, even dropping an engine down a few inches can give you all the access you need.

Also another thing to think about is if the first method you go with doesn’t work, what’s your paln B? What I mean by this is if you try removing the snapped bolt with a stud extractor and it snaps, well now you can’t weld it and it’s going to be a pain to drill the hardened steel out. Where as if you try welding it first and it doesn’t work, oh well, you needed a hole in the centre anyway for the other methods. Hope that makes sense, basically be prepeared to change your track if you need to.

One last thought on this, if you are reasing this and you don’t have a snapped bolt, maybe it’s a good idea to buy some tools that will help you should that situation occur.

That’s all I’ve got for now, let me know if I’ve missed any methods or techniques in the comments below!

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