Best way to remove this snapped head exhaust stud?

[100DashSix]

I was doing a final torquing of my exhaust manifold when the stud twisted off, leaving a half inch sticking out.

What's the best way to remove this? Here's a picture:



(click for bigger)

John Twist has two useful videos where he talks about using an oxy/acetylene torch and wiggling the stud with vice grips. Is this the best way to approach this? How about welding a nut on the end and unscrewing it?

I don't know if the stud is frozen in the head, and I fear making this situation even worse. I was about to start the car up after a year of slowly replacing the clutch. :frown:

 

[JPSmit]

I have a stud removal tool like this - works a treat.
Removal tool

On nasty studs (and broken bolts) I first heat then, then cool quickly with water then heat again and touch a candle to the stud which wicks the wax down the threads then use the tool. No problems so far.

 

[Silverghost]

A method that may work for you:

If there is enough thread showing, thread two nuts onto the stud. Then tighten the outer nut against the inner nut. Now back out the stud by turning the INNER nut only.

 

[100DashSix]

I've used that method in the past, Peter, but unfortunately there's only 1/8" of thread or so. I doubt it'd be enough to get it off.

John-Peter, what sort of removal tool is that? The site doesn't have too much detail, so I don't know how to search for it.

Looking at the Haynes manual, I now see the manifold nuts should only go to 15-20 lbf. I tried to crank it up to 30 to 40, misremembering the number. D'oh.

 

[JPSmit]

John-Peter, what sort of removal tool is that? The site doesn't have too much detail, so I don't know how to search for it.

You can maybe see it better here. This is Harbor Freight. It is basically a socket and the opening has kind of knurled insides. I hammer the thing down on the stud and then as you turn it "tightens" on the stud. Not sure how else to describe it. I have two sets - metric and imperial - four each that cover pretty much what I need. Found them in a bargain bin somewhere and while I don't use them often, when I need them they are awesome.

 

[100DashSix]

That sounds useful! But perhaps it's too good to be true? I wonder if a manifold stud could be too frozen for that to work.

I currently have enough stud to grip with vice grips, but it seems possible that I could further break the stud, and remove that option. Does the bolt extractor socket seriously damage the metal?

 

[aeronca65t]

Rocking the stud back and forth <span style="text-decoration: underline">very</span> gently with a <span style="text-decoration: underline">tight</span> vise-grips has always worked for me.
And as John Twist has said, use a little heat. Even a propane torch can be useful.

The key is to be patient and to just put a small of amount of torque on it. Don't try to turn it....just apply a small amount of CW and then CCW twisting. It could take over 5 minutes of rocking before you see a perceptible turn from your efforts.

 

[JPSmit]

That sounds useful! But perhaps it's too good to be true? I wonder if a manifold stud could be too frozen for that to work.

I currently have enough stud to grip with vice grips, but it seems possible that I could further break the stud, and remove that option. Does the bolt extractor socket seriously damage the metal?

As I said, I have had good luck with it. I have used it on manifold studs as well as bolts that were even more frozen. I wouldn't say the extractor "seriously" damages it any more than say, vice grips. Obviously the stud is ruined but it is anyway.

Heat is your friend here as Hap notes - I just have a propane torch. Just go slow and know that there are various ways to accomplish the same thing.

 

[Roger]

I'm with Nial, and would add that while you've got it hot and are twisting, a sharp rap or two with a 2lb hammer. directly on the end like you were driving it in, can help it to break free too. It acts a bit like an impact wrench.

 

[100DashSix]

Thanks for the tips. I may start with Mapp gas and twist it very gently. If that doesn't work, only then will I go on to oxy/acetylene, which I'll have to find at a welding supply store, I suppose. Should _that_ fail, I'll try one of those bolt extractors, or another largely mechanical method of removal.

 

[100DashSix]

Woot! I got it out. I used Mapp gas (carefully) and very slightly wiggled vice grips on the stud. It took two attempts and about three minutes of total heating. The engine was rebuilt in the 90's, so I suppose the stud wasn't completely frozen in there.

My path is now cleared to get the car running after a year of sitting, and I can finally test to see if my clutch repair job was successful.

 

[drooartz]

Nice work!

 

[aeronca65t]

Nice!

By the way, if the stud is broken off "flush", my preferred method is a left-hand drill bit that is about 75% of the diameter of the stud.

Use a good, sharp punch to make a starter dimple (and that will loosen it a bit as Roger mentioned).
Since a left-hand bit drill will be turning "backwards", it will often unwind the offending stud once it has begun drilling into it.

 

[100DashSix]

Hopefully I'll never encounter such a situation, but I'll keep that tip in mind for when I inevitably do.