Drlljng out exhuast studs

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Xxl2

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I know I 'll have to door this sometime. What is a good drill bit and drill to drill out the exhaust studs in the exhaust manifold flange. Do not want to try to take the manifolds off. Been on over 25 years never removed.
 

Schurkey

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If this were me, I'd heat things up with a proper (Oxy-Acetylene, or Oxy-Propane) torch, and try to unscrew them before I started drilling. If you aren't adding extra oxygen, you're wasting your time. It's not hot enough to do any good. There's also the inductive-heating tools which have become more popular in the last ~3--5 years.

I'd attempt to heat the STUDS, not the manifold first. Make the studs glow. When they cool, hopefully they'll spin out.

If that didn't work, I'd heat the manifold but not the studs, and try to remove the studs with the manifold still hot.

Neither of those processes worked on the broken U-joint strap bolts in my pinion yoke on the back axle, though. I had to drill 'em. And I did not enjoy that a bit. They were broken too deeply in the hole to weld to. That's another great trick--welding a hex-nut to the broken piece and then using a normal wrench on the nut to remove the broken bolt. Again, you'd be heating the crap out of the broken bolt/stud, and not so much heat into the casting it's screwed-into. When it cools, they sometimes spin right out.
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On those bolts in the pinion yoke, I made a drill guide from ordinary brake tubing, sized to fit over the drill bit but inside the hole in the yoke. I used a reverse-twist drill bit hoping to catch the broken bolts and spin them out backwards. When the bolts would not spin, I just drilled through them with a 3/8 air drill to turn the bit. At that point, I was using bolt extractors in the now-hollow bolts. That didn't work. The ultimate solution was to use an "I" letter drill--the tap drill for the 5/16-24 bolts--and then spin a tap through the hole to put threads back in. The hope is that A) I drilled dead-center through the bolts, staying clear of the female threads in the casting, and B) I cleaned the old bolt male threads out of the existing casting female threads with the tap.

Two types of bolt extractors, the reverse-twist bit with drill guide, the Letter I tap drill, and a 5/16-24 starting tap. You'd be using the appropriate tools for 3/8-16, I think.
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Seems to have worked.
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Trailblazer exhaust manifold bolts, broken, with nuts welded to the remaining threaded shanks.
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You can play with penetrating oil. I do. But I have zero actual hope that penetrating oil does any good. I guess it's a matter of hope over experience. The thing is...I've never seen penetrating oil make things WORSE. Marinade away!
 
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Jonathanhicks

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If this were me, I'd heat things up with a proper (Oxy-Acetylene, or Oxy-Propane) torch, and try to unscrew them before I started drilling. If you aren't adding extra oxygen, you're wasting your time. It's not hot enough to do any good. There's also the inductive-heating tools which have become more popular in the last ~3--5 years.

I'd attempt to heat the STUDS, not the manifold first. Make the studs glow. When they cool, hopefully they'll spin out.

If that didn't work, I'd heat the manifold but not the studs, and try to remove the studs with the manifold still hot.

Neither of those processes worked on the broken U-joint strap bolts in my pinion yoke on the back axle, though. I had to drill 'em. And I did not enjoy that a bit. They were broken too deeply in the hole to weld to. That's another great trick--welding a hex-nut to the broken piece and then using a normal wrench on the nut to remove the broken bolt. Again, you'd be heating the crap out of the broken bolt/stud, and not so much heat into the casting it's screwed-into. When it cools, they sometimes spin right out.
You must be registered for see images attach


On those bolts in the pinion yoke, I made a drill guide from ordinary brake tubing, sized to fit over the drill bit but inside the hole in the yoke. I used a reverse-twist drill bit hoping to catch the broken bolts and spin them out backwards. When the bolts would not spin, I just drilled through them with a 3/8 air drill to turn the bit. At that point, I was using bolt extractors in the now-hollow bolts. That didn't work. The ultimate solution was to use an "I" letter drill--the tap drill for the 5/16-24 bolts--and then spin a tap through the hole to put threads back in. The hope is that A) I drilled dead-center through the bolts, staying clear of the female threads in the casting, and B) I cleaned the old bolt male threads out of the existing casting female threads with the tap.

Two types of bolt extractors, the reverse-twist bit with drill guide, the Letter I tap drill, and a 5/16-24 starting tap. You'd be using the appropriate tools for 3/8-16, I think.
You must be registered for see images attach


Seems to have worked.
You must be registered for see images attach


Trailblazer exhaust manifold bolts, broken, with nuts welded to the remaining threaded shanks.
You must be registered for see images attach



You can play with penetrating oil. I do. But I have zero actual hope that penetrating oil does any good. I guess it's a matter of hope over experience. The thing is...I've never seen penetrating oil make things WORSE. Marinade away!
I find that that " free all " works very good
 
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