Exhaust manifold bolt
Thread Starter
Burning Brakes
Joined: Sep 2010
Posts: 799
Likes: 26
From: Lexington Park Maryland
Exhaust manifold bolt
I was cleaning the threads on the cylinder head to install exhaust manifold on the 79 L48 I am reviving. when I go to the #2 cylinder exhaust, the long bolt that holds the bracket for the AC compressor broke and part of the bolt still in the cylinder head.
I've heard other "gear heads" mentioned about taking a nut and welding the remaining part on the broken bolt by build a weld from the broken part to the nut. Has anyone done used such technique? Thank you.
I've heard other "gear heads" mentioned about taking a nut and welding the remaining part on the broken bolt by build a weld from the broken part to the nut. Has anyone done used such technique? Thank you.
Intermediate
Joined: Jul 2006
Posts: 34
Likes: 1
From: Willow Spring NC
I've used that method several times on a number of items, as recently as last Saturday in fact. I've always used a MIG welder, although other setups should work equally well. Just try not to let that weld bleed over onto the block, as you don't want to weld it in place.
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
The trick I use is to weld a thick flat washer to the broken bolt first, it's easier to get good penetration verses welding through a nut initially. Then after the flat washer is welded to the broken bolt, weld a nut to the flat washer, let it cool and gradually work the bolt loose and tight till it comes out. If it breaks off, keep trying till it works. The heat breaks the rust loose and the broken bolt shrinks slightly from being heated and cooled.
Thread Starter
Burning Brakes
Joined: Sep 2010
Posts: 799
Likes: 26
From: Lexington Park Maryland
The trick I use is to weld a thick flat washer to the broken bolt first, it's easier to get good penetration verses welding through a nut initially. Then after the flat washer is welded to the broken bolt, weld a nut to the flat washer, let it cool and gradually work the bolt loose and tight till it comes out. If it breaks off, keep trying till it works. The heat breaks the rust loose and the broken bolt shrinks slightly from being heated and cooled.
Heel & Toe
Joined: Mar 2012
Posts: 20
Likes: 4
I've done this several times without a nut or a washer. On bolts broken off below the head surface too. Just tack a bead on the broken bolt with your mig, and keep tacking till you build up enough weld to grab onto with a vice grips. The heat from welding will make the threads loose and it will turn right out.
Burning Brakes
Joined: Apr 2008
Posts: 1,222
Likes: 93
From: shelbyville West Michigan
I have done it many times. it is my go to procedure for broken bolts when they are flush like that...the heat helps break the rust bond. other option is to put the manifold back on and use a bushing in the manifold hole to use as a guide to drill straight and centered on the broken bolt to use an extractor.
Thread Starter
Burning Brakes
Joined: Sep 2010
Posts: 799
Likes: 26
From: Lexington Park Maryland
I've done this several times without a nut or a washer. On bolts broken off below the head surface too. Just tack a bead on the broken bolt with your mig, and keep tacking till you build up enough weld to grab onto with a vice grips. The heat from welding will make the threads loose and it will turn right out.
