Removing a broken head Bolt

Hi, I’m helping a friend with his '89 4Runner. One of the head bolts broke off leaving 4" sticking out of the block. We haven’t tackled it yet beyond squirting some AeroKroil on it. Any other hints?

First thing that comes to mind is a dedicated stud remover. Put vise grips down on your list.

Do you think the bolt broke due to continued twisting when bottemed out? or is this a bolt that broke because it was week? any thread jamming going on?

Lets us know about AeroKroil what are its properties? I have never heard of it.

The bolt broke during removal. The head had too many problems to go into here but a number of the bolt shafts were full of soot and hard carbon. One bolt required close to 30 ft/lbs the entire way out.

Aero Kroil is made by Kano industries. It is largely used in industrial maintenance. The can advertises that it can creep into openings as small as one millionth of an inch and dissolves gum, grease, oil, rust and carbon deposits. After soaking it again with this I’ll try a good pair of vise grips. Any other suggestions?

Yes like I said, don’t start out with vise grips.

Apply heat to the broken bolt and then let it cool back down before removal is attempted. This will cause the bolt to expand when it’s heated, and then shrink back down as it cools. Sometimes this is enough to cause the bond to release at the threads, and will also allow the penetrating oil to get down to the threads through capillary action.


What is a stud remover?

Autozone has 3 different models $20,$25,$30 for sale not rent, made by the same company that makes vise grip.

I bought one at NAPA that uses a knurled cam to grab the side of the stud. It has a socket for a 1/2" drive breaker bar. It was pricey but it worked a beaut!

I would think a pipe wrench would be better than vice grips. I use a small one I can put a cheater bar on if needed.