I want to replace the head gasket on an engine that last ran five years ago. The bolts are old, probably installed 40 to 50 years ago. Is there a technique to use in the removal of the bolts to minimize the chance of shearing one off?
I expect an expert will chime in here. The only time I have had a head bolt shear off is on a heavily rusted (boat anchor) engine. They are hardened and pretty tough. Has the engine been exposed to the elements? If not, I think that you are good to go.
an impact wrench at a low setting will work go back and forth with right and left button. it works for me!
I had, in the past, no good experience with the impact wrench but what always helped for me was, when the bolts are still tight, tap with a hammer a few times firmly on the bolts head. This will frighten the rust and free the bolt.
While yes you could still snap a bolt off, just use a regular 1/2 inch socket wench and try. When I pulled the head of my T that had sat a lot longer then that, I didn't even think about snapping a bolt and they came out just fine.
Don't get heavy handed and use a cheater bar.
I also tap on the studs when doing Model A's if they seem reluctant to give up their hold. If you want to try penetrating oil (NOT WD-40) you would have to build a dam out of modeling clay or such around the stud and pool the penetrating oil in it so it has a chance to soak down to the threads.
After you pull the head be sure to clean out the holes. I first use a smaller drill then the hole to break up any crud (you are using the drill to break up the crud not drill a deeper hole ) at the bottom vacuum that out then run a tap down then vacuum again. Then test fit the head without the gasket to make sure none of the bolts are bottoming out.
To add to the above, sometimes a bolt will move a little and then stick. In that case, you can squirt some oil under the head of the bolt which will run down through the head into the threads. After it sets a while, maybe overnight, try to turn the bolt in which will put some oil into the threads. Then try to back it out again. This might take a few tries, but will often save you from breaking off the bolt.
I use the penetrating oil around the stud and on the nut. I have been lucky with all the Model A s and T heads i have pulled, only had one broken stud years ago. Tim
Some spray & some tapping and go for it. By hand if you please. That's about all you can do. If they go they go and you can't stop it.
Have you even tried it yet? Don't worry about it. Give it a try. It may end up as a non-issue. Otherwise, as Charlie B. says, "If they go they go and you can't stop it". It's just part of working on old cars.
Thought I'd share an "Oh Crap" moment. Some years ago, was removing the head on a 47' Dodge (flathead 6) After giving all the bolts several wake-up raps with my "lucky hammer" (everyone needs one, can't be a new hammer, it has to be old to store up the luck!) Of 21 bolts, all cooperated with the exception of ONE! It broke with about 3/8" remaining above the deck. It was between two cylinders. Was able to get a good hold of it with my largest vice-grips. (both directions) No luck! I felt it was in too delicate of location to apply heat without risk. Shared the situation with an old mechanic. He said get some dry ice! I, being skeptical, "Okay, then what?" Get some aluminum foil and some rags, pack the area with the ice, wrap it up and let it set for a few hours. Did as he said, latched onto it, NOTHING! Tried opposite direction, It MOVED! A few back and forth with oil and it was done! YIPPEEE!!!! I honestly don't know if it indeed was the "trick" or the luck or both! Anyone heard of this man's wisdom? It was a first for me!
My Uncle Ernie would use r-12 freon to chill a stuck part. When the part warmed back up you could remove the bolt. May take two tries to get things freed up. Scott
When I encounter a stud that won't budge or one that has broken off I heat it up pretty good and then touch a candle to it so the wax melts down into the threads. Once it cools I have always been able to remove it. Don't know how or why it works but an old timer recommended it to me when I was trying to remove the studs in a block that had been sitting out in a field for years.
You could weld a nut to the remains of the stud or broken bolt. The heat would stay fairly local to the bolt and after it cools down should turn out easy. Even if the broken part is just below the surface of the block the weld will not stick to the cast iron.