MTFCA Forum

I have one head bolt that is giving me a hard time.

It's the one in the center against the firewall. I can't get it to budge and I've also done a fine job of rounding it off a bit.

In other situations I might use a torch to heat it, but I hesitate to do that here.

I figured I can't be the first guy to have this problem with this bolt so thought I'd ask here.

Any ideas?

There are a lot of tricks in removing a stubborn bolt and in this case, it doesn’t hurt to use them all. Heat is good to break the bond of rust. I would take a propane torch and heat just the head of the bolt red hot and the let it cool. Don’t try and loosen while still red hot or you may twist the head off. Then spray on some “Blaster” bolt removal penetrant at the base of the bolt head. Since the head is rounded you can get a good grip with a Stillson (pipe) wrench. Use a cheater bar for more leverage and turn counter clockwise. Hopefully it will break loose before breaking off the head. Good luck. Jim Patrick

I had good luck removing Model A studs
using a low impact impact wrench.
Set it on its low setting and let it pound away for a bit.
I had bad results using a pipe wrench.

Striking with a hammer dead on or with a punch will help too causing shock release.

Dead blow hammer, heat, penetrating fluid, paraffin, go at it slow. My OP; stay away from cheater bar, good way to snap the bolt and no WD-40 unless it is the penetrating fluid type.

Something that works really well, (I use it on aircraft, where the surrounding structure is almost always either aluminum, or a really delicate forging you wouldn't want to touch with a hammer) but I think might not work for you due to poor access at the firewall. is the following:
Center as best you can on the head of the bolt. (If you have a centering drill, it would be much easier) (You can put a socket over the bolt head, and then use a piece of rod in what normally would be the socket drive cavity, that has a 18" hole drilled through it, if you know someone who can put a small hole through a little piece of rod that can be dropped into the drive area. If it's a 3/8" drive socket, then a piece of steel or brass that is 3/8" diameter will drop right in.)
Drill down with a #30 or 1/8" drill. Try to keep it as straight as possible. You want to generate a decent pilot hole that the next drill can follow.
Now drill down with a 1/4" or 5/16" drill. BE CAREFUL NOT TO DRIFT AT AN ANGLE. You want to remove metal from as near the center axis of the bolt as you possibly can.
If you have gotten a really straight hole, that is in perfect alignment, you can drill down again, even larger. If the hole is marginal, but you got it deep enough, you can try and see if the bolt will loosen. Rust expansion-locks the bolt, and this means there is a LOT of force generated between the bolt threads and the cylinder threads, to keep them seized. Once the core mass of the bolt is removed, all those forces now combine to shrink the bolt physically, so it actually draws away from the thread interface. The bolt is collapsing from the inside out.
Ideally, you measure another head bolt, and drill down until you stop just short of the end of the bolt. You can use a drill stop, or just mark the drill with a Sharpie marker, and eyeball it. Drill gently and slowly, clean out the chips often.
Once you have removed as much metal as you can, or at least removed some, the internal forces are much reduced, and the bolt may just turn out using only the head. In fact, you may be able to turn it out with an adjustable wrench if you have a couple of flats left, or a large Vice-grip pliers locked onto the bolt head.
Good luck with it!

On my brother-in-law's 25 tourer, that same head stud gave us grief. It came out easily for the first 1/4", and then seemed to lock up. It wouldn't go back down either. Lots of penetrant later, it finally broke about half way through the head. Now that meant the motor had to come out. Once we had it on the stand, the only way we could proceed was to rotate the whole head around and round on the top of the block, and wind the remainder of the thread out of the block.
It took some heavy work on a press to force the broken bolt out of the head. The bolt shaft had galled and bound solid within the head. Any other bolt might have let us drill it out in-situ, but not that one back one..

Allan from down under.

jiminbartow wrote: ↑

Wed Jun 10, 2020 9:01 pm

... you can get a good grip with a Stinson (pipe) wrench.

If you'll forgive me please; Stillson.

Use a 6 point socket or box end wrench. Helps with slightly rounded of bolt heads.

Allan wrote: ↑

Fri Jun 12, 2020 5:05 am

On my brother-in-law's 25 tourer, that same head stud gave us grief. It came out easily for the first 1/4", and then seemed to lock up. It wouldn't go back down either. Lots of penetrant later, it finally broke about half way through the head. Now that meant the motor had to come out. Once we had it on the stand, the only way we could proceed was to rotate the whole head around and round on the top of the block, and wind the remainder of the thread out of the block.
It took some heavy work on a press to force the broken bolt out of the head. The bolt shaft had galled and bound solid within the head. Any other bolt might have let us drill it out in-situ, but not that one back one..

Allan from down under.

Hey thanks Allan.

It turns out I have the very same problem, and I suspect that particular bolt never actually tightened down into the block. With all the other bolts out I can pick up the head enough and turn it clockwise with plenty of play pivoting on that bolt; the bolt is stationary with the head, it's the threads that are turning in the block, and they turn freely TO THE RIGHT.

I'm really not set up or ready to deal with a total engine removal so I'm going to have a few large friends over and pull it out and forward enough to be able to spin the head to get it off the block and then put it back immediately.

Thanks again!

It won't help now in getting the bolt out, but when you go back together, get some good anti-seize and coat the shanks of the bolts, and maybe a bit on the threads of the bolts. It will sure help in the future!

Ditto Bill!

I have a dandy electric heating element tool that will break it loose without damage. 110 volt hand held heater that has different diameter sizes of circular heating elements. You install the element into the handle slide it over the bolt head using the correct size, and turn it on the element will get red hot and transfer the heat to the offending bolt heating it up no flame no fire no damage. We use this tool on aluminum engines with seized head bolts.. I purchased mine from Snap On. I suggest you look around at your local automotive shops and maybe you can rent or borrow it. It takes about 10-15 minutes to get the head bolt red hot. Once its hot I wack the bolt dead center on the head then it should come out using a 6 point socket and a long flex bar and easy peasy out comes the bolt. At times we use Kroil penetrating after it has cooled a bit.

The reason the bolt comes out a bit then seizes is that the corrosion and carbon has bunched up as you are trying to remove the bolt and it becomes impacted not allowing it to go up or down. This heading element tends to break down the corrosion and crud in the hole. When you go to reinstall the head bolts you might consider a couple of things to help. 1st use a bottom tap to clear the hole but use an air gun before the tap, then blow the hole again and at times we have flooded the hole with Kroil and let it sit to soften up the crud. After the holes have been purged and retapped. Clean the threads of the bolts with a wire wheel. Personally I do not clean them with a die as that will make the threads a bit smaller and give you less holding ability. Lastly we do not use antisieze. On the exotic engines we service the manufacturers suggest 30 weight motor oil. Dip both the threaded end and the bolt head in oil as then dripping wet install the bolts..If you hear or feel a tightening or squeeking of the bolts when torqueing you have not used enough oil .

good luck,

frontyboy

frontyboy wrote: ↑

Sat Jun 13, 2020 10:18 pm

I have a dandy electric heating element tool that will break it loose without damage. 110 volt hand held heater that has different diameter sizes of circular heating elements. You install the element into the handle slide it over the bolt head using the correct size, and turn it on the element will get red hot and transfer the heat to the offending bolt heating it up no flame no fire no damage. We use this tool on aluminum engines with seized head bolts.. I purchased mine from Snap On. I suggest you look around at your local automotive shops and maybe you can rent or borrow it. It takes about 10-15 minutes to get the head bolt red hot. Once its hot I wack the bolt dead center on the head then it should come out using a 6 point socket and a long flex bar and easy peasy out comes the bolt. At times we use Kroil penetrating after it has cooled a bit.

The reason the bolt comes out a bit then seizes is that the corrosion and carbon has bunched up as you are trying to remove the bolt and it becomes impacted not allowing it to go up or down. This heading element tends to break down the corrosion and crud in the hole. When you go to reinstall the head bolts you might consider a couple of things to help. 1st use a bottom tap to clear the hole but use an air gun before the tap, then blow the hole again and at times we have flooded the hole with Kroil and let it sit to soften up the crud. After the holes have been purged and retapped. Clean the threads of the bolts with a wire wheel. Personally I do not clean them with a die as that will make the threads a bit smaller and give you less holding ability. Lastly we do not use antisieze. On the exotic engines we service the manufacturers suggest 30 weight motor oil. Dip both the threaded end and the bolt head in oil as then dripping wet install the bolts..If you hear or feel a tightening or squeeking of the bolts when torqueing you have not used enough oil .

good luck,

frontyboy

Appreciate the heads up about that tool. I'm going to keep an eye out for one.

In this case I'm virtually certain that the cause is a burr on the shank or the head and not corrosion over time, especially given that I never got any movement at all on that bolt relative to the head, but it is loose enough on the threads to allow the head to turn clockwise freely about an eighth of a turn (the only reason it's not more is that the firewall is in the way.)

I'll take a picture when I get it out and we'll see what the story is.

It is called an induction heater, and they do work well. The heat is concentrated on the bolt, BUT, when you have that bolt red hot, it will still heat the area near it. Not like a torch would but you may need some form of heat shielding directly above it. Auto parts stores can order the tool but they are not cheap, $350-500 range, eBay might be cheaper. And I will stick with the anti-seize on these antique cast iron parts. Oil will eventually run off, or bake into carbon, anti-seize will be there when you need it. Aircraft engines use a lot of it too. There are lots of opinions on lubricating threads of bolts that are going to be torqued to a specific setting. Most claim you want the threads dry to get the correct torque value, claiming that oil on the threads changes the value. I always wondered what the thread seal you need to use on small block Chevy head bolts did to the torque specs?