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dav-1

head bolt headache

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dav-1

  I have a motor that came with 2 broken head bolts. i am sure that it is because the bolts are corroded to the aluminum head. i will have to remove the other bolts first but the broken ones will be the problem. i imagine the corrosion has them welded to the head. as they are side by side, i can't unscrew the whole head like i could if it was only one.  anyone have a secret way to get the bolts free enough to pry the head up over them? once the head is removed, a pair of vise-grips will deal with the bolts. will PBS loosen the aluminum/steel corrosion?

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RAC

See what you have first. Might not be as bad as you think.

 

 It'd be a little unusual for the bolts to be stuck hard in the head given the amount of clearance you normally have around a head bolt. 

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rich_kildow

Agreed, the head will most likely still be loose on the bolts, but will still be clamped down by those 2 stuck ones once you get the others loose.  My solution for stuck bolts of any type is time, whenever possible.  IMO, Kroil and WD-40 Rust Release Penetrant are more effective then PB blaster, but I could be wrong...it happened once before!  Spray them down several times a day and let it work, then about once every 5 spray sessions, give the bolt a little bit of working over.  Gently tap the bolt head with a hammer, try turning it both ways, and thing to get that oil down into the threads a little more.  

If you snap the head off, it will at least allow you to get the head off, but don't be too confident in vice grips.  If the bolt was stuck enough to break the head the vice grips are probably just going to slowly file the bolt off and dump those shavings into the cylinder.

My best result has always come from welding a larger nut to the snapped off bolt or stud and going from there.  The heat from the welding often seems to break up the corrosion a bit as the bolt expands more than the hole it is in.  Once cooled, it seems to usually do the trick.  CRC Freeze Off, or other cooling sprays, may help there as well.  

Worst case, you snap it off flush to the block and you have to drill it out.  Start small and work your way up, making sure your first hole is center-punched to start dead in the middle of the stuck bolt.  Once you are near the threads you may be able to pick the pieces out.  If not, drill for a helicoil and call her a day.  

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MrSteele

I agree, the corrosion in the heal should not be enough to freeze a bolt. If you do not have a hand held impact driver, get one. I tried to add a link but the site will not let me. Search for hand held impact driver. It is a tool that you can put a socket or other bit on and hit with a hammer. Penetrating oil, I use Gibbs Brand and usually always get things loose, let it sit and tap at first with your shiny new impact tool. More penetrant, harder taps.and try going both ways to get the oil worked in around the bolt.

Kobalt Impact Tool Set

If you break the head off, talk to an old mechanic to see if you can borrow a stud remover. It will hold much tighter than a vise grip,and the harder you turn the bolt, the more it grips.

1/4 to 3/4 in. Stud Remover | Princess Auto

I have no idea what the cost is, but I have one I have had for well over 50 years, that I have used maybe a dozen times since rebuilding a lot of tractor engines and flathead Ford engines.

And, if broken off in the block, drill or helicoil. However, in my experience, most studs/bolts will come out easily once the stress is removed, which you have done when you broke the head off

 

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MARK (LI)

It sounds as though you have not started on this yet...if the heads are broken off these bolts...once you take out all the other bolts the cylinder  head should just slide off past these 2 broken off ones....if not...at that point try different penetrating oils and a little banging ..and some heat...if they are then found to be stuck in the block...tacking a nut onto the end of each one works....just make sure the battery is disconnected....and as stated, the heat is a big help

Edited by MARK (LI)

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