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Engine basics => Engine set up tips => Topic started by: FLOYD CARTER on February 10, 2018, 04:21:30 PM
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I have an engine with slotted head bolts on the cylinder head. Of course, trying to get the head off, and a bolt promptly broke. Half of the slotted part broke off. Can;t get any other tool in there. I think the bolt is a 5-40.
Any ideas? Or am I screwed?
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Hi Floyd;
just do what you have to to cut, mill, Dremel, or whatever the rest of the bolt head off, then providing that you have the other head bolts out, the head will come off, then you can grab what's left of the broken screw with your favorite pliers or vice grips. If the leftovers are reluctant, apply PB-Blaster and a monokote heat gun and it will eventually come loose.
Type at you later,
Dan McEntee
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Floyd,
If you get the rest of the bolts out then you can heat the cast, put some DW40 on the bolt, then with lockjaw pliers grab the stub and turn it lose. If the other bolts are still in the head use the DW40 and heat the case before trying to remove them. I use a heat gun with a closed down tip and the inlet closed down to get max heat. If that doesn't work I have an industrial heat gun that will go to much higher temps but haven't needed to go there yet.
When you heat the case do it in a few stages where you heat and let it soak in, then heat again. really hit the spot by the bolt but not the bolt itself. I did this with a bolt the broke off at the top of the case. I used a cutting wheel to cut a slot in the stub and after heating was able to back it out (small diameter cutting wheel only left a little cut into the case itself).
Best, DennisT
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If I understand how Floyd is describing this I would be scratching head also
Some finned heads have pretty deep head bolt recesses with not much but a deep hole for the screwdriver
If just one half of the slotted screw head broke off flush.... there is no good way without a steady fixture and a mill to remove the remaining half of the crew head...no way to drill it off....no way to dremel a new slot
I might be tempted to soak with fav penetration oil and heat cycle well... reapply torque to all the other screws... then with a good sharp chisel the right width smack sharply and try to unscrew the buggered screw with the chisel...trick here I would hope is all the other torques screws relieve any pressure on the buggered one
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Yes. The screw head end is straight-sided, and that part is buried into a recess of the cylinder head.
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Years ago on a motor bike I had a deeply recessed screw that did same half break
I 12VDC battery Welded To the screw head a sacrificial screw driver... no soap.... BUT !!! inspiration... I went back and re-torqued ALL the other screws... deep soak in penetration oil... then mucho heat.... swift smack on the screw driver welded in-place,,, success!
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Pretty much anything you try will bugger up the cylinder head. My suggestion is to pack it nicely in a sturdy box and send it the motorman. It's the path of least resistance. Although if it is a Fox engine it may qualify for a hurl.
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The engine happens to be an Orwick 64. Parts are generally not available, so I can't afford to "bugger" up anything. Still operational even with broken screw. But I can never dismantle the engine for any reason.
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I'm in the same position as motor man for you Floyd. You probably still have my address from the tig welding I did for you. I could mill that out lickity split if you ever decide to.
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This engine is over 25 years old, with many, many flights on it. Compression is getting a little soft, but still OK. I considered having the cylinder chromed. Maybe someday it will be required. I'll run it until it doesn't go anymore.