Oh, dear...not holding out a lot of hope here! The head bolts on my T595 have been used before and are worn. They’ve all cracked half a turn...but on the second round one of the bolt chewed, taking two of the teeth off the star bit with it. I don’t think it’s worth trying a new bit, it would only trash it, so what are the options now? Would you carry on a couple of turns with the rest and maybe then dremmel the top off it? I hear about cutting slots on lesser bolts, but can’t see that working on head bolts that are still massively torqued. It’s a corner bolt, in case that’s relevant to head distortion, etc.
The bolt is obviously trashed so arc weld a nut or the old torx bit to it. Just take precautions for flying sparks and spatter. Drilling out and using an extractor is an option but on a tensioned head bolt you'll need luck on your side.
Lube and Maybe tighten the good bolts again would relieve some of tension on the bad bolt. Left handed drill bits might be last resort
Cheers, Pegscraper...wouldn’t the heat damage the alloy head, though? Would tapping a reverse-thread bolt into it be another option do you think?
Many thanks for that, much appreciated. What’s the practice with left-handed drill bits, is that the same as putting a left-handed bolt into the shaft of the head bolt?
Looking at the bolt pattern on your engine they look fairly easy to get to with the cams out of the way. Arc welding is a very localised heat source compared to gas. There is heat soak of course but not enough to cause damage IMO. I've used this on a car alloy head bolt and it worked. I used a piece of a fibre glass fire blanket as a shield. There isn't much depth there to tap a LH thread into the bolt head but it's another option. If the bolt has a steel washer under it, yet another option would be to carefully grind or drill off the bolt head leaving a stud to remove when the head comes off.
Anyone any experience of using something like this? https://www.toolstation.com/screw-b...E1cjnB0vhndbX_pUzIuTxZ-6FSPeXQ_BoCS2UQAvD_BwE
Stuart595. Yes I have used the easy outs and they are a bad idea. They tend to snap and when they snap in the bolt you won't even be able to drill. I still use them but if a bolt shows extra resistance I take them out. As said here before i would rather drill or Dremel the head of the bolt and try moulgrips. Joe.
Those easy outs are not that easy to use. Is there enough clearance at the corner to use a Stilson (pipe wrench?) I have used them on vehicle brake bolts where heat has accelerated corrosion. Leverage tightens them.
Cheers, Joe, I guess I’m looking to approach things in stages, and the ‘if it looks like snapping stage,’ may be a valid part of a spiralling journey to drilling the head off and risking warping the head from the sudden release.
Sadly not...it’s tight in there and the bolt top is domed and barely 5-7mm proud, and well protected by other head structures.
OK. Before ‘going large’ I would degrease the bolt (nail varnish remover!) and tor’s bit and araldite them together and leave overnight. If you have an impact driver to unscrew even better.
