Sheared timing cover bolt - Suggestions on how to extract the rest?

mrtask

mrtask

Well-Known Member
I've sheared the long lower right timing cover bolt on my '71 V8. I drilled patiently with itsy-bitsy drill bits, slowly increasing the size until I could wind in a reverse-threaded extractor tool. You can probably guess what happened next; the tip snapped off and now I can't get it out. It is made of hardened steel so I can't drill it either. Who's got some helpful advice for me?
 
Have you got the cover off and do you have any exposed stub of the bolt to get hold off ?
I suppose this is one of the bolts near the water jacket - ie one of the bolts you can't leave out and keep your fingers crossed ?

Dave
 
Yup, the long lower bolt that goes into the right water way. Timing cover is off. Might use it as a drilling guide, as per helpful advice from the V8 owners forum.
There's only a little bit of the upper area of the sheared bolt face (7-o-clock to 5-o-clock if you see what I mean) protruding proud of the engine block, and the end of the snapped extractor tool also just proud in the middle of the bolt stub. Beneath the snapped end (5-o-clock to 7-o-clock) I've drilled around a bit further into the bolt stub to try and grab and remove the extractor tip, but if I drill any larger I'll start to damage the thread in the block.
 
Those extractors are far more trouble than they're worth, (as you're finding out), if a bolt is so tight it snaps, it stands to reason it will snap the extractor, and they're too hard to drill out. You can try to get it out, and you may be lucky, but at the stage you're at, it'll probably need someone with engineering experience and equipment to get it out.
 
Take the front cover off.
Get a small drill and do your best to drill lots of little holes around the extractor. With a bit of luck you aught to be able to get some water pump pliers on the extractor and twist it out.

With the extractor out, drill out the old bolt and then tap it to take some threaded bar. You can then put the timing cover back on with the normal bolts and use double nuts on the threaded bar.

I have a friend with an MGB GT V8 who has used this exact same method (same engine) its been drag raced for 3 years with this repair. The engine has been asked to swallow 150hp worth of nitrous oxide time after time and its never been a problem.
 
I realise it's too late by now, probably, but if you have a small bit of stud protruding then put a nut over the stud and weld it to the stud with an arc/mig welder and leave it to cool.
When a weld cools it shrinks considerably and that together with the heat will break the freeze on the bolt allowing it come out easily.

When you next put it all together use a good qality antsieze and then keep antifreeze in the cooling system, even if your temeratures don't warrant it. It is also an anti-corrosive agent.
 
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