BXProject

[mnde]

A couple of years ago I managed to shear off my thermostat bleed screw... while undoing the battery clamp with a ratchet spanner. The first blow partially undid it, the second blow sheared it off flush with the thermostat housing. So I did a bodge repair using a rubber floor protector from a clothes frame and a jubilee clip



What tool do I need to extract the remaining thread so I can fit a new screw?

Cheers,

Mark.

[jonathan_dyane]

The tool often recommended for this type of problem is called an easy-out, and the ideas is that you screw the device into the sheared-off item (it has a left hand tapping thread to chew a grip) and it permits the unscrewing of what has sheared off. What usually happens though, is that the easy-out then shears off, and you are left with a hardened and undrillable easy-out stuck solidly in the item in question. Not fun.

*However* the above course of events usually occurs when the thing you're trying to remove has sheared off due to it being rusted solid in place, and the fact that you sheared the bleed screw by hitting it rather than attempting to undo it means that it might just unscrew reasonably easily. *So* I would recommend that you get a suitable easy-out and give it a try, but go very easy, and if it is stuck instead proceed by drilling the bleed screw out (if you are able to find what size thread it has, you will be able to use the correct drill for that thread, and hopefully once it is drilled out you would then be able to winkle the remaining thread from the bleed screw out of the hole with something pointy, and all will be well.

I hope that makes sense...

Love the bodge btw...

[Vanny]

Stop buying cheap easy outs then mr dyane!

But seriously, easy outs are no use on a screw that small, also Easy Out is a brand name, i think the correct generic term is stud extractor. They can work well dependant on the bolt type (8.8's will usually come out, high tensile usually wont in my experience), also you need to drill a hole through the bolt before trying to use the stud extractor, thats the trick to them that no one ever tells you!

If the thermostat houseing comes off the car, then i would suggest removal and drill out the remains of the bolt, carefull drilling will leave the thread of the screw in the thread of the 'hole' and can then be carefully unwound using a pointy screw driver. You might even get a set of grips on the inside and continue running the bolt through the hole, but its likely that you cant get a grip on the other end either. If all else fails, find a short piece of steel bar, drill a hole through it, weld through the hole onto the stud to join pipe and stud together, then unwind with a pair of grips! Lots easier said than done!

[jonathan_dyane]

Isn't the correct term 'Spiral flute extractor'? A stud extractor is the thing you use first to shear the thing off before you reach for the easy-out's

I don't know what size the bleed screw is on the XU, but I have in the past used an easy-out (other brands available) sucessfully on the remains of a thermostat housing bleed screw on an AX diesel...

[Vanny]

maybe, but thats not a term i've ever heard.

Just having a google gives;
http://www.screwfix.com/prods/20084/Van ... OR-_-20084" onclick="window.open(this.href);return false;


or
http://www.justoffbase.co.uk/8mm-Stud-E ... tegory=202" onclick="window.open(this.href);return false;


But i dont think either snap the head off, whats the point in that, you've got a spanner and a delicate touch havent you?

[Philhod]

They are just called bolt extractors and have lazy LH flutes. Been using them for 50 years and never snapped one yet.!!!
As Vanny said, don't buy cheap shit.
Another point is that you use the correct one and drill the right size hole for the specific size of extractor. use lots of easing oil and leave for 24 hrs where possible.

If it's really corroded, drill a small hole as near to ctr as possible. Then keep going up in size till there is only a shell left (or you are getting real close to the threads). A fine chisel will see this out, then it's just re tap. mercats.

[jonathan_dyane]

I'm not that hamfisted, and don't make a habit of shearing things off (the last thing being CX thermostat housing bolts IIRC), but I do remember as a pup destroying a 2cv cylinder head with my foolhardy attempts to remove part of an exhaust manifold stud which I'd sheared off through youths impatience...

[docchevron132]

Ok, brass screw or plastic?
If plastic, piece of piss, if brass, not so difficult either!
The whole fucking thing is a press fit into the stat housing, and you can buy them new from Citroen for not alot.
I'd go that way TBH.

Slap new one in with a dab of sikaflex, happiness restored!

[Vanny]

I'm not that hamfisted, and don't make a habit of shearing things off

Well how dull are you? You'll never learn about pain until you really fork things up being ham fisted!

You could always weld it up, drill and tap a new hole?!