Broken tap in engine block.

[rtg]

I've just finished swearing... so I've now got to figure a way forwards.



Last job before the summer was to replace the thermostat. Simple job - 3 bolts. However, I removed one, but the other two snapped straight off. With a bit of persuasion one came out. However the lower one (as in picture) would not budge, even with WD40 overnight, heat etc.. So I've drilled it out. So far so good.

The threads for this hole were shot from drilling the nut out, so out comes the M6 tap. Again, with WD40, I tapped the hole, however on the last bit the tap breaks.

So, I've now unsuccessfully tried a tap extractor (3 pronged thing which just seems to bend) but am at a loss how to get this tap out (each idea I try the hole gets slightly wider ....) , and when it does come out, whether I tap a new M8 or use a stud secured with metal epoxy.

Suggestions?

Cheers, Richard.

[RayTVR]

You have my sympathies - been there, done that.

Thread which may be useful here

Edited by RayTVR on Tuesday 28th March 21:17

[steveo3002]

get someone to weld a nut on it then turn it out , wont take 5 mins if someone local has a welder

[GreenV8S]

steveo3002 said:

then turn it out

I think that would be a safe bet for a bolt - not so sure it'll be that simple for a tap.

[phillpot]

Snapping a tap in alluminium is good going!

looks like there's a bit sticking out, can you get a grip on it with Mole Grips?



Give me a shout if you want to buy an inlet manifold

[Boosted LS1]

Engineers have a tool which grips the outside of the stud on one side and then compresses and rotates it. I have one, it's ace. You need one of these, I'll try a google to see if I can find a name for you.

This:


http://www.knighton-tools.co.uk/acatalog/TEN2300.j...

https://www.google.co.uk/search?q=stud+extractor+s...

Edited by Boosted LS1 on Wednesday 29th March 00:09

[rtg]

Phillpot - how much for the inlet manifold?

I'm now resorting to the dreaded dremel, so any alternatives would be helpful.

Richard.

[Kitchski]

I'd go with the welding a nut on idea, but my concern would be if you managed to snap a tap (knowing what wky devices you normally have to operate them with) then a welded nut would probably just snap it again further down. You'd be there all week trying to drill it out.

Must have been VERY corroded in there for the tap to bind up and snap in the first place, so removing the manifold might actually be worthwhile anyway.

It's a bugger though for sure!

[Stig]

For taps, it's usually spark erosion to get them out. Did you bottom out the tap in the bore, or maybe it just got gummed up with the galvanic corrosion?

Not sure where you are - but this guy comes recommended: http://www.threaddoctorservicesltd.co.uk/

[phillpot]

rtg said:

Phillpot - how much for the inlet manifold?

I'll sort it out, make sure it looks okay, and if you end up needing it make me an offer I can't refuse

[AlfaSpider]

If you can still get hold of it could you introduce some heat to expand the aluminium slightly might just free it off.

[GreenV8S]

AlfaSpider said:

If you can still get hold of it could you introduce some heat to expand the aluminium slightly might just free it off.

It's probably either jammed with swarf, or galled. I'm not optimistic that heat is going to make any difference. I suspect the truth is simply that the torque needed to remove it is greater than the strength of the tap. If so, none of the usual techniques for releasing stuck studs are likely to help.

[Alan461]

Which direction were you turning it when it broke?
If it was clockwise then welding a nut on just might do it.
Anticlock, I would expect there's much less chance without it breaking again.
I would try a small twist drill in a hand drill down each of the flutes of the broken tap to clear out as much as possible then loads of penetrating oil and heat with your choice of extractor.
More than likely it will need a helicoil or similar

[rtg]

Thanks all for the help!

Stig - the ThreadDoctor looked promising, but his EDM machine is broken and will not be fixing it soon.

Phillpot - thanks - I'll take this inlet manifold off and see if I can free it on the bench. If not I'll give you a shout.

Everyone else - I'll be trying all ideas...

It's amazing how a 30 minute "I'll just remove these 3 bolts and pop in a new thermostat" turns into major exercise!

Cheers All!

[GreenV8S]

rtg said:

It's amazing how a 30 minute "I'll just remove these 3 bolts and pop in a new thermostat" turns into major exercise!

It's when you decide to take the dash out for better access that you know you've got a problem.

[v8s4me]

rtg said:

....It's amazing how a 30 minute.... turns into major exercise!...

This afternoon's 30 minute job was to tidy up the cable ties on the new fuel lines and pop the wheels back on. However, struggling under the car in poor light I managed to nip one of the brand new new hoses when snipping off a cable tie to re-position the hose.

One and a half hours later ........... Luckily it was the low pressure return line so it’s now got a piece of “olived” copper tube joining the two halves together. It was a nice tidy job, until this afternoon. Really annoying!

[RayTVR]

rtg said:

T
It's amazing how a 30 minute "I'll just remove these 3 bolts and pop in a new thermostat" turns into major exercise!

Yes, changing the thermostat resulted in a snapped bolt, resulting in a radiator and bonnet off, resulting in a set of new hoses as well as a load of chassis scrubbing and painting 'while I had access'. My 30 minutes turned to about 3 weeks.

[Boosted LS1]

rtg said:

Thanks all for the help!


Everyone else - I'll be trying all ideas...



Cheers All!

The tool I suggested above would almost certainly do it. Are you anywhere near Nottingham?

[glenrobbo]

Boosted LS1 said:

The tool I suggested above would almost certainly do it. Are you anywhere near Nottingham?

I think the New Forest is a quite different one to Sherwood Forest ???

[Boosted LS1]

glenrobbo said:

Boosted LS1 said:

The tool I suggested above would almost certainly do it. Are you anywhere near Nottingham?

I think the New Forest is a quite different one to Sherwood Forest ???

Bejesus, you may have cracked it :-) Thanks.