Allen driver needed

Heat or cold or combination of both , blowtorch, oxy torch applied carefully.

Mig welding nut on top of fastener, heat helps free it and gives good surface to grip with tool.

Spark erosion was invented to remove snapped taps out of aluminium radar guides, its the expensive but ultimate way for removing HT steel from alloy.

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I think this is what you need:

Cic.

The screws could be fitted with thread locking compound. Suggest you use a Hot Air Gun.

From tds.loctite.com/tds5/docs/220-EN.PDF

For Disassembly

1. Remove with standard hand tools.

1. In rare instances where hand tools do not work because

of excessive engagement length, apply localized heat to

nut or bolt to approximately 250 °C. Disassemble while

hot.

Halfords don't have them in imperial.

No Thread lock used ... but guess dissimilar metals has caused the issue.

Many years ago I made my own using some spare sockets, spare allen keys, araldite and an angle grinder (to cut a suitable length of hex from the keys) - they're still going strong!

Dave

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Not much help if you're in a hurry. Have a look at this set which contains a 7/32" bit:

Cic.

You can get adaptors from various square drive heads to a hex bit holder, and then a standard hex bit of the required size would fit that.

e.g.

First off you might want to read this.

To use an allen key in your impact driver simply cut a length off the long end with an angle grinder disc and use it in a 7/32" socket.

Absolutely no point using releasing oil. The joint will be fluid tight.

You also must tighten back up each screw you loosen to take the load off the others and when all are free remove them one at a time.

If the screws are loctited in then applying heat for a while will soften it.

Car engine oil pumps are often held together with csk allen screws and I've had to remove god knows how many ultra tight ones over the years but nothing has ever failed to succumb to the right technique.

I'll bet you a pound to a pint if you cut a bit off an old 5.5mm allen key, belt that firmly with a claw hammer a few times and then just use a good tight fitting 7/32" key they'll pop out as easy as anything.

Tried some heat ... no difference (don't want to apply too much)

Bought new set of metric Allen keys to make sure it's a good fit ... still no go.

I have now ordered a socket driven allen key .... I'll give that a go with my pneumatic impact wrench .. on lowest setting and low air pressure.

My worry is it it rounded off the screws .... be a major issue to solve.

Not really. You just drill the heads off and you're left with a bunch of easily removeable threaded stubs after the cover is removed. Just use a drill a gnat's bigger than the screw shank and drill until the head spins off.

CSK hex head are about the easiest screws to drill out.

My worry would be damaging the Aluminum .... hope it does not come to this.

I have ordered a Hex socket bit .... I'll try walloping it a few times to seat it well, and hopefully loosen the fit. Contacted the manufacturer - he said this is very common ... suggests using a Torx bit and driving that in ... so it cuts itself in, plus the driving in will loosen .. and then it should come out.

He did add a standard 90 degree bend allen key is no use, needs a socketed driver.

You drill using a size slightly less than the thread diameter. You'll get a pretty good centre using the hex. A tap with a mallet on the back of the top part should then break the head off. If the top part can then be removed, a pair of grips on the thread should remove that. Perhaps soaked in penetrating oil overnight if corroded. Happens all the time with BMW disc brakes. ;-)

Yes - the torx trick can work.

Indeed.

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I would suggest that you start by using the new hex bit normally at first

- either T-bar or ratchet with steady pressure. There's no point in risking damage from a violent assault before you need to.

Cic.

My experience with impact drivers says they are less likely to break things than steady pressure. Although a very powerful impact driver could be different.

Not if they are titanium and molly coated. Can't see anyone on here coming across them though.

Dave

Fair point .... socket set of imperial hex heads arrived today.

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Given the comparative rarity of impact drivers it's obvious that the primary use of the type of tool which the OP has is as a hand tool. Few people routinely reach for an impact wrench for every tight nut, bolt and screw. I hardly ever use mine and of course there is often no access for an impact wrench, so it makes sense to try basic conventional methods first as I suggested.

Cic.