How to loosen a bolt

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taxboy

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The bulb has gone on one of our outside lights but unfortunately I can't seem to shift one of the bolts to lift the top of the light off. It's circular with a slot head just to make life difficult. I think the lights are made of aluminium - corrosion is white.

Any advice appreciated please. I've tried wd40 and wrapping cloth round the head to try and turn with pliers but no joy. I'm loathe to try heat as the transparent panels are made of plastic

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Penetrating oil ( 3 in 1) may work better than WD40. The white is where the aluminium has oxidized. May be worth scraping the oxidation off first. Also a few light taps with a hammer to break any oxidation in the thread.
 
If all else fails, you could try using hot water as the heat source (isolate the light from the mains, just in case!) and maybe even sacrifice the bolt by using a pair of Mole grips (or similar) on the unprotected bolt head. If you do manage to get the bolt out, use a bit of petroleum jelly over the bolt head and on the threads to reduce the corrosion. LED lamps should last longer than filament lamps do so shouldn't need replacing for a while.
 
First - weigh up the cost of getting a new light against the trouble (which may not succeed) in getting the bolt/stud out.

File the head flat enough to apply a drill to make a hole in the stud to break it up or take a self tapper (which will also seize in time) to use instead.

PITA that is for sure.
 
Penetration fluid, but it should come loose if you hit/tap the end of the screwdriver as you turn, maybe try tightening first a little, once it moves then undo. Assuming you have a metal head on the screwdriver, needs to vibration/shock.

Or see if you can get/find an impact driver (old school thing)
 
You can get a freeze spray at Halfords which I've used in the past for bolts next to bushes where heat would damage the bush. It's not as effective as heat but still works better than nothing.
 
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arclight said:
First - weigh up the cost of getting a new light against the trouble (which may not succeed) in getting the bolt/stud out.

File the head flat enough to apply a drill to make a hole in the stud to break it up or take a self tapper (which will also seize in time) to use instead.

PITA that is for sure.
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Thanks for that. Unfortunately it's one of the pair on our gate posts so I would probably have to get both replaced if I go down that route
 
I suspect an impact drive with the force applied required is not suitable for the sort of lamp housing @taxboy describes. The one I had years ago was used with a lump hammer to best effect when working on my car :lol:
 
Box Brownie said:
I suspect an impact drive with the force applied required is not suitable for the sort of lamp housing @taxboy describes. The one I had years ago was used with a lump hammer to best effect when working on my car [emoji38]
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You are quite correct using a lump hammer on it would finish the lantern off [emoji3]

I'll pop out today and see if I can get some penetrating oil. Just to be clear the stud hasn't corroded that badly it's just welded in place [emoji54]
 
taxboy said:
You are quite correct using a lump hammer on it would finish the lantern off [emoji3]

I'll pop out today and see if I can get some penetrating oil. Just to be clear the stud hasn't corroded that badly it's just welded in place [emoji54]
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Wire brush it first to get rid of some corrosion and allow the penetrating oil to eerrr, penetrate.
 
taxboy said:
You are quite correct using a lump hammer on it would finish the lantern off [emoji3]

I'll pop out today and see if I can get some penetrating oil. Just to be clear the stud hasn't corroded that badly it's just welded in place [emoji54]
Click to expand...

I wonder could you post a pictures of a few angles.....this might inform some specific ideas rather than the general advice???
 
The suggestion of an impact driver is a good one, not for hitting down on as an aluminium light fitting is unlikely to survive that, but to give you something to hold on to while turning it, which will allow you to exert considerably more torque than is possible using an ordinary screwdriver.

Failing that, hex screwdriver bit fitted into a 1/4" drive socket and use the ratchet to give you more torque.

Failing that, a wood chisel applied to one side of the slot and tap with a hammer. It may not do the chisel very much good, so get one from the market / pound shop rather than using a decent one.

With all of the above accuracy is really important as the potential for collaterol damage is high!
 
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