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The old steel bolts seized in aluminium housing challenge


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I extracted /removed  some m8 exhaust manifold studs from the aluminium head of a Renault Alpine V6 with the engine in situ.

I drilled the stud as near a possible central with a 5mm drill and then used a die grinder ( heavier version of a dremel) to slowly grind the stud away and picked the thread spirals out when I just touched the aluminium.  Took nearly 2 hrs per stud  but cheaper than  removing the cylinder head.

good luck

Happy new year

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21 hours ago, cackshifter said:

And also try tapping the stud cold with a hammer if you can, not ridiculously hard, but you are trying to break the corrosion bonds. We are all willing you on.

A decent punch and a good tap with a hammer can break the bonds - also a properly pointy centre-punch given a sharp whack really helps get the drill bit on centre if you're drilling it.

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As a biker, years of working on Japanese machines with cheesehead screws holding everything together means I feel your pain.

A trick I was shown a while ago was to get a strong solution of Caustic Soda and drip it onto the edge of the bolt. Capillary action will run it down the thread and it will dissolve the aluminium oxide locking the stud or bolt in, making it quite easy to release.

As soon as you have got the bolt out flush the hole with vinegar and then lots of water...

Hope that helps.

Simon

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3 hours ago, Junglie said:

A trick I was shown a while ago was to get a strong solution of Caustic Soda and drip it onto the edge of the bolt. Capillary action will run it down the thread and it will dissolve the aluminium oxide locking the stud or bolt in, making it quite easy to release.

I like the sound of that one, might be useful where heat could damage nearby plastics. 👍

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Hello Gentlemen!

Thanks for the additional suggestions. I particularly appreciate your tip and encouraging words cackshifter (What a great name too!! :)and your understanding, Junglie - great idea with the Caustic soda!

On 12/31/2020 at 7:09 PM, cackshifter said:

The warmer you dare get the aluminium, the better, as it expands more than steel. Ideally, hot aluminium, cold steel. So preheat a great idea. You might even try quenching the steel once you have welded onto it. And also try tapping the stud cold with a hammer if you can, not ridiculously hard, but you are trying to break the corrosion bonds. We are all willing you on.

Temperatures here have hovered around -5 C the past few days with spells of wettish snow and very hard freezing, so I am only just today (-3C but sunny and dry) able to start again on the task. Landroversforever requested some pics showing setup and location - so I'm attaching some here... taken , I add, a few days before the snow came. Both protruding studs were since sheared to surface level. Onwards...!!  :) 

Outdoor Garage.jpg

Workspace.jpg

Right.jpg

Left.jpg

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If you've already managed a hole down the middle then just keep going with progressively bigger bits until just short of the hole thread. The remains should then tap round with a small chisel.

HTH

Mo

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Given your temps I think you're really going to struggle to get enough heat into it. If you're trying the welding method again, I'd try getting the blowtorch on it first so that you can actually get some heat in the weld.

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