What are people's thoughts on sandblasting old alloy wheels to remove paint? Also an engine block including the gearbox, also to remove old paint? The parts will be bare before hand of course.
Cheers.

Just my opinion, its difficult to remove the grit from engine galleries and hidey holes. You can get a great finish from hot tanking.

I did blast my gearbox case for the last resto, and spent an age removing it from the blind thread holes and crevises. There's always a lingering doubt too that you got it all.

Nothing wrong with wheels however, as long as its soft media for aluminium. They will look a million dollars.

Just my opinion.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Soda blast them, then pressure wash the powder out, comes up unreal.

Have the engine hot tanked, it's standard at engine rebuilders after the breakdown as it removes oil, carbon and paint. If necessary paint stripper then wash again or just paint over it. If it survives the hot tank then it's probably not going anywhere.

Sand blast wheels only when looking to paint. For polished try a hot high pressure blaster then alloy friendly paint stripper then HP blast then polish.

My hot HP blaster has been the first step in all my builds and is does wonders.

I sandblasted my assembled engine to give it a freshen up paint job. I just removed the accessories and bolted blanking plates over and holes.
I have sandblasted mag wheels and after some wet and dry sandpaper and a polish they come up fine.

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Respect mine and I'll respect yours.

Use the glass beads you get from Repco, tradetools, etc. Works well, then quick W&D then polish. Don't use the corse pink garnet stuff, it's only good for bridge girders.

re sand or blasting an engine block or gear box housing. miss a few grains and all rotating or sliding surfaces will be worn out before ypur engine warms up. yours ric scott

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120bhp with 450kg just fun waiting to happen

We were prob. drunk when we set it up last and thought this will be a good idea

The Bengal garnet is great stuff in a medium grit, but yes, for steel parts only.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Yeah I think hot tanking is better now. I went down to my local engine builder and was convinced that he can remove 99% of paint in the process and if in not happy he will leave it in overnight.

If it's in bits, hot tanks the go. Any paint that doesn't come off after o/n dip, ain't coming off and you could be confident to paint over.
I did the glass bead wash on my motor. There was no repairs needed and I wanted to paint it and as KM mentioned, I sealed it up REAL good.

Regarding the alloy wheels, I have 5 quite original Contessa's that are sitting in my shed that I'd like to bring back to life. They are dull but look very straight and I don't mind a little hard work if it pays off….. What might be a plan of attack for this little project?

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1969 Mk1 Cooper S - "Madge" (the plastic surgeon is calling....)
1970 Mk2 Cooper S - "Vinnie" (Almost there....almost there...)

I think most people are saying that sand blasting is the go. I'm about to drop off mine today. I'll post some before and after pics later
Edit: the bloke that's doing it only does automotive stuff and showed me some samples of his work on alloy. He uses a 2 step process. The first is with fine media and follows up with glass beads.
Before pictures....

There needs to be a bit of clarification regarding blasting. There's heaps of different types and some may get 'caught out' using the wrong ones.

'Sandblaster's' use anything from fine sand to rocks. The fine sand is for paint/light rust/corrosion and the heavy stuff for really rusty beams machinary etc. Make sure the guy's doing it are experienced or you might end up paying for something that could end up scrap metal.

For alloy etc soda is the ideal stuff, it's fine and doesn't pit the metal. The next best thing is fine sand but can make for extra work when polishing is desired. There's other types of media, plastic beads , nut shell, ice etc, but these are more of a specialists type. I've seen purfectly good cars reduced to junk by inexperienced abrasive blasters.

The best idea if you're not sure who or what to use is to ask around, it's better to spend time asking than to spend more time trying to fix someone elses stuff up.

I did my s/h $20 ea Contessas with paint stripper, machined the gutter rash off, then wet sanded the shiny rims in the lathe with 400>600>1200 wet/dry paper.
Next I masked the shiny rim bit and etch primed the rest, and gave them about 6 or 7 coats of VHT's quickcoat acrylic gloss black.
They came up pretty nice.
No way I would sand blast Contessas.
[edit] or gearboxes. Grit problem as others said.
I found paint stripper works fine on the outside. But one S box I did recently had 45 years of Castrol black sludge stain inside. I got it soda blasted and it then looked brand new.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.