How to clean up old/oxidised aluminium??

[J_K]

I'm just about to try and make a chargecooler from an old intercooler.
Obviously I'll be using nice new plate to make new end tanks and water jacket but the intercooler core is an old one and it's quite oxidised.
I could just wire brush and acetone the areas I'm going to weld but I'd like to remove as much oxidisation as possible from all the fins and tubes so that it looks a bit better and I'll get better heat transfer.

Anyone got any magic recipes?
All I can find on the net is white vinegar and cream of tarter recipes.
It's not a big intercooler (smart car) so I could buy 5 litres of vinegar to submerse it in. Which is my current plan..

 

[Richard.]

Those fins as you know are very delicate and baring a light spray with an acetone type solution Id be inclined to leave them alone as you may easily bend them. Regarding not so delicate parts you've pretty much got it. If your going to weld on an area where you do wire brush it make sure your brush is not the go to brush for everything else or you'll scrub more nastys in than out I keep a dedicated aluminium wire brush for the jobs where a scrubbing is essential. Acetone, degreaser, brake cleaner all work well just be sure it's instant self evaporating as some do leave a film/liquid behind.

 

[Shox Dr]

...amd make sure you only use a SS brush.

 

[Hitch]

Dont leave it in any caustic solutions for hours...like this was...

Was an extraction grille

 

[Richard.]

Dont leave it in any caustic solutions for hours...like this was...

Was an extraction grille

Jesus. My guess was it was anodised and left too long in solution???????

 

[backpurge]

As Richard has said, brush with a stainless steel wire brush

 

[500e]

Did that with a pair of Daimler V8 heads Hitch not a good outcome

 

[sardine]

A dip in hot caustic soda brightens up ally parts, but like above when you forget about bits, when you remember it won't be there it will have dissolved.

One Diesel lift pump in my case.

 

[pedrobedro]

Aluminium in caustic is a disaster even after you take it out if you don't rinse it really well as the reaction can carry on for ages.

 

[julianf]

caustic will, im sure, weaken the thin folded cooling, umm, sheet (?) too much

they may not be hyper efficient with a layer of oxide on the, but they will be a lot better than no fins...

 

[brightspark]

beadblast it

 

[gaz1]

you may laugh but heres a good cleaner for aluminium if your scrubbing it

grout this was done with smoke damage on aluminium

 

[hotrodder]

There's various spray on and rinse off 'aluminium cleaner & brighteners' about. The milder ones are often a blend of citric and phosphoric acid along with various surfacants, the stronger ones often include either a little sodium hydroxide (caustic) or hydrofluoric acid. I would've thought a strongish solution of caustic soda would make VERY short work of eating the fins and anything containing hydrofluoric acid needs treating with LOTS of respect

 

[J_K]

Interesting..
Hadn't thought about caustic soda..

The stainless "ali only" brush is a given.

I think i'll try a hot citric acid & vinegar bath then maybe dabble with a light caustic soda solution..

Thanks guys

 

[Richard.]

Id not use sodium hydroxide on those cooling fins if I was you. That stuff removes thick anodising in minutes and then if it's not removed sharpish afterwards it starts eating the Alu. Those fins are so delicate you won't get much chance with that stuff before it begins to eat them away.

 

[desmo11225]

Hi J_K
You have plenty of advice there, just one more thing, cleaning aluminium castings for MIG welding we found that you clean them, [wire brushing ] and weld them straight away, cleaning before lunch and welding after lunch was a failure even. All the Best desmo11225

 

[Richard.]

Hi J_K
You have plenty of advice there, just one more thing, cleaning aluminium castings for MIG welding we found that you clean them, [wire brushing ] and weld them straight away, cleaning before lunch and welding after lunch was a failure even. All the Best desmo11225

Very good point des. Alu regenerates its own oxide layer over a short time (1 hour, 2 at the most) so been over prepared and scrubbing it off long before welding is a pointless exercise.

 

[chevy2]

I find the 4-1/2" angle grinder poly discs good for precleaning ali before welding,
they're also real good at removing millscale from hotrolled steel.