Cleaning aluminum oxidation and baked on oil

You might try Frozen carbon dioxde blasting it will leave no residue. The CO2 gets behind the stain/material and then sublimes or boils off under the stains to remove them. If you can find a place near you you can ask them. Don't know how expensive it is how ever.

 

Vapour blasting/honing seems to bring excellent results and is very gentle (even more so than wet abrasive blasting)

https://www.ferrarichat.com/forum/posts/146925196/

 

For a rough casting, glass bead blasting will work. Don't use alumina oxide; it's too abrasive for aluminum.

 

ice blasting

 

I have used Eagle One Mag Wheel Cleaner on my Dino castings with good results. You can usually get it at you local auto parts store for less than $10. As mentioned by another Dino owner, use a stainless wire brush if necessary rather than a brass brush as it will mark the aluminum.

 

If you don't want to remove the parts for bead blasting, Aluminum Jelly is a product I have used to remove corrosion and brighten the metal. Bursh it on, let it sit for a few minutes, work it in with a Scotch-Brite, and finally clean with water.

 

Depending on the car some castings were painted by the factory. What engine are you working on?

 

Update: Aluminum Jelly is no longer available.

 

My observation is
Anything that was diecast (sand diecast) got painted
Anything pressure diecast like (for example 308 water pumps) left natural.

 

A 1982 308 will have no painted castings. Most are pressure cast aluminum and are quite easy to clean however there are a lot of different techniques. With the engine in the car there are more limited options and some experimentation goes a long way. Here are some techniques that have worked well for me:

1. WD40 with a plastic brush or very fine steel wool. Keep the workspace well lubricated and give the WD40 time to work. It will literally draw grease and grime out of the castings which you can wipe or wash away.

2. Spray on scrubbing bubbles. Yes the same stuff used for your bathroom works really well on Aluminum. Again add soft agitation with a plastic brush and wipe and rinse.

3. Spray brake cleaner. A fantastic chemical available at any auto parts store and should be in the toolbox anyways.

4. Simple Green. The secret here is to make sure it is good and HOT. Totally a night and day difference compared to room temperature

5. Aluma-Brite. This is an aviation cleaner that is alkaline. Can be tricky to use and requires lots of experimentation but can work very well.

Whatever you do DONT use wire brushes or abrasives. It will forever ruin the factory aluminum. Any abrasive should be carefully tested and well lubricated to soften its potency. Good luck with your project

 

I don't know about Simple Green aircraft but regular Simple Green will etch raw aluminum and leave marks if you wait too long to flush off. It does work well but can't be left on too long.

 

As a cheap and safe cleaner I use mineral spirits in a pump spray bottle. It will not remove oxidation but is is it safe on aluminum or cured paint and does a really good job of easily removing old grease and oil with a little agitation using a brush. Just use it in a well ventilated work space, avoid any open flames and dispose of any saturated rags used for final cleanup in a safe manner.

 

Purple Power cleaner works pretty damn good on anything. Also Flame aluminum wheel cleaner diluted down with water will also work wonders.

 

This is good advice. The aircraft Simple Green is aluminum rated. Though I have not looked in to using it for this application I would see if Super Clean could work as well, that’s a potent but gentle cleaner that can be diluted down quite a bit. Vapor blasting would be fastest and leave the best finished result.