Engine Bay Aluminum Cleaning/ Polishing

[Screwdriva]

Greetings,

My W115 240d has its cooling system out, waiting for a couple hoses and such. Wanted to take this time to clean and polish the front engine aluminum on the housings, air intake and valve cover.

Is there a best practice method to doing this? I've purchase some Purple power, degreaser, fine sand paper, cellulose solvent and wire wool to clean the aluminum corrosion off from where the hoses mount onto the thermostat and water pump housings but have never attempted to clean/ polish large aluminum surface areas before.

Anyone who's done this or has seen a tutorial, please do share!

Thanks in advance!

[SD Blue]

Personally, I would stay away from most of the items you mentioned. The best things I've used were cleaning vinegar and green scotch-brite pads. Everything else caused more corrosion than it eliminated.

[Zulfiqar]

For cleaning grime safely, some orange citrus cleaner or mean green works really good.

For brightening, macs alu brightener from napa is hydrofloric acid, (very dangerous stuff). But cleans aluminium amazingly good. (Test yours in a tiny spot first as it may blacken some alloys)

Usual citrus stuff works great.

To shine it up, buy a fine carbide sponge from grainger and use some vinegar as mentioned above for a real nice result.

[Bengoshi2000]

Watching this thread with interest...

Minor thread Hijack: On my 300d, the PO at some point, sprayed the engine bay with some sort of clear coat. Now, years later, it's turned yellow/brown and is peeling up. Any suggestions on how to clean that mess up?

[Diseasel300]

Be careful with the "purple" degreasers. They'll turn the aluminum dark and if not rinsed well, will make it develop a fine powder in a few weeks. The reaction is chemical and requires way more elbow grease to reverse than using a better degreaser in the first place. Make sure whatever you use specifically says on it that it is safe for aluminum and will not discolor, I can say from personal experience that "Purple Power" brand will turn the aluminum in the engine bay jet black if you leave it on long enough to soften really baked on grime. I've had excellent luck with a product called "Oil Eater". Loose grease and grime simply melts off, the harder stuff is softened to the point that it breaks loose with a toothbrush or paintbrush. I haven't bothered polishing anything in my engine bay, my cars are drivers and not show-queens. They're gonna get dirty anyway!

[Diesel911]

Originally Posted by Bengoshi2000

Watching this thread with interest...

Minor thread Hijack: On my 300d, the PO at some point, sprayed the engine bay with some sort of clear coat. Now, years later, it's turned yellow/brown and is peeling up. Any suggestions on how to clean that mess up?

Depending on how flaky it is on solid items like the valve cover you may be able to use compressed air using a thinner tube on the end of the Nozzle (the sell them usually as a set with or with out some cheap air nozzle) or a pressure washer. Obviously where you direct the pressure stream has to be taken into account.