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Resto tips- Cast aluminum cleaning ideas

4K views 19 replies 14 participants last post by  Dr.Jeff 
#1 · (Edited)
I'm looking for some suggestions on the best way to clean/protect the cast aluminum intake manifold, trans and other key parts in the engine bay. Some quick googling and I see all kinds of ideas from oven cleaner, to ajax, to white vinegar, mag cleaners and various acids. I'm sure some of those will work but then leave the aluminum more raw than before and prone to faster deterioration/staining. On my mustang alternator that was heavily oxidized I used a brass wheel on a dremel and drill with decent results then rubbed in some WD-40 on which left a short term coating on it. It looked 100x better than what I started with and acceptable nice used result but still off from factory new or restored. I'm also looking in to ASC-50 military spec stuff to seal as some recommend by some. Short of media or vapor blasting what has worked well for you to produce and maintain a factory type of finish on or off your car? Echassin has had some excellent tips over the years to reproduce factory finishes with painting mists etc. so that's probably the direction I will head on many items. Appreciate any input!
 
#2 ·
For stuff that already mounted and you're not willing to disassemble, I've resorted to a good degreaser (purple power or ZEP purple degreaser) and some light mechanical or manual wire brushing. For anything that wasn't already mounted and I wasn't worried about heat transfer like an intake manifold, I had them blasted and powdercoated an aluminum color because I got tired of cleaning them too.
 
#3 ·
Echassin has had some excellent tips over the years to reproduce factory finishes with painting mists
Thanks for the kudos. For those unfamiliar, this seems to be as good a time/place as any to show long-term follow up on the technique, which consists of gasoline/brushes, followed by a misting of Duplicolor 500 degree Aluminum engine paint. The key is not to apply full layers of paint, just mistings until silver, not enough to ever peel. The result is oddly persistent similar to unwanted overspray.

May 2nd 2007, just after completing reassembly:


Today:


Admittedly this isn't a daily driver seeing winter duty, but for the type of fair-weather use a lot of these cars see, I think it's reasonable to say the result is "permanent". I don't know if it's any better than blasted bare aluminum would be after similar time and use, but it's certainly no worse.
 
#4 ·
I see someone does it like me. [emoji23] I have to paint the housings without the bolts and brackets, then clean the bolts and install them. I think it looks a lot better and more professional.
I use the engine paint method, it seems to work well, so long as you clean and degrease very well. I like to use starting fluid for the last spray before painting to get the last grease off. Seems to work pretty well.

Sent from my S60 using Tapatalk
 
#5 ·
I constantly clean engine compartments with a spray bottle of Maintex HD Cleaner/Degreaser and a couple coins at self serve car wash. Customers like when they spend a lot of money for me to tinker under the hood and it's clean when I'm done. I do not think you'll find a cheaper/better product. I like Oil Eater too. Both can be purchased at Costco in their janitorial supplies aisle. https://www.costcobusinessdelivery....egreaser,-160-oz,-2-ct.product.100284325.html

I've never had any luck painting aluminum. Since I pressure wash my engine compartment regularly, I'm not concerned how bright the aluminum looks. You may want to try muriatic acid but read the precautions and do not trust anyone like me on the internet.
 
#6 · (Edited)
muriatic acid is dangerous to metals
you can get fairly high concentrations from ZEP CLR gallon bottles

most cleaners have sodium hydroxide, which is common for household cleaners
purplepower or simplegreen are pretty common automotive cleaners
B12 used to be stronger, and works on smaller projects

most degreasers only handle light work
power washers or scrubbing is usually required

the best way is an ultrasonic bath bucket
more extreme using sand/glass/media blasters
or good old fashioned elbow grease and a brush, brillopad, wire wheel


transmissions are an alloy of aluminum and magnesium

protecting aluminum:
coat it with paint, clear or color
or anodize it
bare aluminum will oxidize (rust)
aluminum oxide is white

that said, the surface aluminum oxide is protecting the aluminum under it
removing the surface oxide re-exposes it to oxygen and it begins to deteriorate again very quickly on a chemical level
 
#7 ·
Most degreasers which require dilution will corrode AL, if not diluted enough, or if left on for an extended period of time.

Sodium hydroxide is the active ingredient in most HVAC coil cleaners, and oddly enough, hair relaxer. Also an alkaline formula that will eat aluminum.

I actually used this stuff on a transmission after pressure washing the heavy stuff off and scrubbing it down with gas. It was more of an experiment to see what would happen.... I already had the coil cleaner. The coil cleaner turned the AL a dull gray and the drive flanges and bolts went to a bronze color. Being that the AL was etched, the paint should stick pretty well... don’t forget most self etch primers contain acid, to bite into the raw metals, promoting adhesion.

Normally, I’d have media blasted it, then painted. As mentioned raw AL will oxide if not top coated with something. It also will soak in oil like a sponge.

-Todd
 
#10 · (Edited)
I use wd-40 and spray everything down specially the connectors. I drive it to a Car wash and use the power wash on engine cleaner. If it is really grimey I use "LA's Totally Awesome" from the family dollar store a buck a spray bottle cheap and most effective, Spray rub a bit and rinse... works well After Pressure washing I remove the connectors off the ICM, and Hall sender and Spray with CRC Wire-dri, as well as the plug wires cap and Hall sender... (I also take care not to soak them with the washer). It can pit paint so remember to spray let it work a minute scrub and rinse.


Before totally awesome"




After:




After the cleaning and it has dried, I usually coat it with a misting of wd-40.


For aluminum, if it is off the car I used Totally awesome and let it soak. spray it again, then power wash it.
for my Tranny's I sprayed them with Duplicolor Gold, and then clear, it holds up for quite a few years.

For parts that are on the car as in manifolds, I usually after power washing use a brass tooth brush or SOS pads to get them a bit shiney. If the part is off the car and rather large, I use a Brass wheel on my Drill.



Every part that I remove I clean, prior to re-assembly. to make it look spiffy, I use a mixture of turtle was Protectant F21 Super Protectant mixed 50/50 with Distilled water. Place in a fine misty sprayer, shake well, then mist it over everything.....Heavy drops you can wipe. Close the hood of the car, and let sit overnight...in the morning open the hood and look at the pretty shiny things under your hood .....

Oh after cleaning with totally awesome I usually look like:


under side before.


after
 
#13 ·
Interesting how this topic has generated so much response. The same discussion just appeared on another forum recently with similar results.

In reply to the mention of using various products like "oven cleaner, to ajax, to white vinegar, mag cleaners and various acids". I found lots of such suggestions (and many more) online and decided to play around with them - just to see. Pretty much all of them completely failed. I can't believe there are so many people saying that it worked, no way. Even some that made sense from a scientific perspective were not very effective.

In the past there were chemical hot dip tanks that were safe for aluminum materials. But like most things that gave good results it has been banned. Those commercial parts washers (like huge dishwashers) haven't given good results for me, but others like it.

However I think there is another question that needs to be answered first. That is what's your goal; a concours show car, a simple clean up on a daily driver, or somewhere in between?

The best overall results I've found are with media blasting, as others have said. But be aware it can be difficult to get all of the media out of critical areas afterwords. So non harmful media like soda are best in those cases. And I also agree with the comments that a freshly cleaned surface needs to be sealed to prevent further oxidization and dirt collection. I've found some sort of coating like paint works well. If you want to retain the original aluminum finish maybe either try a clear paint or another clear protective coating like "Sharkhide".

For the intake manifold in particular I like Gave's suggestion of ceramic coating. Again either aluminum color or clear. Cerakoat has a "air cure" formula that you can do yourself without an oven.
 
#14 · (Edited)
However I think there is another question that needs to be answered first. That is what's your goal; a concours show car, a simple clean up on a daily driver, or somewhere in between?
Thanks Dr. I'm thinking of keeping this in clean/excellent driver condition in line with the 52K miles on it and not "restored" shape. I aim to clean things up as I go since my engine is out I'm just not sure how far to go and what works best to clean/protect. So that said sounds like I'm the "somewhere in between guy". Most items already look nice with a gentle cleaning so that's the direction but don't want to ruin anything in process or miss an opportunity to make it look better or nearly new. Clearly theres no perfect answer but I'm hopeful that you all have found a few nuggets you are willing to share that worked well for you.
 
#15 ·
I think I'm in the same vein: I use gas and mists of silver paint because the result is good enough, it's cost effective, and it doesn't stall work like farming things out would. I do some blasting but it's really tedious and messy, plus the various media get consumed really fast and they're really expensive.
 
#17 ·
Did this a few times on aluminum parts; degreaser, media blasting (aluminum, then glass) and finally 95% gloss clear powdercoat.

It's a bit much for a daily driver, but it's fun and satisfying to do. :laugh:
 
#18 ·
If you are on a mission to destroy money and can take parts off of the car, I just load my Harbor Freight Parts washer with PSC 1000 from Tractor Supply: https://www.tractorsupply.com/tsc/product/crown-psc-1000-parts-cleaner-5-gal

It works about as well as brake cleaner but is better on the lungs. You can barely smell it and it won't burn your garage down. I added an oil filter and bigger pump to my parts washer and it chugs along nicely.

I usually refinish intake manifolds and valve covers (on my Alfas) with VHT engine enamel. Holds up well if you glass bead blast first: https://www.vhtpaint.com/high-heat/vht-engine-enamel

They have two aluminum finishes - nu-cast and universal. Both look good
 
#19 ·
That’s the stuff that I use.... I think it’s just mineral spirits aka stoddard solvent. I still find myself using gas in a turkey pan more than the parts washer.... way cheaper and way more aggressive, but it won’t pull stains from AL.

I have a lot of leftover Armex soda... I’ll need to try that in the blast cabinet. I originally bought it for a pot blaster, but I was making a huge mess and it killed a portion of my lawn.

-Todd
 
#20 ·
There is an old expression from chemistry that "like dissolves like", meaning the best agent to dissolve something is another form of that same substance. In our situation we are talking about old grease and oil deposits that have collected other dirt, etc. So another form of petroleum distillate will work well to remove it. That can be anything like paint thinner or gasoline - basically solvents. This is the main reason why the "safe" water based cleaners do not get the same results. Naturally there are tradeoffs in using petroleum solvents, such as health hazards, risk of fire, or environmental issues. But 'bang for the buck' it is difficult to beat the results you get with a solvent that is readily available in large supply at a low cost per gallon - namely gas.

As was stated it is extremely difficult to remove the "stains" that are found in cast aluminum or cast iron. Particularly that brown color you usually see inside the engine or transmission cases. That's because the porous surface of the cast metals collects stuff deep into its 'grain' and it doesn't just wash off. That is where physical removal helps, such as abrasive blasting. Effectively you are removing a very thin surface layer of the metal, and therefore the stains with it. Which is why a protective finish like paint works best after blasting; otherwise there is still a oily film in the pores of the part, and the paint won't stick well.

But for a daily driver that you just want to clean up and make look better without breaking the bank, a good clean with any solvent or degreaser followed by a coat of paint will give good results that will last fairly well. The better you are able to clean and coat it, the better it will look and last.
 
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