I have been dragging my feet on writing this blog post because what I hoped to achieve was not what happened in the end. I wanted to take 8 intakes which had varying levels of filth and walk through a cleaning process that would mimic what anyone with basic shop tools could do at home. However, that is not what happened in the end. It is very hard to opt for a more labor intensive process like soda blasting when a blasting cabinet with zinc shot is readily available and there are 8 + large hunks of metal to be blasted. So, I hope this is helpful despite falling short of my intentions.
I began with 8 intakes and 2 air filter covers:
As you can see some of them were not too dirty while others were covered in old dried-on oil. The video below shows some more detail:
I began by blowing them off with the air compressor. This removed loose surface dirt. There are a lot of small spaces on these intakes, so I found taking a dry toothbrush and brushing some of the dustier spots helped the air hose remove more of the dirt. As you can see in the video below the surface of the intake began with some surface pitting. Drew kept reminding me that these intakes are from the 60s, and to some people being 60+ years is old. Personally, the closer I get, the younger 60 seems.
Then I prepped a tub for soaking them in warm water and LA's Totally Awesome Cleaner. Because these are made of aluminum, I wanted to be careful not to use anything that is very caustic. When I looked online, many people recommended oven cleaner but I knew better. Oven cleaner is very caustic and would turn the alloys in the aluminum dark grey and very cloudy. When this happens, the outer layer of natural oxides on the metal dissolve. I did not want to disturb the metal but I needed to get them clean.The caveat is that almost all degreasers have a caustic base. I tried two methods with the Totally Awesome (TA); the first method was to dilute it in warm water and the second was to use it straight.
I chose this cleaner because I was told it was a bit gentler than other cleaners we had in the shop like Simple Green which I was warned would definitely damage the finish on the castings. It is also ridiculously cheap and very easily found. I used a bucket heater to heat water in a tub. It was warm but not hot. The temperature gun registered the water at about 107 degrees. Then, I added about 32 ounces of cleaner to a 16 gallon tub.
Although the bottle recommendation was to use the cleaner undiluted on engines, it did cloud the surface a bit when sprayed directly on the surface of the aluminum, this was minimal however and would not prevent me from using it in the future. It was very effective at getting some of the black grease off of one of the dirtier intakes as you can see in the video below.
The undiluted TA had some mixed results. I am not sure I would go that route in the future. I think soaking the intakes in diluted TA was a good idea.
The one cleaner I did find extremely useful was carb cleaner. It is a solvent, not a degreaser and it felt like using a magic wand to make the old grease and laminated oil disappear. If I were only cleaning one intake, I would definitely pick up a can or two of carb cleaner. The video below shows the how easily the carb cleaner removed what the TA bath did not. It also leaves the finish on the aluminum intact.
The one solvent I had on hand that did absolutely nothing was denatured alcohol. I read somewhere that it can be used to remove dirt and old paint. It was beyond useless. One of the intakes had been painted red a long time ago and some of the old red paint was still lurking in the cracks and crannies. The alcohol was a waste of time (which is probably the first time that sentence has ever been uttered in the shop).
After I cleaned all of the intakes with cleaners, I pressure washed them.
This is where you start to see a lot of difference. See the 2x4 above? Before it was cleaned and pressure washed, it looked like this:
At the end of Day 1, this is what the situation looked like:
Everything was blown off with the air hose and left to dry overnight. Initially, we were going to soda blast the intakes because baking soda is widely available and soda blasting is the most feasible method for someone who is not doing professional restorations. However, we did not have enough soda and the last time Drew soda blasted things, he killed all of the grass in the area where he was working. If you want to kill weeds in the cracks of your patio, I recommend baking soda over salt. He had several pounds of walnut shell to use for blasting but supply chain issues caused the supplier to send a larger size than what was ordered. When we tried to move the walnut shell through the lines, it clogged them. So we changed gears again and moved onto zinc shot for blasting the intakes. Zinc is ridiculously expensive to use but it leaves a thin protective layer on the surface of the metal resulting in a gorgeous finish. This is where the plans deviated from the intentions. I intend to blast something with soda at some point but with eight intakes to do, I did not have the time or soda to get into that.
I was pleased with the end result. If I had to do this over again I know exactly what I would do and the process would go quicker.
Begin by blowing off the loose dirt. Then taking a small tooth brush to loosen any dried on dirt before using the air hose to remove more dirt.
Soak the intake in diluted LA Totally awesome cleaner and warm water, using a plastic brush to scrub what could be scrubbed off.
Use carb cleaner to remove hardened oil and tough stains
Let completely dry.
Blast with the most available media. The blasting is not critical but it definitely adds polish to the metal that makes it worth the trouble in my opinion.
Here are some after pictures of what it all looked like after cleaning and blasting:
And that 2x4 that was so dirty? It cleaned up very well and is already out of the shop. Here she is all gussied up, not bad for something 60+ years old.
This was a fun project. It would have been more fun if I was not doing 8 at once. This was my first time cleaning and blasting any sort of casting. It probably won't be my last, so if you have any suggestions on methods that have worked better for you please drop me a line in the comments.