Cleaning oil stain from cast aluminum?

[SANTA3013]

While detailing this engine bay I could not get these oil stains out of the top of the engine. I believe the material is cast aluminum. I cleaned the engine using Meguiars Engine Cleaner. How would you get the oil stains out?

 

[tuscarora dave]

What was your process? Did you spray the cleaner on and simply rinse it off? Did you spray it on, allow to dwell then agitate with a brush before rinsing?

It may just be a case of not enough mechanical agitation, could be you need a stronger cleaner, could be both.

I've had great success using wheel acid on parts like that in the engine bay. There is a very important process in doing so though.

I spray the wheel acid on a totally cool, dry, pre-cleaned engine and above all I am very focused on keeping everything consistently wet with the wheel acid as I agitate with a brush after a minute or so of consistently wet dwell time.

So it's spray the wheel acid on, allowing a minute or two of dwell time while respraying if necessary to keep the cast aluminum parts thoroughly and evenly wet with the product the entire time this process is carried out. After the few minutes of dwell time I begin brushing the parts with a long and soft bristled brush being very careful not to splatter the wheel cleaner on myself or other areas of the car.

I am fully gloved up and using a respirator and most importantly eye protection while agitating (actually through the entire process start to finish) the parts in a fully and consistently wet manner. So it's spray (did I mention keeping everything consistently wet?) dwell, brush carefully while continuing to spray the wheel acid on the parts being cleaned in order to keep everything consistently wet.

Once everything has been cleaned sufficiently with the wheel acid, it is very important to rinse everything well with flowing water for at least 5 minutes as acid tends to permeate and cling to cast aluminum no matter how long you rinse it off. As such, you must follow this thorough rinsing with a alkaline based all purpose cleaner to penetrate and neutralize the acid that will naturally cling and permeate into the cast aluminum.

This neutralizing process is very important!! If not done, the aluminum will turn white as it dries because of the acid that will be left behind in the cast aluminum.

Keep in mind that you can also get this whitening effect if using a super strong concentrated alkaline cleaner such as Zep Industrial Ultra Concentrated Purple Degreaser.

I like to use Zep Citrus Degreaser cut 50/50 with water for this neutralizing procedure.

After the acid cleaning and thorough rinse, (while everything is still wet with water) I spray on the Zep Citrus and follow the same procedure as was outlined in the acid cleaning instructions above. That is, spray on thoroughly and allow a few minutes of consistently wet dwell time, brush agitate while keeping everything consistently wet by continuing to spray the Zep Citrus while agitating with the brush. In the end, I do a thorough water rinse then give the cast aluminum one last wash and rinse using a bucket of car wash & Wax concentrate mixed at regular car wash duty concentration. The wax in the wash & wax leaves behind a nice layer of protection against oxidation of the newly brightened cast aluminum.

 

[FUNX650]

•It looks like oils/contaminates have "soaked into"
the pores of the cast aluminum.

•The safest way I've found to "pull out" all of the oil
from the pores, is to put the parts in a heated ultrasonic-cleaner overnight.
-That...or put them in the oven for an overnight cleaning cycle.

•Either way will pull the oil out of the pores...
-and will leave as natural of a finish as possible.

However:
•If pulling the parts is not feasible...
-Get a couple Mother's Polishing Balls; and:
-Both of their Aluminum and Billet Aluminum polishes.
-Polish out as much as you can:
*Sometimes that's the best that can safely be done
without parts removal.


Bob

 

[tuscarora dave]

•It looks like oils/contaminates have "soaked into"
the pores of the cast aluminum.

•The safest way I've found to "pull out" all of the oil
from the pores, is to put the parts in a heated ultrasonic-cleaner overnight.
-That...or put them in the oven for an overnight cleaning cycle.

•Either way will pull the oil out of the pores...
-and will leave as natural of a finish as possible.

However:
•If pulling the parts is not feasible...
-Get a couple Mother's Polishing Balls; and:
-Both of their Aluminum and Billet Aluminum polishes.
-Polish out as much as you can:
*Sometimes that's the best that can safely be done
without parts removal.


Bob

That's interesting Bob. You learn something new every day... What temperature would be a good place to do this?

 

[FUNX650]

That's interesting Bob. You learn something new every day... What temperature would be a good place to do this?

Dave...

If I do it in-house:
I use the oven's auto clean cyle:
I know that's above 500 F./Broil.

After the clean cycle:
I allow two to three hours of cool-down, before opening the oven door and removing parts.

Note:
I use a "containment-pan" while parts are cooking.

Bob

PS:
-I've found that this is one way to see if the Woman is really a keeper, or not.
-Oh yeah...that...And cleaning-out gas tanks in the bathtub!! LOL


Bob

 

[tuscarora dave]

Dave...

If I do it in-house:
I use the oven's auto clean cyle:
I know that's above 500 F./Broil.

After the clean cycle:
I allow two to three hours of cool-down, before opening the oven door and removing parts.

Note:
I use a "containment-pan" while parts are cooking.

Bob

Thanks for the info.

PS:
-I've found that this is one way to see if the Woman is really a keeper, or not.
-Oh yeah...that...And cleaning-out gas tanks in the bathtub!! LOL


Bob

Reminds me of something I did years ago.

I was doing a driveway repair, replacing a front wheel bearing in a Ford Tempo. I had no shop press at the time so after beating out the old bearing with a hammer and drift, I threw the steering knuckle in the oven at 350 degrees and placed the new bearing in the freezer. A few hours later I dropped the frozen wheel bearing into the heated steering knuckle and the entire house smelled like a transmission shop for the next week.

I guess she thought I was a keeper at the time, but I never did that again.

 

[SANTA3013]

Thanks for the input. I did let the product sit for a few minutes and then agitated with a parts cleaning brush. I may end up just removing the cover from the top of the engine. I think this is going to be the best way to ensure it gets clean.