DIY: Aluminum Case and Transmission Cleaning
Before the engine teardown, I decided to tackle cleaning the aluminum transmission case. Im going to show you how I did it.
Note: The following information is for educational use only. Before proceeding please read my disclaimer page.
Note: This post contains links to Amazon products and other trusted Porsche parts vendors. As an Amazon Associate I earn from qualifying purchases.
This thing was disgusting and I knew it was going to sit on my garage floor and get pushed around from place to place. The least I could do was clean it so it wouldn’t get my shoes dirty every time I tripped over it.
This is the single dirtiest car part I have ever cleaned. It was covered in engine oil, sticky transmission fluid, and super sticky CV joint grease. Here is my method for successfully cleaning this worst case condition.
Warning: this was the best method for me but please follow all safety precautions listed on all the cleaning products and equipment you use.
Materials & Equipment
- Steam cleaner (I recommend the McCulloch MC1275)
- At least 1 gallon of concentrated biodegradable degreaser such as Simple Green or Purple Power
- A small bottle of concentrated dishwashing detergent such as Dawn
- A spray bottle
- A bucket you are willing to get permanently dirty
- A shop rag or two or several
- An assortment of brushes (heavy duty nylon, some brass, maybe even steel) in different shapes. Old toothbrushes, big scrubbing brushes with handles, and some round gun bore brushes.
- An assortment of plastic scrapers are a big help but not mandatory (no metal scrapers)
- An oil drain pan or two
- A box of chemical resistant rubber gloves (I highly recommend heavy duty black nitrile ones)
- Safety glasses (mandatory)
- Work clothes consisting of pants and long sleeves (degreaser could irritate your bare skin)
Procedure for Cleaning Bare Aluminum Surface
- Put on safety glasses, gloves, and work clothes.
- Squeeze some dishwashing detergent in the sacrificial bucket and fill it 2/3 full of water; room temp is ok but the warmer the better.
- Fill steam cleaner with clean water in the reservoir, turn it on, and let it warm up.
- Fill spray bottle with undiluted degreaser.
- Visually separate the overall area you are going to clean into smaller manageable sections.
- You will pick a small section to start on first and don’t move to the next section until it is clean.
- This is important because sometimes cleaning moves slowly and it is hard to see immediate progress.
- Place oil drain pan under the area you will clean.
- When the steam cleaner is warmed up, spray the area to be cleaned with hot steam for a few seconds. This will soften the grime. Careful, the steam is steaming hot!
- If the grease buildup is thick, use plastic scrapers to physically scrape off as much loose grime as possible and let it fall into the oil drain pan.
- Spray the area again with steam to soften the remaining grime stuck to the surface.
- Spray the area with degreaser from spray bottle.
- Scrub the area with brushes. If the brush loads up with grease, dip it in the bucket and shake it around to rinse off as much as you can. Use big brushes for large flat areas and small brushes for nooks and crannies.
- Spray the area with steam to rinse and re-soften remaining grime.
- Repeat steps 9-12 until most of the grime is removed.
- When there is a thin film of grease left on the surface, switch from the brushes to the shop rag.
- Repeat steps 9 and 10 and then scrub the area with the shop rag. When the rag loads up with grease, dip it in the bucket, and squeeze it out in the water, then lift out and wring as much of the water as you can.
- Repeat steps 9, 10, and 15 and the surface will very gradually look like new again.
- You may have some nooks and crannies where grime refuses to come out. This is where you grab the round brushes and use the end to gently get in there and scrape/pick the gunk out.
- Keep an eye on your gloves as they could tear or develop holes as they get banged up. If they tear, wash your hands and change them immediately as the degreaser could irritate your skin.
- Once the small section you have been working on is spotless, move onto the next section and repeat entire procedure until every surface is clean.
You will see a gradual improvement as the transmission surfaces get cleaner and the water in the bucket gets dirtier:
After lots of elbow grease, time, and patience your transmission case will look like this:
Now you can spot leaks very easily on the clean surface.
Note: Some degreasers will attack bare aluminum and painted surfaces if you allow them to sit on the surface for a long time. I have had a spray bottle leak Purple Power degreaser onto a metal cabinet shelf and take the paint off overnight. I would not leave it on the surface for more than half a minute. Don’t saturate a surface in degreaser and walk away from it for the night. Rinse with steam and wipe off with rinsed rag and it should be fine.
Enjoy your newly cleaned transmission and fix those damn leaks before they get out of hand again.