Looking inside the intercooler of my '06 MINI Cooper S when I had it off recently, to replace the supercharger, I noticed that the inside was coated in a thin film of oil. This decreases the efficiency of the intercooler by fouling up the heat transfer between the intercooler fins and the air flowing through it.This is the solution I came up with.
Disclaimer: I don't know how your intercooling system works. This How To won't do damage to a first generation MINI Cooper if followed properly but there could be a slight difference in your system that could cause problems. It's unlikely but possible so read the Instructable and then make a decision based on your situation. It is also possible that the inside of your intercooler may never need cleaned. In Gen 1 MINI's the crankcase vents into the air system, which means oil vapor and mist gets into the air system, making a mess of things.
Step 1: Materials and Tools
- Acetone, 1 qt, $7 - Acetone evaporates quickly and is safe for the materials we will be using it on.
- Rubber Bands, x 2, Free - Look at the size of the openings on your intercooler and choose your bands accordingly. Heavy duty bands are best.
- Plastic Bags, x 2, Free - Try to find two without holes.
- Gloves - Make sure solvent won't dissolve them or soak through.
- Mask - Brain cells are good, acetone hates brain cells.
- Bucket - I used an oil pan already half full of junk coolent. Check all applicable local laws for disposal of used solvents.
Step 2: Prep and Safety
Now that you have the intercooler out it's time to get ready to clean. Go to a well ventilated area (outside) and get everything together. Now suit up! Ok, just gloves and a mask, and safety goggles if you plan on getting really crazy and flinging acetone all over the place.
Step 3: Seal the Unit
Stand the intercooler up on one end. Grab one of the plastic bags and spread it flat, it should be 2 layers thick everywhere. Now fold it at least once, depending on the size of the opening to be sealed. The sealing area needs to not only be as big as the opening but hang over the edge enough for the the rubber band to hold it. Which is the next step. Place the folded bag on the opening and stretch the rubber band around it. Be careful of making wrinkles in the plastic underneath the band, pull out any wrinkles that form.
Before moving on, fold the second bag so you are ready to seal the other end.
Step 4: Clean
After a couple of minutes of sloshing the solvent around, your seals will probably start to leak. At this point, or whenever you think you've cleaned long enough, with the unit over the bucket carefully remove whichever seal is leaking the worst and pour the used acetone into the bucket. You know it's been working because it goes in clear and comes out a sickly brown.
If the solvent you poured out was really dirty then pour a couple more splashes in and rinse it. I ended up rinsing mine 4-5 more times because it was so dirty. There is no need to re-seal the open end at this point if you are careful.
Step 5: Dry and Motor
Acetone evaporates pretty quickly but I might wait 12+ hours to put the unit back on since there are lots of little places for it to hide and I'm sure it isn't great for a engine. If you have compressed air, blowing it through will reduce the dry out time.
Once you're sure it's dry, reinstall and enjoy the, probably imperceptible, performance gain of cooler intake air.
Remember to properly dispose of the waste acetone and keep on Motoring!