My coolant overflow tank was sitting in my car for far too long and it was simply horrible. With a ton of 30 year old sludge, dirt, discoloration and anything else you can imagine. Good quality replacement coolant tanks for my car (1987 MR2 mk1 AW11) don’t exist, and used ones are usually in similar condition.
So I did some research to see how best to clean it and get it looking like new again.
Cleaning the inside was fairly easy with some common household items. Some rice, some bleach and a dish washing tab and a lot of shaking gave results that are were even better then I hoped. The outside was scrubbed with a dish washing pad and a bleach and water mixture. Again the results were very decent and 30 years worth of dirt was gone in mere minutes.
What was annoying me most of all and where it was the hardest to get the results was the yellowness of the coolant tank. Scrubbing is dead useless here, since the yellowness you can see on coolant tanks is the result of a chemical reaction. The only solution is to whiten/ bleach out the ugly yellow color out of the coolant overflow tank. However this is a lot easier said than done.
My initial research led me to a solution called Retrobright which was developed to get the yellowness out of old pcs like ataris and commodores. I made it and tried it, but the results were extremely poor. However I learned from Retrobright about the key ingredient to get my coolant overflow tank white again, and the magic ingredient is called hydrogen peroxide. The product with the highest concentration of hydrogen peroxide I could find was in hair-care products for bleaching your hair. On the same isle I found another product which promised to add an extra kick of aggressiveness into my bleaching formula, it was called bleaching powder and when mixed with the hydrogen cream it promised extra bleaching power. I stocked up and got to work. Results finally started to appear. After several bleaching sessions with the inside and outside of the coolant tank covered in the bleaching solution I managed to get most of the yellow color out. Mind you I couldn’t get every last shade out of it, but I did manage to get it looking A LOT better than it was when I started.
Here’s a little before and after pic: