Yellowed Radiator Expansion Bottle

[100 IAN]

How can I clean/return to white a very yellowed (almost brown) radiator expansion bottle?
Ideally I’d fit a new one (Audi / VW part number 811 121 407) but they’re NLA
Lots of YouTube videos but all have comments saying ‘tried this and it did absolutely nothing’.
Would be great to hear from anyone who’s had success with a particular method, or knows of a company who might have access to stronger chemicals and offers a professional service?
Presumably all the pro-restorers & concourse restorations must have a solution for this problem (?)

[itcaptainslow]

I've had success in the past removing the bottle, half filling with liquid brake cleaner & something (e.g. gravel/nuts/bolts) to agitate with, then shake like mad for as long as you can.

[Pica-Pica]

First thing is to ask is why and how is it discoloured. Is it surface contamination or the plastic degrading?

[Belle427]

I've tried most things but once the plastic is discoloured it's time for a new one.

[julianm]

Might be worth having a try with strong hydrogen peroxide - hair salon stuff. It helps if the part is in bright sunlight. It's a method used by collectors to restore old plastic parts on the likes of 70's games comsoles.

http://www.retrofixes.com/2013/10/how-to-clean-whi...