Cocking about trying to clean an expansion tank

[Stretch]

G'day Folks,

I've been messing about with a little experiment trying to clean out gunk from an expansion tank. The gunk came from a failed head gasket - and then there's the age yellowing that probably will never go...

...so far it is a list of what doesn't work and one thing (so far) that has given the best results.

I started off with baking soda - forgot to mention this the first time I posted...

...sorry no pictures - it didn't work...

...Then I tried vinegar (hey it is pretty good at cleaning burnt off crud on saucepans!)



Unfortunately I only had red wine vinegar.

It managed to stain the inside a bit more.



So OK after that I thought - engine degreaser



It works well on mucky engines

Not so good inside grotty expansion tanks though



(It looked like the red wine vinegar staining was planning to stay)