1999 johnson/tohatsu not cooling

[Refueler]

For descaling equipment use a 10% solution. Sulphamic acid is safe for steel, iron, glass and wood equipment, and may be used with caution on copper, aluminium, and galvanized metal surfaces. Clean in a soak tank or by circulation. For surfaces, apply to surface using a cloth or brush and allow to work for a few minutes. Agitate with brush if necessary and rinse thoroughly with clean water.

That is from the link post #20 ...

The mention not to use on such metals is in the higher concentrates in the next paragraph of the sheet ... it also gives clear indication of a neutralizer ... if you are so worried about using it.

As I say it was a commonly used method before ... but we always ran the motor after in a bin of clean fresh water ...

 

[Refueler]

Of course there's always Vinegar ......

 

[VicS]

a useful guide to using sulphamic acid - Sulphamic Acid (Sulfamic) - Descaler / Rust Remover
The guide does say not to use it on aluminium,zinc or galvanised metals.

A few sentences earlier it says , " may be used with caution on copper, aluminium, and galvanized metal surfaces.

 

[Refueler]

A few sentences earlier it says , " may be used with caution on copper, aluminium, and galvanized metal surfaces.

Thank you ... see the quote in my post #21

I'm sure if a search is made - a descaler 'safe' for aluminium etc. can be found ...

I won't name the outboard service people - but I can say honestly that a container of Fernox was definitely on their bench for use when I used to take outboards for service .... of course they had a big test tank as well for 'after run' ....

 

[Refueler]

Selalite Liquid Descaler Cleaner (Aluminium Safe) For Equipment/Tanks etc. in 5ltr Container: Amazon.co.uk: Kitchen & Home

just an example ...