cooling passages blocked

[alapmac]

My cooling passages on an old 2hp Mariner outboard are blocked.
I have stripped everything down but cannot clear the deposits around the cylinder cooling channels.
Currently I have filled the channels with water but not much happening.
Is there a chemical solution which will disolve the salty/lime deposits?

 

[David2452]

Muriatic acid (32% Hydrocloric acid) available at most good plumbing shops, get a good pair of rubber gloves and goggles whilst you are there. Either soak the small parts in a PLASTIC bowl or pour into the passages.

Take care !!!
David

 

[NigelAmes]

I had a similar problem with a Suzuki 3.5. I used a strip of copper, so as not to damage the alluminium and spent hours gently rubbing away at the salt deposits. When I had cleared as much as I could I them filled a dustbin with hot fresh-water and ran the engine in that. I don't know whether the dustbin helped but the engine has given me no trouble since.

 

[TonyR]

For a slightly less dangerous option, try brick cleaner from B&Q

 

[Twister_Ken]

Or kettle/steam iron descaler