Muriatic Acid to clean water passages

[wjob]

On my '88 DT 150hp Suzuki has been suggested that I should try some straight muriatic acid through the thermostat hole to clean out crud in the cooling passages, followed by a quick flush. Comments please and any suggestions on exact procedure. Might make sense to drop lower unit first so as not to expose impellar to the acid and maybe I should dilute acid first?

Idea is to go this route first, before pulling heads?

 

[JUSTINTIME]

Re: Muriatic Acid to clean water passages

use vinegar is much safer
even salt-a-way is better also

 

[yamamarinetech40]

Re: Muriatic Acid to clean water passages

Have had great results with Neutra-Salt, you can buy at most dealers of Mercruiser and Volvo(is a Volvo product), can be left in overnight or longer, so won't eat up water pump, etc.

 

[wjob]

Re: Muriatic Acid to clean water passages

Thanks for info. Am I correct to put it in through the thermostat opening or is there another place that doesn't even require pulling the thermostat?

 

[WillyBWright]

Re: Muriatic Acid to clean water passages

That would be the easiest most accessible location. Muriatic is mostly HydroChloric acid which eats aluminum. Don't use that. Farm supply stores have Acid wash or Milkstone remover. Both are Phosphoric acid and much less harsh on aluminum. That works well with scale, not sure how it would do with salt. Saltwater-specific products would probably be better for that.

You're probably going to loosen chunks, so rather than backflushing through the thermostat holes first, run the motor on muffs first to flush what you can out of those holes. Then backflush, run the motor on muffs again, put things back together, and go have fun.