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Acid washing the cooling system in a marine engine

I have a marine engine that could have rust clogging the cooling ports in the block. Could I use muriatic acid [affil links] as a flush to clean the block? If so, should I use it full strength or diluted? How many minutes would you recommend that I allow it to work before flushing with fresh water?

Thanks,

Gil Seigler
- Richmond, Virginia
2002

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2002

Hi Gil,

I see that no one else had replied.... so here's my reply but then I sure ain't no chemist.

Firstly you did NOT indicate whether your engine is running ie. cooling using salt water, i.e., brine or is a closed system using clean(ish) water.

Ah, salt is sodium chloride and muriatic acid, ie. Hydrochloric, is HCl. Hence I don't think that it would work too well for you. Use sulfuric. But for clean water it should be OK.

Use 50% concentration...but then if you buy muriatic it is probably diluted somewhat anyhow. Run for an hour, ie. pump it around for an hour. Then discard after NEUTRALIZING with baking soda [on eBay or Amazon] first of all. See # 12461 and # 12044, too.

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).