Cleaning out cooling system on aluminum outboards

[zul8tr]

This is for a 1973 25ss engine I am working for some PM. Any recommendations on cleaning the coating that builds up on the cooling system aluminum surfaces around the cylinderes and adjacent areas:eek:. I have done easy to reach areas with a fine wire wheel on a variable speed drill and plan on getting a pencil shaped wire on the drill for other harder to reach areas. But is there a better way to get at the hard to reach areas, like a liquid cleaner of some type? A friend mentioned Corrosion X spray.

[88workcar]

I use muratic acid. It turns yellow and bubbles all over, smokes too. The you rinse it off with water.

[zul8tr]

I use muratic acid. It turns yellow and bubbles all over, smokes too. The you rinse it off with water.

Full strength :eek: or dilute (how much?) from the bottle the pool store sells?
I will test a small area.

[88workcar]

I get it at ace hardware, full strength. I do the blocks too if they are bad. It is easy to use and works wonders.

[David Mason]

In the Pro Division (Alky) it is the method used to clean the aluminum from the cyl walls. Used a swab and dipped it in the Muratic Acid and swab the cylinder while Dad changed out the piston. Once you did a few it was a 5 minute job.

Bought at local hardware store. I think even Lowes sells it.

[zul8tr]

I used the Muratic acid and it did a nice job, thanks for the tip.

Is there any protective coating recommended to seal the alum that will not effect the cooling heat transfer?