'87 Johnson 70 Rebuild Questions

[ddcarter3]

I just received the used head. It is an aluminium head. It has oxidation all over. Looking past that it looks to be in good shape. My Dad has some Sodium Hydroxide (a cuastic). Can we use that to soak the aluminium head in to clean it? If so, how long?

 

[iwombat]

Re: '87 Johnson 70 Rebuild Questions

Woa! Careful there. While it's true that the Sodium Hydroxide will put the Aluminum Oxide into solution, it's also true that the H2O suspending the NaOH will also oxidize the Aluminum. What you'll have is a two part reaction and will probably cause even more pitting than you have already before the oxide gets disolved.

2Al + 6H2O --> 2 Al(OH)3 + 3H

Al(OH)3 + NaOH --> (Na+) + [Al(OH)4]-

I think I'd try another route.

 

[R.Johnson]

Re: '87 Johnson 70 Rebuild Questions

If the gasket surface's are in good shape, that oxidation won't hurt any thing.

 

[ddcarter3]

Re: '87 Johnson 70 Rebuild Questions

iwombat,
Thanks for the chemistry lesson. I forwarded this to Dad. He understands chemistry. I just get that glazed look on my face. Dad's question is what should we use to clean the head? Also, the water jackets have what looks like CaCl inside. Thanks for your help.

 

[R.Johnson]

Re: '87 Johnson 70 Rebuild Questions

White vinegar will take that off.

 

[iwombat]

Re: '87 Johnson 70 Rebuild Questions

No problems, sodium hydroxide and aluminum is a classic chem 101 two part reaction demonstration. I just happend to remember it from the distant past.

You can remove most of that scale with a wire brush and soapy water. A white vinegar flush and a small flexible round brush will clear out those water passages. Aluminum Oxide is fine everywhere but the gasket surface (even there a fine film protects the Aluminum).

 

[ddcarter3]

Re: '87 Johnson 70 Rebuild Questions

Done deal....thanks