Comments on: Why is it an outboard can circulate raw salt water but we cannot through aluminum automotive engines?

By: Boatman

Boatman — Thu, 21 Jan 2010 07:10:51 +0000

Outboard engine blocks are treated with a chromate conversion process, inside and out, to help protect the material in the water jackets. This is costly, and not done on automotive blocks. Since I/O manufacturers buy blocks from auto companies, they are fairly standard to cars. Outboards also have zinc anodes on them to sacrifice themselves in place of the aluminum. And finally, yes, the alloys are more expensive in marine applications. You won’t find any raw carbon steel fasteners either - they’re all stainless, brass, or coated steel. All in all, the ability to withstand salt water costs a lot, and it’s not something people would be willing to pay for in a car, hence an I/O engine won’t have them either. Boatman

By: 45 cal

45 cal — Wed, 20 Jan 2010 11:25:58 +0000

Temp over 150 deg cause salt to deposit> And in a closed system at 200 degs salt would corrode all parts> so it wouldn’t work for a extended time of use>There are so many kinds of different metal in inboard that they start to corrode the second they are use in salt water> 45 cal

By: formersalt

formersalt — Tue, 19 Jan 2010 11:48:01 +0000

Outboards have a continual flow of cool water which is then discharged. In the process, salt will accumulate and, if not taken care of with fresh water flushes, block the water passages.
An auto cooling system is a closed system. The salt would solidify and block the passages rather quickly. formersalt