Join Date: Feb 2010
Location: Narragansett Bay
Thanked 593 Times in 569 Posts
Rep Power: 12
Re: Yanmar 3GMD: Rydlyme or other marine descaler in older engine
I would guess you're looking at salt water scale, not zinc oxide.
Rydlyme is great stuff. You need to fashion a way to fully recirculate the product for a period of time. That may require pulling the thermostat and/or impeller. It depends on where you plan to enter/exit.
It was so effective on mine several years back that the scale clogged the pump. A filter of some kind would be a good idea, even if just a strainer than return fluid dumped through.
The exterior corrosion appears to be from leakage, so I'd try to seal those back up again. I can't tell from the pics, but if the paint had been compromised in those locations, they may simply be exterior corrosion.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
In the harsh marine environment, something is always in need of repair. Margaritas fix everything.