This is to share the results of a little experiment. Backstory; my 99' Honda 50 has lots of hours and gets year round use in salt. It has built up enough crumbs of sediment that the pee tube frequently gets clogged and the stream slows to a dribble or stops. The rest of the motor is flowing fine as I've never yet hear the overheat alarm, and it gets run hard often. So after some research I wanted to give a descaling rise a try, and the Rydlyme brand seemed to be a reasonably safe bet. The chemistry that acids readily dissolve salt deposits is proven, but acids also dissolve metals like Aluminum. Acids can be buffered, which means they add something to it to make it less reactive with metals which is what I think they've done with products like Rydlyme, but there's still some risk depending on the alloy, from what I understand.
Long story short; it absolutely removed salt buildup and a ton more of what looks like sand than I was expecting, but the pee tube is still clogging. I think I chickened out and stopped it too soon, I'm debating on doing it again. While it was running you could smell the gas from the reaction and I stopped and checked the thermostat area at around 20 minutes and it was clean down to the metal so that's when I decided to cut it short for fear of the chemical also eating the metal, and maybe I didn't let it go long enough to completely dissolve the crumbs that are clogging the pee tube. But here's the results. I have some before pictures of the water jackets under the intake manifold from last year, but I haven't taken it apart yet for the after pictures of that section. I'll come back and post those next time I have a need to remove the intake manifold (too busy to do it just for pictures).
Procedure: Remove lower unit and thermostat, use an old bilge pump connected to the water pickup. I circulated some plain water as a test and got a few tiny grains of sand out but nothing of note. Then I mixed approximately 50% Rydlyme / 50% water and ran that through. You could smell the gas from the reaction. I mistakenly assumed that everything would be dissolved by the Rydlyme so I didn't think to look at the bottom of the bucket and just dumped it (the chemical is dark and you cannot see through it), but after I dumped the bucket there was a lot of what looked like beach sand left in the bucket. I'm going to guess there was a couple tablespoons of this stuff, so it most definitely loosened up a lot of stuff that plain water didn't remove.
Thermostat area before:
During, using an old bilge pump connected to the water feed tube and a bigger hose to direct the pee stream back into the bucket.
Thermostat area after:
What just happened to be stuck to the bottom of the bucket after I dumped it, a lot more got dumped out with the liquid:
Long story short; it absolutely removed salt buildup and a ton more of what looks like sand than I was expecting, but the pee tube is still clogging. I think I chickened out and stopped it too soon, I'm debating on doing it again. While it was running you could smell the gas from the reaction and I stopped and checked the thermostat area at around 20 minutes and it was clean down to the metal so that's when I decided to cut it short for fear of the chemical also eating the metal, and maybe I didn't let it go long enough to completely dissolve the crumbs that are clogging the pee tube. But here's the results. I have some before pictures of the water jackets under the intake manifold from last year, but I haven't taken it apart yet for the after pictures of that section. I'll come back and post those next time I have a need to remove the intake manifold (too busy to do it just for pictures).
Procedure: Remove lower unit and thermostat, use an old bilge pump connected to the water pickup. I circulated some plain water as a test and got a few tiny grains of sand out but nothing of note. Then I mixed approximately 50% Rydlyme / 50% water and ran that through. You could smell the gas from the reaction. I mistakenly assumed that everything would be dissolved by the Rydlyme so I didn't think to look at the bottom of the bucket and just dumped it (the chemical is dark and you cannot see through it), but after I dumped the bucket there was a lot of what looked like beach sand left in the bucket. I'm going to guess there was a couple tablespoons of this stuff, so it most definitely loosened up a lot of stuff that plain water didn't remove.
Thermostat area before:
During, using an old bilge pump connected to the water feed tube and a bigger hose to direct the pee stream back into the bucket.
Thermostat area after:
What just happened to be stuck to the bottom of the bucket after I dumped it, a lot more got dumped out with the liquid:
