Question about using Rydlyme to desalt outboard water jacket

[Jcorstorphine]

I have set up a circulation system to pump a 50% solution of Rydlyme solution through the water jackets of my 2.5 HP outboard using a small submersible pump attached to the inlet cooling pipe (with the lower leg removed). See this video.

https://flic.kr/p/U1RGJK

My question is how long to keep running the solution as after about an hour it is still fizzing away.and if I drop some solution onto the concrete, it is still pretty reactive. My worry is that I damage the water jackets as some references would suggest that after only about 15 mins the reaction stops.

 

[VicS]

I have set up a circulation system to pump a 50% solution of Rydlyme solution through the water jackets of my 2.5 HP

My question is how long to keep running the solution as after about an hour it is still fizzing away.

Rydlyme suggest 25 -45 minutes: http://www.rydlymemarine.com/assets/1/7/Outboard_descaling_instructions.pdf

 

[Jcorstorphine]

Rydlyme suggest 25 -45 minutes: http://www.rydlymemarine.com/assets/1/7/Outboard_descaling_instructions.pdf

Thanks Vic, problem is that the instructions suggest that the reaction will be completed within the 45mins but in my case it is still going strong. Do you think there is any concern over the solution eating away the aluminium castings. I am not sure what is reacting is it salt or aluminium chloride or aluminium alloy.

HCl + NaCl = ? or HCl + AlCl = ? or HCl + Al = ?

Over 50 years since I did Chemistry, hence further question.

 

[VicS]

Thanks Vic, problem is that the instructions suggest that the reaction will be completed within the 45mins but in my case it is still going strong. Do you think there is any concern over the solution eating away the aluminium castings. I am not sure what is reacting is it salt or aluminium chloride or aluminium alloy.

HCl + NaCl = ? or HCl + AlCl = ? or HCl + Al = ?

Over 50 years since I did Chemistry, hence further question.

Hopefully it is just reacting with the carbonate scale.

 

[thinwater]

I recently did an article for Practical Sailor researching corrosion rates of adjacent metals vs. scale removal rate (not yet published). Unsurprisingly, some acids are better for some metals than others. And while Rydlyme is a good choice for steel, CLR is a much better choice for aluminum 4x less corrosion for the same scale removal).

 

[Ian_Rob]

Be very careful. I cleaned my Volvo Prop 4 weeks ago in Rydlyme not realising that the core of the hub is aluminium and damaged it within 90 mins to the point I needed to buy a replacement hub.

PS Rydlyme and aluminium do not mix.

 

[Gin]

I recently did an article for Practical Sailor researching corrosion rates of adjacent metals vs. scale removal rate (not yet published). Unsurprisingly, some acids are better for some metals than others. And while Rydlyme is a good choice for steel, CLR is a much better choice for aluminum 4x less corrosion for the same scale removal).

I liked the idea of CLR for my outboards, but one of them at least has an aluminium/ alloy head, so I took a look at the manufacturers site, and they say do not use on aluminium- perhaps a very diluted mix would be safe?

http://www.thecarycompany.com/facility-supplies/cleaners/clr/faq

 

[thinwater]

I liked the idea of CLR for my outboards, but one of them at least has an aluminium/ alloy head, so I took a look at the manufacturers site, and they say do not use on aluminium- perhaps a very diluted mix would be safe?

http://www.thecarycompany.com/facility-supplies/cleaners/clr/faq

ALL acid cleaners, including vinegar (actually one of the worst Al corrosion to scale removal ratios) represent some risk for aluminum, and how vendors chose to relate that risk depends on the legal and marketing departments. The trick is the correct timing. CLR was about 0.01 mils/hour, and about 2-3 hours are required at a 10:1 dilution, depending on the extent of scale build-up. Also remember that some additional scale will break free and fall off over time.

Yes, the recomended dilution is "relatively" safe.

 

[Ian_Rob]

Whilst 25- 45minutes at the recommended concentration might be ok for one treatment will not successive treatments just compound the erosion and in that sense there isn't a safe concentration?

 

[Jcorstorphine]

Be very careful. I cleaned my Volvo Prop 4 weeks ago in Rydlyme not realising that the core of the hub is aluminium and damaged it within 90 mins to the point I needed to buy a replacement hub.

PS Rydlyme and aluminium do not mix.

I am a bit hacked off about using Rydlyme as it claims to be a safe biodegradable solution for cleaning outboards, it also claims to be totally safe to use. Well, I am not sure about it being safe as it is basically 10% Hydrochloric Acid which is about a third of the strength of industrial HCl and reacts vigorously with concrete.
When I set up the circulation system, I printed off the MSDS sheet, wore overalls and used eye protection. Even with this I got a few splashes on my face with which stung a bit so think they should revise their claims about it being safe to use and suitable for cleaning aluminium outboards in the light of some of the responses to my original post.

 

[vyv_cox]

I recently did an article for Practical Sailor researching corrosion rates of adjacent metals vs. scale removal rate (not yet published). Unsurprisingly, some acids are better for some metals than others. And while Rydlyme is a good choice for steel, CLR is a much better choice for aluminum 4x less corrosion for the same scale removal).

Can I ask what grade of aluminium you used? I cannot claim to have carried out extensive research but in my tests the strip and sheet sold by DIY outlets, which is normally ductile 99.9% pure aluminium, reacted quite strongly with HCl. Good quality marine grade alloy in the 5xxx series, containing 5% magnesium plus small amounts of iron, copper, silicon, manganese, was far less reactive. This photo shows a masthead antenna bracket in 5086 with a stainless steel fitting and typical carbonate deposits being cleaned up using 6% w/w HCl. The carbonate is fizzing nicely but the metal parts were unaffected in half an hour or so.

 

[thinwater]

Can I ask what grade of aluminium you used? I cannot claim to have carried out extensive research but in my tests the strip and sheet sold by DIY outlets, which is normally ductile 99.9% pure aluminium, reacted quite strongly with HCl. Good quality marine grade alloy in the 5xxx series, containing 5% magnesium plus small amounts of iron, copper, silicon, manganese, was far less reactive. This photo shows a masthead antenna bracket in 5086 with a stainless steel fitting and typical carbonate deposits being cleaned up using 6% w/w HCl. The carbonate is fizzing nicely but the metal parts were unaffected in half an hour or so.

You are correct, with pure Al the difference is greater. I picked an alloy several US outboard vendors suggested was fair (Merc, Johnson), since I knew guys in those engineering departments. I have been active on ASTM engine coolant corrosion development committees for many years. I'm more of a novice re. outboards. This was more of a hobby project, but I believe the trend is probably valid.

UNS A23190 (SAE 329). It is a common die casting alloy.

Aluminum, Al 84.8 - 91.4 % As remainder
Copper, Cu 3.0 - 4.0 %
Iron, Fe <= 1.2 %
Magnesium, Mg 0.10 - 0.50 %
Manganese, Mn <= 0.80 %
Nickel, Ni <= 0.50 %
Other, total <= 0.50 %
Silicon, Si 5.5 - 6.5 %
Titanium, Ti <= 0.25 %
Zinc, Zn <= 1.0 %