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Old 09 September 2016, 04:13   #21
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I'd be worried about flushing an aggressive acid through an aluminium engine. The main constituent of brick acid is hydrochloric acid, mix that with ally & you end up with lots of hydrogen, water & salt. It might be something I'd consider if I had a problem, but not as a routine treatment.
Just IMHO of course


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me too reading the corrosion stuff i would think the internals of the engine are chromium oxide coated too that might be compromised with the brick acid not worth the risk at those hours OMO
not seen Suzuki advertising any cleaner either might be wrong
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Old 09 September 2016, 04:19   #22
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Yup, iirc brick acid has dire warnings on the container about not letting it near ally/zinc etc. We used to use it for cleaning marine growth off diving spidge, if you left it too long it would de-zinc brass & pit bronze.


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Old 09 September 2016, 05:54   #23
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Yes. These are my thoughts regarding all of the marine descalers. They all contain hydrochloric acid which is brick acid. I've witnessed myself what this does to certain metals.
I'm now starting to think of using powdered descaler which is citric acid. Is this what dishwasher descaler is? It's cheap enough that I could just dump it in to my flushing drum and run up for 5 or 10 min at a time.
Any thoughts?
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Old 09 September 2016, 06:04   #24
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Yes. These are my thoughts regarding all of the marine descalers. They all contain hydrochloric acid which is brick acid. I've witnessed myself what this does to certain metals.
I'm now starting to think of using powdered descaler which is citric acid. Is this what dishwasher descaler is? It's cheap enough that I could just dump it in to my flushing drum and run up for 5 or 10 min at a time.
Any thoughts?

I use citric acid in the ultrasonic bath for cleaning diving kit, even that will strip chrome & pit brass if left too long. At the end of the day, aluminium is a reactive metal that doesn't get along with acids. Personally I wouldn't be giving my pride & joy an acid enema that could potentially rot it from the inside out. You aren't solving the problem, just replacing it with another. I have had boats for 30 years & never had the need to resort to such measures. All my engines have been thoroughly flushed after each use & I've never had a problem. Prevention is better than cure as they say😏

All IMHO of course.


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Old 09 September 2016, 06:55   #25
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Pikey Dave - I think I need to get the bottom leg off, remove the stat and anode covers myself and see just what the guy who serviced it meant by "excessive corrosion"
I maybe being paranoid!?!
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Old 09 September 2016, 07:19   #26
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Had a similar issue with our honda 90. Turned out because it hadn't been used the impeller had lost it spring. Might b worth checking.
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Old 09 September 2016, 08:22   #27
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So I've been reading up on this quite a bit and the answer is not clear cut. Remember we're flushing an item that has Stainless and aluminum (various types).

I now understand why the prescribed engine flushers/cleaners are so expensive.

There are all types of acids that can be used to descale and clean however certain acids are bad for stainless, copper, rubber and certain types of aluminum. Heat can also greatly effect the corrosion effect to these metals, the higher the temp the more prone you are (exponentially); so be careful how hot of a solution your using. Because citric acid is of high ionisation, it can be used at room temperature for chelating with great effect.
Organic acids are used when there is a probability of corrosion damage by a mineral acid. Organic acids are much more expensive and need to be used at a higher temperature.

Supposedly when using citric acid (low pH) on aluminum your suppose to also use some ammonia (inhibitor) with it to reduce the effect of corrosion to the aluminum. Then your suppose to be passifying with alkali (higher pH) to form an oxide layer on the metal, coating the aluminum to protect it from further corrosion.

Any of the above mentioned will eat zinc quite quickly.

I did read that scaling adhered to metal needing cooling greatly reduces the cooling effect by as much as 20% so your more prone to overheating if you have bad scaling.

These are just notes and an example of why it's more complicated than just adding some cheap citric acid and water as a simple cleaning solution and that it may not be the answer.

I think the best answer to finding what is best for your engine flushing/cleaning is the one given by the engine manufacturer.
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Old 09 September 2016, 09:30   #28
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So I've been reading up on this quite a bit and the answer is not clear cut. Remember we're flushing an item that has Stainless and aluminum (various types).



I now understand why the prescribed engine flushers/cleaners are so expensive.



There are all types of acids that can be used to descale and clean however certain acids are bad for stainless, copper, rubber and certain types of aluminum. Heat can also greatly effect the corrosion effect to these metals, the higher the temp the more prone you are (exponentially); so be careful how hot of a solution your using. Because citric acid is of high ionisation, it can be used at room temperature for chelating with great effect.

Organic acids are used when there is a probability of corrosion damage by a mineral acid. Organic acids are much more expensive and need to be used at a higher temperature.



Supposedly when using citric acid (low pH) on aluminum your suppose to also use some ammonia (inhibitor) with it to reduce the effect of corrosion to the aluminum. Then your suppose to be passifying with alkali (higher pH) to form an oxide layer on the metal, coating the aluminum to protect it from further corrosion.



Any of the above mentioned will eat zinc quite quickly.



I did read that scaling adhered to metal needing cooling greatly reduces the cooling effect by as much as 20% so your more prone to overheating if you have bad scaling.



These are just notes and an example of why it's more complicated than just adding some cheap citric acid and water as a simple cleaning solution and that it may not be the answer.



I think the best answer to finding what is best for your engine flushing/cleaning is the one given by the engine manufacturer.

So that'll be a no then😉


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Old 09 September 2016, 12:25   #29
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R18628 - thanks for tip but I don't think it's that as the impeller is changed annually and this week was its first outing since service and impeller change in March.

I've just cleared out the tube to the telltale and got a few tiny crumbs of debris out (probably scrapings from the guy who last serviced it).
Telltale now normal.

Been chatting to a marine engineer today who has never used anything for flushing other than fresh water.
His thinking (and he's probably right!)
Is to use the motor, enjoy your boating, flush it after each use, stick to the service regime, and accept that nothing dipped in water, least of all salt water, will last forever!
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Old 09 September 2016, 13:43   #30
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So that'll be a no then��


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Not necessarily as I don't know the correct answer but having more knowledge of the effects of these cleaners can help you determine if needed or not and which one to choose.

I don't know what the formula is for Rydlyme and other similar products but they could have added a cocktail of different stuff that will clean out your engine properly while at the same time protect the motor. Maybe they're using organic acids which will explain the high price.

Citric acid in low levels and short time spans could be fine but it can most definitely corrode the metals in your engine if not done correctly. The cleaners with citric acid with the right additives can be used more heavily than just citric acid. We also don't know what are the metals are in the engine exposed to the cleaners. Remember that good aluminum has added metals inside it (zinc-magnesium, copper, scandium) to make them stronger and those metals are the concern.

This type of cleaner is actually a huge business in other massive industries like the food industry so there are companies that are fully dedicated to coming up with formulas to cleaning out equipment and scaling without damaging it.

Another thing to think about while using one of these cleaners in your engine. In the unfortunate environment we live and boating in is that there's oil in the sea water especially in harbors, these attach and coat the engine on the outside and inside. The cleaners, like citric acid does not do well cleaning the meta scalingl with oils coating them. It's always best to remove the oily film prior to using your expensive descaling cleaners. Maybe flush the engine with some dishwashing soap first to help remove the oils. It's just an idea. I know I must use a degreaser before using a acid wash to remove corrosion on greasy used tools and parts.

I will say there is a good purpose for these cleaners and descales like Rydlyme. For instance when you buy a used engine and you suspect the previous owner did not flush the engine properly. Also, just flushing it with fresh water will not take care of everything. If the water in the engine is exposed to hot temperatures then you will get scaling deposits just like a hot water heater collects deposits. All the fresh water flushing will not remove or dissolve heat-hardened scaling.
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