salt in outboard motors

[VicS]

Just sold a merc that I used constantly for ten years & never flushed once.

Moral of this story: Dont buy a used outboard from kristifercolumnbus . ​

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[KristiferColumbus]

Moral of this story: Dont buy a used outboard from kristifercolumnbus . ​

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The purchaser seemed very happy no complaints
By the way I gave him some very good advice on how not to go wasting money on thermostats

 

[VicS]

The purchaser seemed very happy no complaints
By the way I gave him some very good advice on how not to go wasting money on thermostats

Very bad advice you mean.

 

[Gordonmc]

If you want to shift the deposit, use phosphoric acid, that really does work and aluminium phosphate is fairly stable (its the etching material used before painting an aluminium assembly) so it won't damage the aluminium engine castings.

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Charles_reed's advice is sound.
If you can get hold of it, Marine non-foaming toilet cleaner contains enough phosphoric acid to do the job in solution. I bought a couple of litres of NATO issue stuff from a market stall a few years ago and flush my Merc 2.2 occasionally. About a cupful in a half wheelie bin full of water.
It is also the best soak for really badly corroded bronze and brass.

 

[--ice--]

Hot water!
A couple of years ago I bought myself an Evinrude V4 90 iirc, got it very cheap as it had been poorly maintained and everytime it was out on the water the alarm sounded after a minute or so as it had over heating issues.
Pulling out the stats taught me that salt was more of a serious problem than I had ever imagined - I had always thought the flushing was overrated. I am not a time served or trained marine engineer but I do hold pieces of paper that say I know how to work on cars, and being quite technically minded I am not frightened to have a go.
Two stat's at £90 delivered and after watching mum putting salt in hot water gave me the idea of a wheely bin full of hot tap water and the engine was purring like a kitten, no alarms. The water was filthy I could taste the salt that had been dissolved from the water ways within the engine.

After seeing how serious salt can affect an outboard I have always tried to flush out an engine as best as possible.

 

[longjohnsilver]

Hadn't noticed the date but someone may still find the information useful as hopefully engines will last a long time.

Yes they do, my 2 hp Yam is still going strong on the odd occasions I use it! A fabulous little engine.

 

[steve66]

Hi Yes there is a flushing additive that removes salt deposits that doesnt damage impellers.I find it works well but only once the engine is stripped. Havent really persevered in using it with the engine built and complete.
http://www.mailspeedmarine.com/engine-accessories/starbrite/descaling-engine-flush739677.bhtml

 

[davey]

We have a Mariner 2 hp outboard, and I mentioned to my wife that there were several items in PBO about the problem of salt deposits in the cooling systems of small outboards, and the difficulty of removing them. There is a council of perfection that says you should run the motor in fresh water each time you run it in the sea, but I suspect that is more honoured in the breach than the observance, especially when returning to the mooring on a wet Sunday night.

Anyway, she said there are chemicals you can add to everything from kettles to toilets to remove limescale, and wasn't there something you could use in water every now and again to remove salt deposits from outboard's cooling systems? I don't know. Does anyone have any ideas?

One problem is that sea water is not just H2O and NaCl (water and sodium chloride) as there are other chemicals in it as well such as lime and chalk. One extremely useful but very dangerous chemical that can be used on cast iron engines (e.g. a British Seagull cylinder block) is HF (Hydrofluoric Acid) I saw an article in an American publication that was about a hundred years old and the writer eulogized over the stuff as "It will even dissolve sand cores left in the castings by the iron-founders" . Technically HF is classed as a weak acid unlike Nitric Acid or Sulphuric Acid so its action on metal is fairly mild. The downside to HF is that it goes hell for leather in its search for Calcium. Should one get it on ones skin it will go straight through and attack ones bones! The antidote is a calcium sugar which needs to be injected quickly. Most people won't want the hassle of needing rubber gloves, aprons, face masks and antidote syringes so Vinegar might be a better bet. In some countries one can buy preparations that contain HF in supermarkets and car accessory shops. It is marketed as Chrome Cleaner. Even though the HF content is small, rubber gloves and eye protection are still needed. A chemical that was used in my schooldays for cleaning glassware was Chromic Acid. This is fairly safe compared to Hydrofluoric Acid which one most definitely would not use for cleaning glass as it dissolves it! What one must never use on aluminium are alkaline substances as anything caustic will destroy the aluminium. On an old British Seagull the best way to clean the water passages is to remove the "Do Not Remove" plate so that the rust can be drilled away. Masonry bits are good for drilling through hardened layers of barnacled rust but on no account use a bit with a hexagon or an SDS shank. Instead use a drill bit that has a standard round shank and do not tighten the drill chuck too much as if the drill bit jams it is better for the chuck to slip. Of course modern cordless drills usually have a slip clutch which solves the problem. Shot-blasting is another way of getting rid of unwanted deposits but most machines do not have a small enough nozzle so other areas would get damaged. I do know a Yanmar IGM10 enthusiast and he likes to use vinegar followed by plain water followed by water containing anti-freeze. The remaining antifreeze eliminates the chance of the block cracking during winter.

 

[VicS]

One problem is.............

You are referring to a post which is now over 12 years old. Hopefully the OP has found the answer to his question by now.

HF , weak acid though it may be, is one of the most unpleasant and dangerous substances i have used on regular basis.

 

[AngusMcDoon]

It's like an old friend, this thread. Every few years it comes back.