Descaling KAD44 Is this OK?

joae

joae

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This summer I had some elevated temps on the port engine.
Decided to remove the aftercooler and heatexchanger for inspection and cleaning.
Here is a link to the video of the inspection before any cleaning.
https://youtu.be/N93pTnTP5rU

After this i decided to descale both heat exchangers with oxalic acid which seems quite common in the marine industry. I mixed around 100 grams per litre of the oxalic "powder". Mixture was about 30-40 deg C.

There was no noticeable effect when I poured it in and let the mix work for about 2 hours and think that nothing really happened except that it is very green in color.

The scale is still there.
Should i leave it in longer or how do I get it cleaner?

See picture below for the result after cleaning.
ZeqZrTpFvH78MCKb9
 
Never heard of using oxalic acid on anything other than gelcoat cleaning, the much favoured Y10 gel. Most people I have heard including myself use Rydlyme and pump it round the entire circuit for 4 hours - from the exhaust elbow inlet back through to impeller basket outlet . See vid. Even this method is frowned on by the Volvo engineers who insist nothing beats dismantling and rodding the old fashioned way.

However looking at the photos I would not have though this was scaled up enough to cause your problems.

rydlyme: https://www.ricoservices.co.uk/environmentallyfr.htm


see the bubbles in the pipe, that's the limescale fizzing off.
 
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BruceK said:
Never heard of using oxalic acid on anything other than gelcoat cleaning, the much favoured Y10 gel. Most people I have heard including myself use Rydlyme and pump it round the entire circuit for 4 hours - from the exhaust elbow inlet back through to impeller basket outlet . See vid. Even this method is frowned on by the Volvo engineers who insist nothing beats dismantling and rodding the old fashioned way.

However looking at the photos I would not have though this was scaled up enough to cause your problems.

rydlyme: https://www.ricoservices.co.uk/environmentallyfr.htm


see the bubbles in the pipe, that's the limescale fizzing off.
Click to expand...

Oxcalic won't touch it.

Hydrochloric Acid is cheap and does it rapidly . Rydlyme is the expensive version. Remove your anodes or replace post cleaning as they will be dissolved.
 
On a D12 the simplest thing to do is connect to remove the anodes and screw in barbed connectors, attached pipe and pump it round. I assume a KAD 44 exchanger will be broadly similar.

You loose a small amount of acid, but given it is E1 for 1.5 litres it does not really matter.

This then does 2 jobs. Anodes removed and a simple place to access the exchanger.

Bear in mind if it is solid the acid can't circulate and you will still have a blockage. It it more likely than not to be the ends that are worse as on mine this is the "tide mark" where it drains to.
 
Rydlyme IIRC is mixed to a 50:50 solution with water and then pumped in circulation for 4 hours. I found 10 litre enough to do both engines. Roughly £120 in cost.
 
BruceK said:
The Charge Air Cooler IIRC is aluminium. Not sure what that might do to it. Rydlyme is a safe option. But you pay your money and take your chances.
Click to expand...

Are you sure its aluminium? Mine looks like copper/brass. plus it is really heavy...

The problem is that Rydlyme is not available in Sweden. I could go to Norway to get some "Systemrens" (system cleaner) but if something that I can get hold of easier works I'd rather use that.
 
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BruceK said:
The Charge Air Cooler IIRC is aluminium. Not sure what that might do to it. Rydlyme is a safe option. But you pay your money and take your chances.
Click to expand...

I'd be surprised if it was aluminium. Plus rydlyme is just hydrochloric acid diluted to 10%.,so dilute your supermarket acid to the same level and its the same as rydlyme - surely?
 
joae said:
Then again: What concentration do you mix?
Click to expand...

The supermarket stuff is I believe 23% ish.

I dilute it 50/50 which is more than adequate. Even rinsing your bucket on the dock makes the concrete fizz.... Wear rubber gloves and eye protection - do take it seriously.

Hydrochloric Acid is also sold as brick cleaner in DIY stores.

Hydrochloric does not react with copper but it does read with zinc ( it dissolves it - hence remove or replace anodes ) and it will also destroy aluminium. I would be very surprised if the internal salt water cooled section of a marine engine ( charge cooler) were aluminium.
 
julians said:
I'd be surprised if it was aluminium. Plus rydlyme is just hydrochloric acid diluted to 10%.,so dilute your supermarket acid to the same level and its the same as rydlyme - surely?
Click to expand...


Yes but they claim a mystery additive. I looked at this a while ago and their competitors dispute this claim, as they dispute that it is safe on hands ( which I believe they claim also). Hydroloric works well.
 
julians said:
I'd be surprised if it was aluminium. Plus rydlyme is just hydrochloric acid diluted to 10%.,so dilute your supermarket acid to the same level and its the same as rydlyme - surely?
Click to expand...

I am not going to confess I know the chemical constituents of Rydlyme. I can only go by the manufacturers guarantee it is safe to use. Why would you be surprised the CAC is made of aluminium. It has very advantageous heat dissipation qualities and is definitely a non ferrous alloy whatever it is if not aluminium..
 
BruceK said:
I am not going to confess I know the chemical constituents of Rydlyme. I can only go by the manufacturers guarantee it is safe to use. Why would you be surprised the CAC is made of aluminium. It has very advantageous heat dissipation qualities and is definitely a non ferrous alloy whatever it is if not aluminium..
Click to expand...

Because it corrodes relatively easily in salt water.

Or maybe does the charge air cooler on this engine not see any raw salt water, ie it uses the engine coolant? Doesn't sound like it would cool brilliantly if the engine was circulating 90deg engine coolant through it though, so I'm guessing it does use raw sea water
 
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julians said:
Because it corrodes relatively easily in salt water.

Or maybe does the charge air cooler on this engine not see any raw salt water, ie it uses the engine coolant? Doesn't sound like it would cool brilliantly if the engine was circulating 90deg engine coolant through it though, so I'm guessing it does use raw sea water
Click to expand...

My outdrives are aluminium alloy. They are better in salt water than iron would be.
 
BruceK said:
My outdrives are aluminium alloy. They are better in salt water than iron would be.
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But they are painted/coated to prevent corrosion

Anyway regardless of the arguments I'd still be surprised if it were aluminium (unless it doesn't see any salt water, and just sees engine coolant) ,but I am just a layman expressing my opinion, I'm no expert, so if it turns out they are aluminium then colour me surprised.

I would not be surprised if they were bronze.
 
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