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Pladdatoo

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Got round to replacing the internal anodes on my 3GM30 raw water cooled Yanmar today and couldn't help but notice that the waterways within the engine appeared like an old furred up kettle!

I would love to give them a clean out, but how?
It definitely appeared to be lime scale-type buildup.

Anybody done some similar and if so and with what.
I was thinking about oxalic acid, but would that do any hard else where? And how. Might you get in in and keep it in long enough to do any good?

Cheers

pladda
 
Pladdatoo said:
Got round to replacing the internal anodes on my 3GM30 raw water cooled Yanmar today and couldn't help but notice that the waterways within the engine appeared like an old furred up kettle!

I would love to give them a clean out, but how?
It definitely appeared to be lime scale-type buildup.

Anybody done some similar and if so and with what.
I was thinking about oxalic acid, but would that do any hard else where? And how. Might you get in in and keep it in long enough to do any good?

Cheers

pladda
Click to expand...

When we sold our liveaboard mobo here in Florida, the buyer's survey seatrial found some slight overheating on both engines when at full throttle and we had to engage an engineer at the buyer's insistence who did a descale which he did by recirculating some stuff (not sure what) from a big bucket for an hour or two. Another seatrial proved all was then ok and the sale went ahead. He told me the job was commonly needed and he had the pump and bucket setup all ready to go.
 
Last edited:
Pladdatoo said:
I would love to give them a clean out, but how?
It definitely appeared to be lime scale-type buildup.

Anybody done some similar and if so and with what.
I was thinking about oxalic acid, but would that do any hard else where? And how. Might you get in in and keep it in long enough to do any good?

Cheers

pladda
Click to expand...

Rydlyme as suggested alternatively a sulphamic acid based central heating boiler and general de-scaler such as Fernox DS-3 http://www.fernox.com/files/Fernox/Content/PDF/English/DS3 2kg new.pdf

Sulphamic scid is stronger than the weak organic acids such as citric, oxalic etc but not as strong as, for example, hydrochloric acid.

The organic acids will do the job but will take a lot longer than sulphamic acid.

The exact nature of Rydlyme remains a mystery to me. I think it is hydrochloric acid based but buffered in some way to reduce its effectrive strength.

Do not fit the new anode until you have done the acid clean.
 
Pladdatoo said:
Good thinking, thanks (and to all).

I assume remove pipe from sea cock and get engine to pump the stuff around for a while ?
Click to expand...

as long as the engine pumps it back to the source container AND it doesn't get too hot doing so on a continuous basis . I think the guy that did our mobo rigged a circular circuit and used a separate pump own rather than running the @250hp engines to do so
 
Robin said:
I have no idea, maybe he was just running it through the heat exchangers and not the whole water jacket? I know he also took the end caps of the heat exchangers and found broken bits of zinc anodes blocking some of the heat exchanger tubes.
Click to expand...

I've spent quite some time clearing the crumbled remnants of anodes from my heat exchangers. When ordering new pencil anodes I was surprised to hear that they should be changed every 3 months! I'll probably aim for twice yearly, but more likely once a year.
 
VicS said:
Rydlyme as suggested alternatively a sulphamic acid based central heating boiler and general de-scaler such as Fernox DS-3 http://www.fernox.com/files/Fernox/Content/PDF/English/DS3 2kg new.pdf

Sulphamic scid is stronger than the weak organic acids such as citric, oxalic etc but not as strong as, for example, hydrochloric acid.

The organic acids will do the job but will take a lot longer than sulphamic acid.

Is all

The exact nature of Rydlyme remains a mystery to me. I think it is hydrochloric acid based but buffered in some way to reduce its effectrive strength.

Do not fit the new anode until you have done the acid clean.
Click to expand...

Is this stuff safe to use with aluminium engines, or parts of them like alloy cylinder heads?
 
Robin said:
I have no idea, maybe he was just running it through the heat exchangers and not the whole water jacket? I know he also took the end caps of the heat exchangers and found broken bits of zinc anodes blocking some of the heat exchanger tubes.
Click to expand...

If you have a heat exchangers its fresh water cooled not raw water cooled. A whole different kettle of fish to the OP's raw cooled engine. You not normally expect the fresh water circuit to need cleaning. The raw water side of the heat exchanger could be acid cleaned by circulating the cleaning solution though it. The sea water pump need not be part of the circuit (or its impeller could be removed) and the thermostat is not part of the raw water circuit anyway.
 
Robin said:
Is this stuff safe to use with aluminium engines, or parts of them like alloy cylinder heads?
Click to expand...

They say Rydlyme is and Fernox simply say DS3 should not be used on badly corroded or thin gauge aluminium.
 
longjohnsilver said:
I've spent quite some time clearing the crumbled remnants of anodes from my heat exchangers. When ordering new pencil anodes I was surprised to hear that they should be changed every 3 months! I'll probably aim for twice yearly, but more likely once a year.
Click to expand...

Dont forget once the anode has gone the heat exchanger is the next thing to corrode.
 
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