Engine descaling

[PaulRainbow]

Engines due for a service, which will include flushing the raw water circuit. I normally use Rydlyme, but these engines are big and Rydlyme isn't cheap.

Considering Bostik brick acid, which is apparently 16% HCL. What would be a sensible mixing ratio ?

Any other alternatives ?

 

[Roberto]

Any other alternatives ?

Have a look at sulphamic acid, 50-100 g/l is a good practical concentration for heat exchangers descaling. Final neutralization with a sodium bicarbonate rince.

 

[AntarcticPilot]

Engines due for a service, which will include flushing the raw water circuit. I normally use Rydlyme, but these engines are big and Rydlyme isn't cheap.

Considering Bostik brick acid, which is apparently 16% HCL. What would be a sensible mixing ratio ?

Any other alternatives ?

is that 16% of concentrated Hydrochloric acid, or 16% of HCl? The former would be fine; the latter would need diluting about 3 to 1. It isn't an exact thing, thoug.

 

[PaulRainbow]

is that 16% of concentrated Hydrochloric acid, or 16% of HCl? The former would be fine; the latter would need diluting about 3 to 1. It isn't an exact thing, thoug.

The data sheet says "Solution of 16% hydrochloric acid"

 

[AntarcticPilot]

The data sheet says "Solution of 16% hydrochloric acid

That's not terribly specific, but I guess it means 16% concentrated hydrochloric acid, which should be fine as is, or maybe diluted with an equal volume of water. Concentrated hydrochloric acid actually contains about 35% HCl, so 16% of that is about 6% HCl.

 

[Moonbeam]

I seem to recall Volvopaul posting that care should be taken using brick cleaners etc for this application. If I remember correctly, he said there is something in them that is not kind to the soldering on the copper tubes in the heat exchangers etc.

In fact, had a quick search, here is the thread... Cleaning Volvo Penta D4 heat exchanger

If this is for you Princess with older Volvos, it might not be relevant.

 

[vyv_cox]

Rydlyme is hydrochloric acid, according to the data sheet, less than 10% concentration. Adobe Acrobat

 

[Refueler]

I seem to recall Volvopaul posting that care should be taken using brick cleaners etc for this application. If I remember correctly, he said there is something in them that is not kind to the soldering on the copper tubes in the heat exchangers etc.

In fact, had a quick search, here is the thread... Cleaning Volvo Penta D4 heat exchanger

If this is for you Princess with older Volvos, it might not be relevant.

Comments also come out when its suggested to use Central Heating Cleaner for the job - outboards etc.

 

[AntarcticPilot]

I seem to recall Volvopaul posting that care should be taken using brick cleaners etc for this application. If I remember correctly, he said there is something in them that is not kind to the soldering on the copper tubes in the heat exchangers etc.

In fact, had a quick search, here is the thread... Cleaning Volvo Penta D4 heat exchanger

If this is for you Princess with older Volvos, it might not be relevant.

I've only used it on a raw water cooled engine, so no heat exchanger. However, the older types of solder likely to have been used in a marine engine are lead/tin mixtures, and neither is particularly affected by hydrochloric acid. I'd certainly not leave the acid in the system for too long, but a short - hours rather than days - exposure should be ok. Of course, zinc anodes should be removed!

 

[vyv_cox]

That's not terribly specific, but I guess it means 16% concentrated hydrochloric acid, which should be fine as is, or maybe diluted with an equal volume of water. Concentrated hydrochloric acid actually contains about 35% HCl, so 16% of that is about 6% HCl.

The HCl we buy in Greece used to be labelled 20% but more recently is 6%, sometimes w/w. As you say, pretty much the same concentration. In Spain Aqua Fuerte from ferreterias is 6%.

 

[PaulRainbow]

I seem to recall Volvopaul posting that care should be taken using brick cleaners etc for this application. If I remember correctly, he said there is something in them that is not kind to the soldering on the copper tubes in the heat exchangers etc.

In fact, had a quick search, here is the thread... Cleaning Volvo Penta D4 heat exchanger

If this is for you Princess with older Volvos, it might not be relevant.

Yes, it's for my Princess, 1988 TAMD71a's

 

[neil_s]

I use Fernox DS3 in my Bukh.

 

[wingcommander]

Spirit of salts ( its usually around 20% hydrochloric acid ) also works wonders.

 

[Refueler]

I use Fernox DS3 in my Bukh.

Fernox ... that's the name I was trying to remember ...

Fernox is in various formats to suit different boiler constructions ... the old days of just the one for cast iron are long gone ... now they cover Alloys of many types etc.

 

[wingcommander]

The main concerns with Fernox DS3 is that it practically 90 % Sulphamic acid . Which is extremely harmful to aquatic life. Also more expensive than good old spirit of salts (hydrochloric acid ,which is much better at dissolving limescale).. proven by myself when cleaning plate to plate heat exchangers on modern combination boilers. Just gotta be more careful with it.

 

[PaulRainbow]

That's not terribly specific, but I guess it means 16% concentrated hydrochloric acid, which should be fine as is, or maybe diluted with an equal volume of water. Concentrated hydrochloric acid actually contains about 35% HCl, so 16% of that is about 6% HCl.

Hmm, Rydlyme say mix at 4:1 so 5l diluted will give me 25l for about £70

Cheapest brick acid looks to be about £12. Used neat would cost £60 for 25l, so not much saving. Mixed 50:50 would save a bit, but is that strong enough ?

 

[PaulRainbow]

The main concerns with Fernox DS3 is that it practically 90 % Sulphamic acid . Which is extremely harmful to aquatic life. Also more expensive than good old spirit of salts (hydrochloric acid ,which is much better at dissolving limescale).. proven by myself when cleaning plate to plate heat exchangers on modern combination boilers. Just gotta be more careful with it.

What strength of hydrochloric acid do you suggest ?

 

[Poignard]

My raw-water cooled BUKH DV10 is 42 years old and I have owned it for 27 years.

I have never flushed it out, when laying up, with anything except fresh water.

Here is an extract from the Owner's Manual, and it makes no mention of any need to flush with any kind of acid. Nether does the Workshop Manual.

So I don't.

Can anyone explain to me why I should?

 

[Refueler]

Why >

Perkins say clearly in their older 4 series manuals about deposits of salts etc if raw cooled engine runs at same temp as heat exchanger version ... Basically raw cooled engines should be run cooler to avoid salts deposits.

That in itself gets me thinking that flushing out an engine is not a bad idea - whether raw or heat exchanger.

 

[oldgit]

Have used this in the past.
Marine Dynamic Descaler 5L Ridlime Rydlime Ridlyme Rydlyme | eBay

Do know that a fellow boat owner with a Princess 360 had some remarkable results descaling a pair of 380HP engines.
This involved circulating the descaler for total of 6 hours in each engine
Three hours in one direction and then reversed the flow for another three hours.
Patience was a virtue.
From memory the water pump on one engine was an absolute PIA to get at to remove impeller.