MD2030B Freshwater Cooling Circuit Flush

[SimonP85]

While out this weekend I noticed a small amount of water weeping from the hose on the water pump on our 2030B (at 17/16 in the diagram here so the pressure side of the pump).

The engine is also connected to the calorifier circuit and feeling/squeezing the hoses to/from this there is a noticeable crunch which I assume is a build up of limescale in the hoses. The setup is identical to this picture here.

I'm concerned that this may not be limited only to the hoses and that there is a build up of scale etc in the engine which is causing the system/pump to be over pressurised and causing the above weeping and potentially overheat in the future.

I've read about people people flushing the raw water circuit with solutions such as Rydlyme but can this also be done on the closed fresh water circuit? If so how would anyone suggest doing this? I assume I could connect a drill piston pump or similar either side of the engine water pump to circuit the solution, but would this achieve much with the engine cold and thermostat closed? I intend to replace the calofier hoses and also the (extortionate) Volvo hoses for the water pump (14 & 16 in the above Penta Shop link).

Any guidance much as appreciated.

 

[pvb]

I'm surprised that there'd be much build-up of limescale in a sealed freshwater circuit containing appropriate inhibiting antifreeze.

 

[PaulRainbow]

I agree with post #2. Make sure when you're done the system has a 50/50 mix of coolant and water.

Never tried Rydlyme in the raw water circuit, but can't see how it would hurt. You will need to take the thermostat out. A drill pump is not really suitable as you need to pump it round for an hour or two. Disconnect a hose, extend it and connect it to a bilge pump in a bucket of Rydlyme. Connect another hose to the fitting where the pipe was connected and drop this in the bucket. Turn the pump on and leave it running.

As for Volvo hoses, check with a motor factors to see if they keep anything suitable.

 

[VicS]

I'm surprised that there'd be much build-up of limescale in a sealed freshwater circuit containing appropriate inhibiting antifreeze.

+1, at least if the recommendation to use distilled water for dilution, or ready dilted antifreeze , has been followed.

 

[PaulR]

good timing as thinking of doing same on our 2030 - to circulate product in freshwater system my plan is to drain the existing antifreeze - flush through with fresh tap water and then refill with appropriate mixture (I am planning to use dynamic descaler) and then to run the engine upto temperature so the descaler gets warmed up and through the entire freshwater circuit - leave it for a period of time (not sure how long currently) then redrain - flush again with tap water and refill with fresh antifreeze mixture ,

am also intending to do similar for seawater circuit but was hoping I could flush that system with fresh water by putting inlet hose in bucket rather than seawater strainer and once engine warm- suck a mix of the descaler into the raw water circuit and then leave it to do its stuff before reconnecting sea water inlet again and running it through to flush system


one question though - dynamic descaler is not suitable if cooling circuits contain any aluminium elements - anyone know if 2030 b has any aliminium bits in the cooling circuits????

 

[pvb]

good timing as thinking of doing same on our 2030 - to circulate product in freshwater system my plan is to drain the existing antifreeze - flush through with fresh tap water and then refill with appropriate mixture (I am planning to use dynamic descaler) and then to run the engine upto temperature so the descaler gets warmed up and through the entire freshwater circuit - leave it for a period of time (not sure how long currently) then redrain - flush again with tap water and refill with fresh antifreeze mixture ,

am also intending to do similar for seawater circuit but was hoping I could flush that system with fresh water by putting inlet hose in bucket rather than seawater strainer and once engine warm- suck a mix of the descaler into the raw water circuit and then leave it to do its stuff before reconnecting sea water inlet again and running it through to flush system


one question though - dynamic descaler is not suitable if cooling circuits contain any aluminium elements - anyone know if 2030 b has any aliminium bits in the cooling circuits????

Why on earth would you think it's necessary to descale a freshwater system??

 

[VicS]

While out this weekend I noticed a small amount of water weeping from the hose on the water pump on our 2030B (at 17/16 in the diagram here so the pressure side of the pump).

The engine is also connected to the calorifier circuit and feeling/squeezing the hoses to/from this there is a noticeable crunch which I assume is a build up of limescale in the hoses. The setup is identical to this picture here.

I'm concerned that this may not be limited only to the hoses and that there is a build up of scale etc in the engine which is causing the system/pump to be over pressurised and causing the above weeping and potentially overheat in the future.

I've read about people people flushing the raw water circuit with solutions such as Rydlyme but can this also be done on the closed fresh water circuit? If so how would anyone suggest doing this? I assume I could connect a drill piston pump or similar either side of the engine water pump to circuit the solution, but would this achieve much with the engine cold and thermostat closed? I intend to replace the calofier hoses and also the (extortionate) Volvo hoses for the water pump (14 & 16 in the above Penta Shop link).

Any guidance much as appreciated.

good timing as thinking of doing same on our 2030 - to circulate product in freshwater system my plan is to drain the existing antifreeze - flush through with fresh tap water and then refill with appropriate mixture (I am planning to use dynamic descaler) and then to run the engine upto temperature so the descaler gets warmed up and through the entire freshwater circuit - leave it for a period of time (not sure how long currently) then redrain - flush again with tap water and refill with fresh antifreeze mixture ,

am also intending to do similar for seawater circuit but was hoping I could flush that system with fresh water by putting inlet hose in bucket rather than seawater strainer and once engine warm- suck a mix of the descaler into the raw water circuit and then leave it to do its stuff before reconnecting sea water inlet again and running it through to flush system


one question though - dynamic descaler is not suitable if cooling circuits contain any aluminium elements - anyone know if 2030 b has any aliminium bits in the cooling circuits????

Rydlyme and Dynamic Descaler are both hydrochloric acid based. The fresh water circuit really should not need anything as aggressive. Take care if you do use them. Personally I would be looking for something less aggressive and not based on a strong mineral acid. I'd be looking towards a sulfamic acid based descaler or even one based on a much weaker organic acid.

 

[SimonP85]

Many thanks for the rapid replies.

The mix has been 50/50 or thereabouts since we've had the boat but I can't commend before that.

For anyone familiar with this engine and just to confirm my own understanding, from the water pump there are two routes: one into the engine block and another the short length of rubber hose in the base of the heat exchanger:

View attachment 65442

The circulation pumps draws water from the bottom of the header tank (behind the alternator).

When the engine is cold, according to the workshop manual the thermostat keeps the channel to the heat exchanger closed. If I understand correctly this means the water flows directly into the engine block. Is there another route then back into the pump that entirely bypasses the heat exchanger? I can't see anything obvious on the diagrams etc... My understanding here may be totally flawed so if anyone can confirm or correct it would be great.

Thanks!

 

[pvb]

Rydlyme and Dynamic Descaler are both hydrochloric acid based. The fresh water circuit really should not need anything as aggressive. Take care if you do use them. Personally I would be looking for something less aggressive and not based on a strong mineral acid. I'd be looking towards a sulfamic acid based descaler or even one based on a much weaker organic acid.

At the risk of repeating myself, why on earth would you think it's necessary to descale a freshwater system?? How often do you descale the cooling system in your car engine?

 

[PaulR]

interesting question - but kettles are freshwater only and build up scale - presumably antifreeze if maintained over the near 20 years before we bought this boat prevents scale build up but any way we can tell ?

 

[SimonP85]

Hi pvb

I appreciate this would not normally be required, but as mentioned in my first post I'm concerned that the system may not have been treated as it should have been in the past (50/50 mix and distilled water) and so scale has been able to form as potentially evidenced from the "crunch" when squeezing the hoses to the calorifier.

It may be that on removing the hoses there is nothing and it's just perished rubber but if not I'd rather be prepared with a suitable solution.

Cheers

 

[PaulR]

Rydlyme and Dynamic Descaler are both hydrochloric acid based. The fresh water circuit really should not need anything as aggressive. Take care if you do use them. Personally I would be looking for something less aggressive and not based on a strong mineral acid. I'd be looking towards a sulfamic acid based descaler or even one based on a much weaker organic acid.

Vic- thanks for your guidance - can you guide me on a brand name for a sulfamic or organic descaler that might be less aggressive and ok for the fresh water circuit please?

 

[pvb]

Hi pvb

I appreciate this would not normally be required, but as mentioned in my first post I'm concerned that the system may not have been treated as it should have been in the past (50/50 mix and distilled water) and so scale has been able to form as potentially evidenced from the "crunch" when squeezing the hoses to the calorifier.

It may be that on removing the hoses there is nothing and it's just perished rubber but if not I'd rather be prepared with a suitable solution.

Cheers

You have to ask yourself where the scale could have come from. Unless the cooling system has been emptied and refilled on a weekly basis, it simply isn't possible for enough scale to have been deposited from a sealed system.

 

[pvb]

interesting question - but kettles are freshwater only and build up scale - presumably antifreeze if maintained over the near 20 years before we bought this boat prevents scale build up but any way we can tell ?

Lousy analogy - kettles are constantly being refilled with fresh water; the boat's cooling system isn't. Indeed, the usual problem is that boat engines are rarely drained and refilled with coolant.

 

[SimonP85]

You have to ask yourself where the scale could have come from. Unless the cooling system has been emptied and refilled on a weekly basis, it simply isn't possible for enough scale to have been deposited from a sealed system.

As mentioned the only evidence I have so far is the weeping hose join and crunchy hose. It won' be until later this week that I can investigate further. Perhaps in this case just a flush and refill with ready diluted coolant will be sufficient.

 

[duncan99210]

The 'crunchy' hose could well be down to something other than limescale, such as the hose components breaking down and loosing elasticity, hence feeling crunchy not rubbery. AA to the leak where you describe it, probably nothing more than a loosened hose clip perhaps?

 

[VicS]

interesting question - but kettles are freshwater only and build up scale - presumably antifreeze if maintained over the near 20 years before we bought this boat prevents scale build up but any way we can tell ?

AFAIK antifreeze does not prevent scaling.

Vic- thanks for your guidance - can you guide me on a brand name for a sulfamic or organic descaler that might be less aggressive and ok for the fresh water circuit please?

For a sulfamic acid based descaler I would probably choose Fernox DS3 ( available from most plumbers merchants) although a 2 kg tub will be rather more than needed but always handy for kettles etc.

For an organic acid based descaler id probably try Holts 2 part Radfush, which is citric acid based, and could be used in exactly the same way as for a car engine descale.

 

[PaulR]

thanks all for your guidance

 

[johnphilip]

You have to ask yourself where the scale could have come from. Unless the cooling system has been emptied and refilled on a weekly basis, it simply isn't possible for enough scale to have been deposited from a sealed system.

Only too aware of the issue of scale in the fresh water side. Whether it was not changing the coolant regularly or (as the engineer I have had to resort to believes) at some time salt was entering through a fault in the heat exchanger connections. I had overheating, replaced the fresh water pump, found the spigot on the bottom of the heat exchanger almost blocked solid with crud and this year replacing the head and having the injectors checked . Oh and a push rod snapped. most of this on earlier threads.

 

[SimonP85]

Thanks all for the replies, very useful as always.

Can anyone explain this last bit below?

When the engine is cold, according to the workshop manual the thermostat keeps the channel to the heat exchanger closed. If I understand correctly this means the water flows directly into the engine block. Is there another route then back into the pump that entirely bypasses the heat exchanger? I can't see anything obvious on the diagrams etc... My understanding here may be totally flawed so if anyone can confirm or correct it would be great.

Thanks!