Coolant flush - Any good howtos? What about this?

[gregcope]

Hi,

I changed the coolant on our Volvo 2030B this weekend and was surprised at its state. Looked dirty, had small bits in it. This should have been around two years old and volvo green colour...

I replaced it with Blue Comma diluted coolant. Due to time constraints of other getting on water stuff I moved on.

So, I want to clean and flush. Any good howtos?

I was thinking of;

1. Draining
2. Refilling with RYDLYME MARINE DESCALER, running the engine for a minute to circulate and leaving it in for a few hours, drain and then run this out through the raw water to clean those pathways
3. Flush by filling with fresh tap water and running engine for a minute to circulate and drain
4. Maybe repeat 3.
5. Refill with diluted Comma coolant

Thoughts?

 

[TernVI]

You should not need to 'descale' the closed coolant circuit.
If your coolant is getting dirty very quickly, I suspect something is wrong, and adding acid descaler won't help, execept it might make the problem obvious?
I've recently flushed out a bike's cooling system, I just ran a hose through every bit until it ran clean. That's not going to be easy in a boat afloat.
You may need to remove the thermostat to get everything to drain.
A wet vac is very useful, for cleaning spillages and sucking coolant out of the block etc.

I think I would run the engine for a bit, drain it as best I could, then refill with plenty of the right antifreeze and monitor it.

 

[gregcope]

Hi @TernVI thanks. So your suggested just flush it. Lots. With generic water.

i cannot really run a hose as the drain is tiny and flow is pretty weak, which as you point out might be thermostat related, which on a 2030 is not easy to remove.

i can drain, fill with water, repeat and miss the descale step.

 

[Kinsale373]

I've used descaler on the Raw Water side of a 2040 with good results. I'd check with someone who works on Volvo Pentas about using it on the Coolant side.
Can you identify what type of " bits" you have in the coolant. Are they rubber, metalic , Scale or Gel like.
I've heard of issues with some coolants turning to globs or gel.
You seem unsure of when the coolant was last changed. Maybe its worth just draining and replacing and monitoring. Especially if this is all preventative work and you don't have any cooling issues.
Kinsale 373

 

[gregcope]

I would say it was general gunk/slime. Nothing really identifiable.

Without checking invoices i think the coolant was last changed in late 2018. The boat has had very little use since then.

I do not have an obvious coolant problem. Without a temp guage i would guess the engjne is around 60-70c when warm is hot to touch. The heat exchanger is working well as the housing is hot to the touch but not vhot. I would assume 50c.

Having recently blasted, faired and copper coated the boat easily achieves 7kts under full power (3200rpm). The y elbow is clear although this is hard to tell with a high rise elbow.

 

[thinwater]

(I served many years on the joint US/UK ASTM committee for engine coolants and flushing chemicals.)

Unless you have a cooling system performance problem, just change the coolant every two years. Alternativly, you can flush with distilled or DI water (not tap water--you will have to flush that !) if you feel a strong need. But the chemicals can do harm and you have to get ALL of it out, so better not to unless you have a significant problem. and THAT is the behind-the-doors advice of the people who make the chemicals.

 

[gregcope]

thanks @thinwater Good point.

 

[PaulR]

Hi Greg,

on my 2030 I have flushed the fresh water coolant with hose only but have also removed the heat exchanger and cleaned it thoroughly with a descaler (I used dynamic descaler) and also had to use kebab sticks to gently unblock some of the heat exchanger tubes - made a positive difference to running temperature especially when working engine hard (we have fitted temp gauge)

 

[PaulR]

appreciate you are asking about fresh water side but just in case you wanted to clean the seawater part of the heat exchanger I found this quite useful - mind you my heat exchanger looks slightly diferent (the tubes are enclosed in a larger bore cylinder )

MD2030 Heat Exchanger Clean and Coolant Drain Tap

 

[jwfrary]

There are automotive coolant flush products out there

liquid moly make a good one.

I have been told in the past by a main engine dealer that shall remain nameless he used dishwasher tablets....I have no idea how effective they would be I’m not suggesting it’s a good idea!

the real deal available from your local motor factor is likely the best thing

 

[gregcope]

appreciate you are asking about fresh water side but just in case you wanted to clean the seawater part of the heat exchanger I found this quite useful - mind you my heat exchanger looks slightly diferent (the tubes are enclosed in a larger bore cylinder )

MD2030 Heat Exchanger Clean and Coolant Drain Tap

Yes read that!

I have cleaned the heat exchanger. It was quite clogged (30%). I have a pic of before/after that i need to downscale for the forum software.