Cleaning saltwater heat exchange

[gertha]

Can anyone give a quick description of best way to clean a engine cooling system.
Have a lump of iron with salt water on one side and coolant on the other, the evidence last summer suggests we are a bit claged up.
Acid must be the answer, but how do I get it in and out.
Am told you can do it with unit on engine , looking for advise on best practice.

Or do I just pay Jason at French’s

 

[Concerto]

When I had my heat exchange on my engine blocked, all I did was remove it from the engine and used a small screwdriver to knock off the white deposits which were at one end only. Then washed out with fresh water from a hose. You must use new O-rings and make sure they are correctly aligned before tightening. Refill cooling system with water and antifreeze. Run engine and check water flow from exhaust and top up coolant if necessary.

 

[duncan99210]

You don't say what engine it is, which may affect the advice offered on cleaning it up.

 

[ip485]

Having very recently been there, I think a lot depends on how difficult it is to remove the heat exchanger. Possibly removing the exchanger might result in a better job, or at least clear evidence that it is rejuvenated. A set out with that intention, but with my engine it was a big job, would have taken a day, with quite a few expensive parts involved. The advantage is that if you have ever lost a piece of your impeller for example, good chance it will be sitting at the front of the exchanger.

Having removed the heat exchanger there are various commercial products for descaling including the usual acid suspects - a good soak will do the job in one of these.

In my case to avoid removing the exchanger and also to avoid using acids without being absolutely sure what they might be doing I went down the road of circulating Rydlyme through the system. It is straightforward, (instructions on their web, but essentially connect up a bucket of solution to the seawater inlet with the return back to the bucker and pump it around with a small £20 pump and wait till it stops fizzing) and in my case the results were really good, the engine now runs significantly cooler and clearly there was a reasonable amount of clag.

Well worth the job and very pleased with the results without too much fuss as well.

 

[gertha]

Engine is a Perkins 4.154
I think the heat exchange says Bowman, but that may be my memory wrong, will confirm tomorrow .

simon

 

[Yngmar]

I've taken the end caps off the tube stack, cleaned the calcium deposits off with a putty knife and then poked each tube through with a thick piece of wire until I could look through all of them again. O-Rings were still good and went back in with some fresh grease on them.

There wasn't enough calcium left to bother with chemicals and it wouldn't have worked without clearing the tubes first as the liquid wouldn't get far enough into a blocked tube.

 

[oldmanofthehills]

In my case to avoid removing the exchanger and also to avoid using acids without being absolutely sure what they might be doing I went down the road of circulating Rydlyme through the system..

Rydlyme is a mild acid, as nothing else will shift lime scale. But easier to pump it through than remove heat exchanger and drop it in an acid bath, even on accessible engines.

 

[findus]

I had the same problem, engine overheating and taking the end caps off it looked pretty much like in the picture. What I did find after taking the stack out was, that the lime scale was not on the salt water side (that looked as clean as in the picture) but it was on the engine circuit, the fresh water side. It took weeks of using a lime scale remover in a bucket to get the lime scale cover off even though the man from Beta was talking about 20 mins...
I bought a new heat exchanger stack and after cleaning used the old one as a spare.
I would definitely take the stack out and check the other side.

 

[Yngmar]

I had the same problem, engine overheating and taking the end caps off it looked pretty much like in the picture. What I did find after taking the stack out was, that the lime scale was not on the salt water side (that looked as clean as in the picture) but it was on the engine circuit, the fresh water side. It took weeks of using a lime scale remover in a bucket to get the lime scale cover off even though the man from Beta was talking about 20 mins...
I bought a new heat exchanger stack and after cleaning used the old one as a spare.
I would definitely take the stack out and check the other side.

I don't understand why there would be any limescale buildup on the coolant side of the tube stack, unless perhaps hard tapwater was used to mix with coolant concentrate instead of demineralized water or ready-mix coolant.

 

[findus]

I don't understand why there would be any limescale buildup on the coolant side of the tube stack, unless perhaps hard tapwater was used to mix with coolant concentrate instead of demineralized water or ready-mix coolant.

Believe me, that was exactly my thought at the time. I did rod the tube stack first but it seemed to be almost clean and the engine still started overheating above 60% load. That was the point where I thought I have to pull the stack out.
I assume, that the coolant has been refilled several times with tap water. It's what you get, when you buy a used boat, lots of little surprises...

 

[emandvee44]

I am planning to clean the seawater side of my D2-55 cooling system, using Rydlyme. I note that there are two ways to do this; the circulating method recommended by Rydlyme, or the fill and stand method used by several on here. As I do not have a pump, I will use the latter method.
Can anyone advise how much Rydlyme I will need?
Cheers,

Michael.

 

[garvellachs]

Believe me, that was exactly my thought at the time. I did rod the tube stack first but it seemed to be almost clean and the engine still started overheating above 60% load. That was the point where I thought I have to pull the stack out.
I assume, that the coolant has been refilled several times with tap water. It's what you get, when you buy a used boat, lots of little surprises...

A quick Google of hard water suggests it can contain up to 375 mg per litre of minerals in the extreme. So an engine filled with tap water might have say 1g or 2g of minerals in its coolant. That's not much - it will take several re-fills to block a heat exchanger on the coolant side?

Seawater is a different story and a much more likely source, esp if the exchanger is leaking from one side to the other?

 

[ip485]

Michael - my guess is that it will depend on how much contamination you have. You will have a good idea how contaminated the Rydlyme is if you take a sample of the expelled solution. Either it will still react or not, in which case it is spent and another fill will be required. The "muck" in it will be an indication. If there is a lot of scale I suspect it will take quite a few fills.

 

[peteK]

This building up of limescale in heat exchanger seems to be associated with where you keep the boat .I have never had to clean scale off the matrix tubes so perhaps the south coast is prone to it.