White goop in my heat exchanger?

[O C Diver]

So I'm doing the 5,000 hour service which includes the cooling system. There is a tube bundle core that is held in place with 2 end caps. The first end cap has this white goop in it. It's about the consistency of pudding or yogurt. Basically it blocked about half of the tubes plus the raw water feed to the stuffing box.

I'm trying to figure out what it is. The only things that come to mind are something produced by the aluminum anode in the center or pureed jelly fish. Doubt the jelly fish would have gotten through the sea strainer.

Anyone know what it is?



Ted

 

[RT Firefly]

Greetings,
Mr. OC. Just a WAG but...



"Aluminium hydroxide also forms a gelatinous precipitate in water." From this Wiki entry: https://en.wikipedia.org/wiki/Aluminium_hydroxide

 

[kchace]

Yes, I also think it’s from the anode.

Ken

 

[Choices]

I get it also from my cooler. Happens to be near anode.

I switched to aluminum anodes, think that is it?

 

[O C Diver]

Sounds like we have a winner. The other end didn't have the goop, but then there was nothing keeping it from going into the exhaust elbow and out.

Thanks!

Ted

 

[Each finger a marlinspike]

Yes, aluminum hydroxide, often called "Poultice Corrosion" and most often found whenever wood comes in contact with aluminum. The cause is because aluminum is not exposed to air and can't maintain its protective layer.

 

[HeadedToTexas]

It if foams when you add drops of acid (like Barnacle Buster or even vinegar) to it, it's calcium carbonate. If not, aluminum hydroxide is a great bet. Is the aluminum anode right there too?

 

[North Baltic sea]

Hi

very interesting topic.

It must have been quite a surprise to open the lid and find the mysterious "amoeba".

At first I thought it looked like silicone grease, which is used to lubricate a new raw water pump ruber, but there is too much slime. Interesting if it is oxidation.

NBs

 

[Greg QS]

This is a perfect example of why cooling services are so important. It is a time thing, not an hour thing. How long has it been in time since your last cooling system cleaning?

 

[twistedtree]

What are the implications? Is it a problem, and if so, what’s happening?

 

[Greg QS]

The implication are a 50% reduction cooling capacity in this case. Also the loss of cooling to the stuffing box. Its only a problem if left un checked and allowed to build up. I would recommend inspecting this area yearly and cleaning out . Then determine how often it needs to be done and proceed accordinglly.

I am in a salt environment so we use zinc. The trouble with zinc is as it dissolves it re deposits down stream in the system. Not in the form a goop, but as a white scale. This reduces cooling capacity. Again another reason the systems need to be cleaned. You will get the same amount of deposits in the system over a period of time regardless of engine hours. This is why the system cleanings should be based on time not engine hours.

 

[twistedtree]

The implication are a 50% reduction cooling capacity in this case. Also the loss of cooling to the stuffing box. Its only a problem if left un checked and allowed to build up. I would recommend inspecting this area yearly and cleaning out . Then determine how often it needs to be done and proceed accordinglly.

I am in a salt environment so we use zinc. The trouble with zinc is as it dissolves it re deposits down stream in the system. Not in the form a goop, but as a white scale. This reduces cooling capacity. Again another reason the systems need to be cleaned. You will get the same amount of deposits in the system over a period of time regardless of engine hours. This is why the system cleanings should be based on time not engine hours.

So it's from aluminum anodes vs zinc anodes? It's not some sort of wasting of the cooler components themselves?


Sounds like it's all normal, and just needs to be cleaned more frequently?

 

[Greg QS]

With aluminum anodes in fresh water correct on both

 

[Cleanslate]

Wondering if you kept some around long enough to dry out and spoil?
Then get a sniff of it? Did it smell like spoiled fish ? Then it could be jelly fish , or whatever that got thru the strainer etc. Our motors create on hell of a suction .

But what ever it is , it’s a very interesting topic thanks for posting.
I subscribe with the total time , instead of running hours on the cooling side of the engine. Water is just sitting in there all of the time whether running
Or not , causing normal corrosion and wear.

 

[Choices]

In the cooling bundle water comes in one half then turns and exits on the other half. The anode is in that 180 degree turn, with the gel.

I think it can easily get blow out with rpms. But my next in line tranny cooler tubing is much smaller.

 

[O C Diver]

It if foams when you add drops of acid (like Barnacle Buster or even vinegar) to it, it's calcium carbonate. If not, aluminum hydroxide is a great bet. Is the aluminum anode right there too?

Yes, what's left of the anode is in the center.

Ted

 

[O C Diver]

This is a perfect example of why cooling services are so important. It is a time thing, not an hour thing. How long has it been in time since your last cooling system cleaning?

It's been 3 years and almost 2,500 hours. Anodes are changed annually. Boat spends about 75% of its engine hours in fresh water, 20% in Brackish, and 5% in saltwater. It sits 4 months a year in Brackish.

Ted

 

[O C Diver]

What are the implications? Is it a problem, and if so, what’s happening?

I noticed on the trip to Fort Pierce that the engine was running about 10 degrees warmer (190 degrees). So a change but not anywhere near warm. The stuffing box feed isn't necessary, but I liked the concept. Shaft is only turning 480 RPM. It was time to do my 5,000 hour service and was expecting to see some accumulation in the tube bundle.

Ted

 

[O C Diver]

In the cooling bundle water comes in one half then turns and exits on the other half. The anode is in that 180 degree turn, with the gel.

I think it can easily get blow out with rpms. But my next in line tranny cooler tubing is much smaller.

Not on this engine. The 4045 tube bundle is a single pass heat exchanger. I would guess about a third of the tubes had limited to no flow. My normal cruise RPM is 1,200 to 1,500. So there's only about 20 GPM going through the heat exchanger.

Ted

 

[Choices]

I remembered you had a Deere. Mine is a 135 Lehman. I also go back and forth in water types.

My anodes last about 4-6 months. I change them with the oil, around 100-125 hrs.