Brown Coolant Sludge / Flush Cleaner Fluids

[goldenstate]

I'm seeking experience/opinions on the use of radiator flush products in a marine diesel coolant loop.

After being out of the water for four months, a great amount of sediment/sludge has settled out of the coolant in my engine.

My internet research suggests that some possible explanations for the sludge include:

1. Unspecified corrosion in the coolant loop.
2. Mistaken mixing of different coolant types (causing additives to 'drop out')
3. A leaking head gasket allowing oil to pass into the coolant.

#3 is potentially a death knell for the motor.

The sludge I have found has no oily quality, the engine oil itself is not milky, and the sludge I have found settled to the bottom of various parts of the system (recovery tank, heat exchanger) rather than floating on top, as one might expect lighter-than-water oil to do. So I'm going with explanation 1 or 2 and seeing what happens.

To date, my coolant strategy has been, "Motor seems to be working, let's go sailing." As in, I have not replaced it since I bought the boat in late 2019 and put about 45 hours on the engine.



So, my plan at this point is to try to clean/flush the coolant entirely, and re-fill with manufacturer-specified coolant etc.

Has anyone ever used a radiator flush fluid product on his/her marine diesel? Like:

Amazon.com: Prestone AS105 Radiator Flush and Cleaner - 22 oz.: Automotive

Buy Prestone AS105 Radiator Flush and Cleaner - 22 oz.: Radiator - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

As to the usefulness of the flushing liquid, the internet predictably offers a range of opinion, from, "That won't work fer nuthin'" to "My good man you will irretrievably damage your combustion engine."

If I do not use the flush liquid, my plan will be to jerry-rig a garden hose flush of the heat exchanger, (I have already pulled the central element and cleaned the tubes.) This is the part (and all of the loop around the engine block) that is difficult to clean without flushing:



Tap water is "ionized" so after garden hosing, a subsequent draining and flush with distilled water would follow, then properly-mixed coolant replacement.

 

[Christian Williams]

There's a coolant drain on my engine block, but I just disconnected the heat exchanger and water heater hoses to drain the old coolant.

I recall running some hose water through as a flush.

I refilled with coolant from WM, diluted 50 percent with water.

My setup (water heater is lower than coolant tank) will vent any air in the hoses by just leaving the coolant tank cap off, although I did install a vent in a hose that is higher than the cap (by 1 inch). It wasn't really necessary.

My old coolant looked a bit muddy, perhaps because of historical mixing of coolant colors. I recall Googling the significance of coolant colors, and the dangers of mixing brands, and encountering ambiguity, terror and hysteria.

Truth is, I mostly shrugged at ratios and full draining. If this is too cavalier an attitude I await correction.

My coolant is green now, and used to be red, and I feel much better about it.

 

[Frank Langer]

There is a difference between coolant for gas and diesel engines. Coolant for diesel is labeled as such and has different detergent stuff, available at many auto outlets.
Frank

 

[racushman]

My initial reaction is don't get overly concerned, it doesn't sound like this engine has exhibited any symptoms of cooling problems, obvious coolant in the oil, or oil in the coolant.

If it were my engine I would do the following:

1. Flush as much gunk out as you can with a hose
2. Flush the system -- Use one of the radiator flush products you can buy at the auto parts store/amazon, my guess is they are pretty much all the same... following the instructions on the bottle
3. Change the oil
4. Drain and fill with 50/50 coolant mix, run for ~5 hours or so. See if anything looks weird.
5. If all looks good, I'd probably still drain and refill one last time with fresh coolant (last step admitted belt and suspenders)

If there is a head gasket issue, the coolant will show up in the oil. If the crankcase oil hasn't been changed since you took the engine out, I'd take a sample and send it to Blackstone Labs in Indiana - they'll tell you if there's coolant in the oil. If you've already drained the oil, then I would run a sample after step 4 - it's a ~$25 investment.

Will be curious to hear what you learn. Probably this is just accumulated gunk from prior owner inattention, maybe someone mixed the red and green coolant types. My experience is most marine engine cooling systems are very robust, so I wouldn't worry too much about the flush.

 

[Kenneth K]

What does the source of all modern knowledge have to say about antifreeze for diesels?

First,​

What Is the Difference in Antifreeze for Deisel Engines & Gas Engines?

The difference between the antifreeze used in a diesel engine and that used in a conventional gas engine is that diesel antifreeze contains a special additive that protects against erosion on cylinder walls.

itstillruns.com

​

The difference between the antifreeze used in a diesel engine and that used in a conventional gas engine is that diesel antifreeze contains a special additive that protects against erosion on cylinder walls.​

​

Cavitation​

Cavitation occurs when high-pressure vapor bubbles that form in the cooling system attach to, implode and erode the wall of the cylinder in a diesel engine. Gasoline engines typically operate under lighter loads, have much lower cylinder pressures and do not require protection against cavitation.​

SCA​

Diesel antifreeze contains SCAs, or supplemental coolant additives. They prevent cavitation by forming a protective barrier between the cylinder wall and the vapor bubbles. Erosion affects the SCA coating instead of the cylinder wall.​

Additional Benefits of SCAs​

SCAs also neutralize acids, provide anti-foam protection and prevent scale and corrosion. The coolant system should be tested at least two times per year as part of engine maintenance. This is usually done with a refractometer or hydrometer.​

​

Next, ​

Cool News You Can Use: Light Duty Vs. Heavy Duty Antifreeze

A question that come sup frequently is what’s the difference between light and heavy duty antifreeze? KOST USA is here to help answer that. question.

www.kostusa.com

​

​

A question that come sup frequently is what’s the difference between light and heavy duty antifreeze? KOST USA is here to help answer that. question.​

​

Light duty engines are those in passenger cars or trucks, while heavy duty engines are those in large commercial vehicles like semi trucks, buses,or construction equipment. Both light and heavy duty antifreeze/coolant must protect against a range of challenges that can arise in a cooling system, but the main difference is protection against pitting cavitation: heavy duty formulations contain inhibitors that protect against cavitation while light duty formulations do not.​

​

You should NEVER use light duty coolant in a heavy duty engine, this will cause damage! However, a heavy duty coolant can be generally be used in a light duty cooling system without fear of harm.​

​

​

Pitting/Cavitation Corrosion - Many heavy duty diesel engines use replaceable liners that fit down around each cylinder to aid in serviceability. A type of liner called a wet sleeve liner fits down around the cylinder and comes into direct contact with the coolant. During an engine rebuild or overhaul, the liner can be replaced to allow the rest of the engine to continue in service.​

​

Cavitation corrosion occurs when vibration from the piston moving in the cylinder causes the wall of the wet sleeve liner to move, resulting in a microscopic reduced-pressure region, or air bubble, on the coolant side of the liner. The air bubble bursts, resulting in an explosion of 15,000 to 20,000 psi1 directed at the wall of the liner. This collapse occurs at a high frequency, and without proper inhibitors can drill holes through the wet sleeve liner,causing catastrophic damage to the engine.​

​

The ONLY way to protect a heavy duty engine from pitting cavitation is to use and maintain coolant with proper heavy duty additives, such as molybdate and nitrite. These inhibitors form a film over the metal protecting it from the effects of cavitation corrosion.​

​

Hmmm, what does that mean for my M-25? I know my diesel doesn't have "wet sleeve" cylinder liners, and it doesn't appear to pass the above stated test for a "heavy duty" engine. Guess I'll keep running the Prestone automotive formulation that's been in there since 2017.

What's in your engine?

 

[David Grimm]

Hit the link and view the second image that shows the back of the jug. Diesel approved. It's what I use as well as the previous owner.
One way to really get the system clean is to have an unidentified leak. Hmm. Bilge water looks a little funny and my coolant overflow tank is always needing to be topped off. After a month of hunting for the leak and 2 gallons of coolant I purchased a pressure tester. Found one of the pressure relief lines that ran under the cabin sole to the aft compartment had turned to jelly from the diesel it was exposed to from the now gone copper fuel line. Coolant system is spotless now! Lol

https://www.autozone.com/antifreeze-radiator-additives-and-windshield-wash-fluid/antifreeze-coolant/prestone-antifreeze-coolant-universal-premixed-dex-cool-compatible-10-year-300k-mile-protection-1-gallon/391379_0_0?cmpid=LIA:US:EN:AD:NL:1000000:GEN:71700000069889792&gclid=CjwKCAjwiLGGBhAqEiwAgq3q_m5tW2s2Zk8gpNW-7M4JtiVzwgP-TTV1d4enCRuN4ljYBBrQ41fhkBoCReUQAvD_BwE&gclsrc=aw.ds

 

[goldenstate]

What does the source of all modern knowledge have to say about antifreeze for diesels?

First,​

What Is the Difference in Antifreeze for Deisel Engines & Gas Engines?

The difference between the antifreeze used in a diesel engine and that used in a conventional gas engine is that diesel antifreeze contains a special additive that protects against erosion on cylinder walls.

itstillruns.com

​

The difference between the antifreeze used in a diesel engine and that used in a conventional gas engine is that diesel antifreeze contains a special additive that protects against erosion on cylinder walls.​

​

​

Cavitation​

Cavitation occurs when high-pressure vapor bubbles that form in the cooling system attach to, implode and erode the wall of the cylinder in a diesel engine. Gasoline engines typically operate under lighter loads, have much lower cylinder pressures and do not require protection against cavitation.​

​

SCA​

Diesel antifreeze contains SCAs, or supplemental coolant additives. They prevent cavitation by forming a protective barrier between the cylinder wall and the vapor bubbles. Erosion affects the SCA coating instead of the cylinder wall.​

​

Additional Benefits of SCAs​

SCAs also neutralize acids, provide anti-foam protection and prevent scale and corrosion. The coolant system should be tested at least two times per year as part of engine maintenance. This is usually done with a refractometer or hydrometer.​

​

Next, ​

Cool News You Can Use: Light Duty Vs. Heavy Duty Antifreeze

A question that come sup frequently is what’s the difference between light and heavy duty antifreeze? KOST USA is here to help answer that. question.

www.kostusa.com

​

​

A question that come sup frequently is what’s the difference between light and heavy duty antifreeze? KOST USA is here to help answer that. question.​

​

Light duty engines are those in passenger cars or trucks, while heavy duty engines are those in large commercial vehicles like semi trucks, buses,or construction equipment. Both light and heavy duty antifreeze/coolant must protect against a range of challenges that can arise in a cooling system, but the main difference is protection against pitting cavitation: heavy duty formulations contain inhibitors that protect against cavitation while light duty formulations do not.​

​

You should NEVER use light duty coolant in a heavy duty engine, this will cause damage! However, a heavy duty coolant can be generally be used in a light duty cooling system without fear of harm.​

​

​

Pitting/Cavitation Corrosion - Many heavy duty diesel engines use replaceable liners that fit down around each cylinder to aid in serviceability. A type of liner called a wet sleeve liner fits down around the cylinder and comes into direct contact with the coolant. During an engine rebuild or overhaul, the liner can be replaced to allow the rest of the engine to continue in service.​

​

Cavitation corrosion occurs when vibration from the piston moving in the cylinder causes the wall of the wet sleeve liner to move, resulting in a microscopic reduced-pressure region, or air bubble, on the coolant side of the liner. The air bubble bursts, resulting in an explosion of 15,000 to 20,000 psi1 directed at the wall of the liner. This collapse occurs at a high frequency, and without proper inhibitors can drill holes through the wet sleeve liner,causing catastrophic damage to the engine.​

​

The ONLY way to protect a heavy duty engine from pitting cavitation is to use and maintain coolant with proper heavy duty additives, such as molybdate and nitrite. These inhibitors form a film over the metal protecting it from the effects of cavitation corrosion.​

​

Hmmm, what does that mean for my M-25? I know my diesel doesn't have "wet sleeve" cylinder liners, and it doesn't appear to pass the above stated test for a "heavy duty" engine. Guess I'll keep running the Prestone automotive formulation that's been in there since 2017.

What's in your engine?

My local Yanmar dealer sold me this product.


Unfortunately it looks an awful lot like the pink diesel when dropped below the engine, making troubleshooting a bit more complicated.

 

[racushman]

Hmmm... I would have assumed it would be the yellow stuff.

Quick query of the group: my M25 should get red (long life) or yellow (regular duty) coolant?

 

[Frank Langer]

Hmmm... I would have assumed it would be the yellow stuff.

Quick query of the group: my M25 should get red (long life) or yellow (regular duty) coolant?

Only diesel coolant, not regular automotive coolant. The diesel coolant is available at most auto parts stores and I've seen it in purple and orange.
Frank

 

[David Grimm]

I go green. Just like the bottle from prestone says. "Gas/Diesel engine. (YES)

 

[David Grimm]

Wonder what came Standard in a 1980s Kubota? I would have to guess green.

 

[Kenneth K]

I go green. Just like the bottle from prestone says. "Gas/Diesel engine. (YES)

Yes, that was mostly my point in post #5. Unless you believe your engine is subject to pitting cavitation (ie, a wet sleeve cylinder, heavy duty diesel), normal automotive antifreeze, rated as suitable for "light and medium duty gas and diesel engines," is, well, suitable, and is likely what's been in there for the last 30 years.

The Prestone in my engine doesn't worry me a bit. I do continue to read warnings about mixing various colors of antifreeze, however.

 

[racushman]

Roger that, green not yellow (I think i was associating the color of the jug)