Staight water vs Coolant Mix

[Sushibar]

I own a commercial fishing vessel with keel cooling, so the ambient sea water temp is 60 F. I have been running straight fresh water for years. Is this a good idea or is some coolant mix better.? It never has a chance to go below freezing or overheat as the cooling system is huge. probably 1200-1600 liters(approx 425 gals.) There are six engines feeding off the system. We overhauled the main engine at 25,000 hours ,with no coolant mix , there was very little cavitation wear on the liners.

What do you guys think, and why?

Thanks in advance for the responses.

 

[tom slick]

The only reason to run coolant in your case is for corrosion protection.

 

[bruce381]

I agree I would run a corrosion inhibitor something like a Nitrite that is avalible for heavy diesel use, not my bag someone can chime in that knows better.
bruce

 

[unDummy]

No additives? distilled water? what does the engine manufacturers recommend?

Little cavitation wear is too much. 'No wear' should be the goal.

Since you're at a consistent temperature, you don't need the boil over or freeze protection of antifreeze, or the cost of picking up 200 gallons of prestone.
But, I would think that an anti-rust/corrosion additive and pump lubricant should help.


For example, heres one of many that are available:
http://www.cumminsfiltration.com/en/products/en_prod_fg_cool_sca.shtml

You should research SCA additives for water-only cooling systems.

Coolant analysis is also an option. If the 'water only' system is working, the analysis will show it. If not, you'll have to adjust with additives or antifreeze.

 

[Sushibar]

didn't even think to get the water tested, but I have taken several oil samples.

D'oh! as Homer would say.

 

[onion]

What brand/model of engines are you running?

As a longtime heavy equipment mechanic... I say run antifreeze- the idea of running straight water through ANY engine makes me cringe. How could your cooling system compenents NOT be massively rusted/corroded? I think a proper mix of ANY antifreeze would be money well spent... but I'd specifically reccomend a 'heavy duty' ethylene glycol coolant with the nitrate/phosphate additives that you can check with test strips- most any heavy equipment or OTR truck place will sell it to you. Tell me what kind of engines you run and I might be a bit more specific.

 

[Sushibar]

3508 Caterpillar
6RBT-1 Isuzu
6SA-1 Isuzu
(3) DB-33 Daewoo

 

[NYEngineer]

The Cummins additive that was posted above works good, but my favorite is the Cat additive. If you don't have to worry about freezing, I would absolutely use one of the water treatments. One pair of engines that comes to mind was a customer that had a pair of 3412's (gensets). They were inside a building and cooled with heat exchangers, so the engine water never left the room. They used to get pretty nasty until I added the Cat additive. After that, the water was always nice and purple. I can't imagine how you didn't have more serious erosion on your liners. I've seen them go through and leak water into the oil pan.

 

[CBDFrontier06]

Even with such a huge cooling system, won't plain water still boil inside the engine when exposed to cylinder head temps? I would think an anti-boil and anti-corrosion additive would be desirable here.

 

[Sushibar]

I drained the water, it was in the system for 2 years since it was last drained. The water was a little brown, but mostly clear.

If any coolant is to put in what ratio should it be?

 

[onion]

Since you have a mix of engines, that won't neccesarily nail down one particular spec to stick with. Most any OEM antifreeze that's designed to protect engines from cavitation would work- it might be a good idea to go with the specs of your most expensive engine, and hope for the best on the rest of 'em. I've seen lots of different brands of coolant that reccomend a minimum 40% mix.

Also, I have no idea how old any of your engines are (I'm most familiar with Cummins, John Deere, and Detroit), but if any are still in warranty... then this cooling system thing would be a BIG issue. There's no way that ANY OEM is going to cover cooling system problems of any sort (including nasty stuff like cavitation) if you're running straight water.

 

[cmhj]

I've seen my share of "war climate" engines run on straight water. From what I've seen any mix is better than straight water due to the corrosion issues of straight water.

Most of the warm weather setups I've run were mixed 35/65, which is still good for about 0 F.

 

[Winston]

This is not like a car. You don't put in antifreeze just to be "safe." He does not have a chance to freeze, so he does not need antifreeze. He needs a corrosion inhibitor. The Cat product is probably appropriate. I would contact you supplier that provided the parts in your overhaul.