Flushing OAT coolant out of engine

[thinwater]

The re are 'extended life' coolants such as Cummins NOAT which are EH free, for which claims to be better with elastomers and hose materials.
These ccoolants are good for very long times and you'd probably only change them if they became contaminated, in which case a rinse might be a good idea.
https://www.cumminsfiltration.com/NOAT

Some of the other premium brands cite BASF inhibitors.

Boy, that's a great way to start a fight among coolant manufacturers! In part, this is because 2-EH is cheaper. But I have done lab work with both groups, have formulated both, and agree. The additives are FAR more expensive in modern coolants, as much as ~ $0.50/L, compared to just a few pennies nears ago. It's not all hype. The chemicals cost more.

But how do you know when it it contaminated with 1% seawater without lab testing? You cannot, and the lab work costs as much as the coolant. Thus, it is easier and safer to simply change every 1-2 years, without a flush, as a reasonable compromise. Salt water is a terrible thing for sleeved freshwater cooled engines, even traces.

[I'm not in the business anymore and don't have a dog in the fight.]

 

[Dull Spark]

I can see I've started a discussion between experts, but from my point of view:
-Halfords OAT is mono ethylene glycol with some special stuff added
-If in draining out that coolant, I leave even a small quantity of seawater contaminated stuff in the circuit, it will quickly damage the new antifreeze I add.
-If I flush out with tap water, I will get most of the crud out after a few flushes
-If a final flush is with demineralised water, so much the better for removing tap water salts
- If Halfords stuff is ok, then I'll just add a fresh batch of the same.

By the way, I don't think the Beta/Kubota engines at this size have cylinder liners.

Any disagreement from the team?
Thanks again.

 

[Dull Spark]

One last question: Can anyone recommend a coolant sampling kit? It would be useful to know when a change is necessary.

Many thanks.

 

[VicS]

One last question: Can anyone recommend a coolant sampling kit? It would be useful to know when a change is necessary.

Many thanks.

The only testers I know of are simple hydrometer testers that check the density of the coolant and give a percentage antifreeze and/or a freezing point figure.

eg https://www.halfords.com/workshop-tools/tools/hand-tools/laser-antifreeze-tester
or https://www.halfords.com/motoring/engine-oils-fluids/antifreeze/halfords-antifreeze-tester-meg

Of limited value especially if you top up with antifreeze if/when necessary but would indicate a major dilution with sea water.

If you have access to an analytical chemistry lab then an occasional test for chloride would enable you to keep a close, but OTT, eye on it

Even the extended life/ long life/OAT type of antifreeze should be changed at the recommended intervals when used in a marine engine due to the possibility of seawater contamination and not allowed 10 years service as you would in a car.

 

[RichardS]

-If I flush out with tap water, I will get most of the crud out after a few flushes
-If a final flush is with demineralised water, so much the better for removing tap water salts
- If Halfords stuff is ok, then I'll just add a fresh batch of the same.

That is exactly what I do using the Halfords OAT, except that I take 20L of softened water from my home down to the boat in a polykeg and use that for all the flushes up to the thermostat opening temperature, as determined by a hand on the coolant return. I used about 15 of my 20L flushing both 30HP engines.

Richard