Coolant flush and refill 6CTA.

[Bill Receski]

I have a new to me 6CTA 420 Diamond. 2600 hours. I think they told me a M2??? I would like to do a coolant replacement. Can anyone give me a few tips such as where is the drain plug and what is the recommended procedure. Also what coolant is the best replacement.

Thank you for any input on this,
Bill

Topic

[Kevin]

Coolant flushing required? 6CTA 430

Hi All,

Saw this thread and it has great info!

Quick additional question. During our sea trial, I watched the owner pour green coolant ethylene glycol into orange coolant on the port engine. It was only a slight amount to top up the coolant recovery bottle which was much lower than the starboard engine.

I know this could be bad as if one was OAT and the other was EG it could cause gelling. I know the coolant was changed in Sep of 2020 on both engines and I have the invoice for 16 gallons of coolant, but it doesn’t call out type. Assuming it was EG but the orange/red version.

I am about to replace the port with ES Compleat Blue, and the starboard is still in good shape so just changing the filter for annual maintenance and will probably swap to blue next year as total time on the coolant is just 265 hours (starboard engine was replaced).

Is there any flush technique, or will just draining the coolant on the port and changing the filter be good enough?

If not, I assume I could drain and fill with distilled water and run the boat to get it up to temp and then drain and fill with the ES Compleat Blue? Is that overkill?

Thank you in advance for any info!

Best,
Kevin

[Bill Receski]

Thanks

Great info guys thanks.

[William Walter]

Cooler fill

Just at the dock so far. Last time I did this it did take a couple of runs at temperature but didn’t have to burp it as it sucked it up from the overflow reservoir.

[Rob Schepis]

Bill, on your cap loose running was that at the dock or under load? She’ll need to get to tstat opening temperature a time or two to purge and level out.

[William Walter]

Coolant

Just drained the coolant on mine and used the fitting by the water filter to do it.Worked well but the trick is getting it all back in without any air getting into the system.pour as slow as you can and if you have a pet valve at the top of the heat exchanger open that as you do.Even doing that I’m still about a gallon shy of what I took out .Ran the engine with the cap loose and am still half a gallon short but think by repeating the process it should work out.Bill

[Jay Becker]

Drain petcock is under the oil cooler housing. I use Fleetguard ES Compleat premixed blue coolant. Fleetguard part CC2825.

[Steve Lewis]

Tony’s Tips

https://www.sbmar.com/articles/cummins-6cta-8-3-coolant-drain-location/

Check out Tony’s Tips. There is a wealth of info in there for your benefit.

[Author]

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