Flush Or Not Flush

[BigEasy]

I am changing coolant on my Yanmar 3YM30 diesel. Converting from green to red extended life coolant. I have flushed with fresh water 3 times and have eliminated all traces of green coolant. On the third flush, getting a slight orange color that probably indicates that there is a bit of rust/scale in the system. Should I continue to flush with fresh water or should I use something like Preston radiator treatment in attempt to "descale" the system. I am concerned that Prestone might damage the heat exchanger or water heater coils. No problem with overheating---just time for routine maintenance.

 

[ggrizzard]

Did you/have you cleaned the heat exchanger manually?

 

[Gunni]

BigEasy; In my opinion it is more important to look after concerns regarding cylinder pitting and frequent coolant change outs. That means running a coolant in conformity with ASTM 6210, and changing it regularly. I believe further flushing is not warranted in your situation.

 

[thinwater]

If you have maintained the coolant properly, flushing is NEVER regular maintenance.

The greatest coolant risk with marine diesels is not the coolant type, or weather you flushed it 3 times, but whether seawater is leaking in. the condemning limit is only 1 part seawater per thousand parts water. Test for chloride (not chlorine--different), if you want to know.

Make-up water should be of the same quality you use in a battery, not tap water (from ASTM spec).

 

[BigEasy]

GGrizzard, No I have not cleaned the heat exchanger. Didn't really plan to; I know that I probably should do it, but
the motor has low hours and no problems whatsoever. Would have to order parts and I am ready to finish
this project tomorrow. Will get to the heat exchanger on next flush. As far as cleaning the exchanger, I
have "rodded out" previous heat exchangers with a 22 rifle cleaning brush. I have recently read that it should be
professionally cleaned by a radiator shop that has an ultrasonic bath.
Gunni, Yes, I believe I will do two distilled water flushes tomorrow AM to rid the system of tap water that I used
to flush out the old coolant and call it a day. Yanmar recommends Havoline extended life coolant and
that's what I will be using; a 50/50 mix of coolant and distilled water.

Thanks to both of you for the advice.

 

[BigEasy]

Yanmar recommends changing the coolant every two years, so that is regular planned maintenance in my opinion.
I am converting from green coolant that the previous owner used to Havoline extended life coolant that Yanmar advises, thus the need to thoroughly flush the system. I was not about to use distilled water to flush out all of the old coolant. Used tap water under light pressure. I will be using distilled water to flush out the tap water and of course in the coolant mix. There is no evidence of seawater leakage as the coolant recovery tank levels have remained the same for 3 years.

 

[JamesG161]

If you have maintained the coolant properly, flushing is NEVER regular maintenance.

I check clarity, level, and pressure checker once a season.
In addition...
I check the fluid for salt water with these cheap pool test strips.

https://www.amazon.com/Aquachek-561...297085&sr=8-6&keywords=salt+water+testing+kit

Dip one test strip in new fluid (extra from same fill container) against a 2nd strip from my engine. I tested 2 once of Antifreeze and 2 drops of salt water mixture. Strip picked the salt up.
Jim...

PS: I do the same engine and gear oils.

 

[BigEasy]

Jim,
Thanks for the heads up on the test kit. Never have used it; however, will do on the next oil change and coolant check.

 

[Scott B]

BigEasy; In my opinion it is more important to look after concerns regarding cylinder pitting and frequent coolant change outs. That means running a coolant in conformity with ASTM 6210, and changing it regularly. I believe further flushing is not warranted in your situation.

I too have the 3YM30 and will be changing the coolant this year. What concerns about cylinder pitting should I be looking for. Haveoline is difficult to find up here, but have found Shell Rotella Ultra ELC Nitrate free. It is ASTM 3305 and 6210.

 

[Gunni]

The concerns are in regard to the duty load of a marine diesel, and the cavitation of coolant against the thin cylinder walls of the Yanmar. If your coolant meet ASTM 6210 then I would say your best policy would be regular changes. I decided to change to a PG based coolant because of concerns that it circulates through my potable water system.

 

[Bob 04 H260]

On my Yanmar I did a "reverse" flush and tiny pieces of impeller rubber came out. I used very low pressure from the dock hose going into the hose that is normally connected to the mixing elbow.
Bob