An idea perhaps .. for flushing coolant

[Rick9619]

I was sitting around after a great day of sailing still pondering a coolant change on my 3GM30F, when after a boat drink or two I hit on a idea. My 336 has the six gallon hot water heater in the cooling circuit so I thought... what if you disconnected the return line from the water heater to the engine and then used the engine itself to flush the coolant. Feed that line into a container and the dock hose into the fill hole for fresh water. Would that work? I would have to run the engine to get the thermostat to open but then could drain the coolant, flush it, without the usual problem of opening petcocks and not really getting the coolant out. I was considering changing to the orange stuff and all I hear is that you cannot mix with the conventional type. Just an idea but what do you all you experts think? Remember it was after a drink or two back at the dock CheersRick

 

[Jim Rushing]

Ouch!

Just remember that you are now dealing with really hot liquid instead of something cool. Draining the coolant is a pain, but it should be done at least every other year. The problem with the old coolant is that the corrosion preventing chemicals start to break down after a while.

 

[seadaddler]

Remove Thermostat

Sounds like a good idea but just remove thermostat and not deal with the hot coolant.

 

[Rick9619]

Changing coolant

Seadaddler, that is a good thought. Just pop out the thermostat and then since engine is cold, no hot coolant and you wouldnt have to cycle any water through initially. Of course replace with new gasket. That would give you an accurate measurement of how much coolant to put back in. I dont think Yanmar includes the heater circuit in its spec.CheersRick

 

[Liam]

How do you do it normally?

Can anyone give a rundown on how to change the coolant? I have been putting this off and should really do it but never have. I don't think I will try the method described above. How do "mechanics" do it?Thanks.

 

[Rick9619]

Changing the coolant

Liam, you open the petcocks and let them drain. Drain, drain the coolant from the filler bottle. All the while be very careful to not get any on engine! Very corrosive. Then you close all, fill it up with water, flush, repeat, then top off with the appropriate coolant. Its just hard to get a really good flush especially if you are switching to the orange coolant. The above was an idea. I havent tried it either, just thinking outside the box.CheersRick

 

[Liam]

Thanks Rick

I also have a 3gm30f that is plumbed to the water heater. Seems to me like it will be really hard to get all the coolant out of the entire system as well as all the hoses to the water heater.Also, I had attended a Yanmar engine seminar and they said to only use BLUE coolant. They said that the pink will corrode the water pump whick on that engine is made of aluminum alloy. Have you heard anything about that?Thanks again, Liam.

 

[Rick9619]

Flushing engine coolant

Liam, I havent heard anything about the pink coolant although I havent really researched it. It seems the new orange, and I dont have it sitting in front of me, is the environmentally friendly type and easier on the engine too. Only thing is I was told you want to make sure to get the old stuff out because they dont mix well. Perhaps someone else can chime in here. I got that info from Torrenson Marine. Pretty smart guys.CheersRick

 

[chuckwayne]

the orange, silicate free coolant is the

recommended coolant from Yanmar. you must completely flush the old green stuff from the engine or the mixture will turn to sludge-very bad! Rick's basic idea is good, but you should also drain thru the petcocks and keep on reeating the flush until you are sure you got rid of all the old stuff. It would also be good to stop the flush, run the engine to heat it up so the thermostat opens, then repeat your flush.

 

[NYSail]

Flushing chemical

when I flushed my old cars, I would drain the old stuff, take out the thermostat, add some radiator flush and top off with water. let it run for 10 mins or so drain, flush with fresh water, drain repeat as necessary.Is there a product that yanmar says is ok for this.Thanks all