Flushing Yanmar 4JH2E Coolant

[seabum]

Hello All, I'm new to engine maintenance. I could use some some help to make sure that I have this coolant flushing procedure right before I launch into it.

It was suggested that I drain the old coolant, fill with "Flush", run the engine for 1/2 hr, drain, fill with plain water, run engine again, drain and then repeat if still dirty or smelly; otherwise finish by filling with diluted coolant.
Does that sound right?

Questions:
how long will it take for the engine to cool down enough for me to drain the flush or water without burning myself or melting the plastic jug I'll drain it into? What "smell" would I smell if it's not clean enough yet? Any other caveats I need to be aware of?

Thanks so much for your help!

[delmarrey]

Without knowing how many hours on the motor I would be cautious about using a flush chemical. It could eat thru the heat exchanger unless you know when the last time the exchanger core was serviced.

I wouldn't worry about smell. Just make sure all the flush chemical is out. Run three different rinses.

When the temp gauge is below 120 it should be safe to remove the cap.

[seabum]

Originally Posted by delmarrey

Without knowing how many hours on the motor I would be cautious about using a flush chemical. It could eat thru the heat exchanger unless you know when the last time the exchanger core was serviced.

I wouldn't worry about smell. Just make sure all the flush chemical is out. Run three different rinses.

When the temp gauge is below 120 it should be safe to remove the cap.

Thank you, delmarrey! The engine has about 1690 hours on it. I do not know anything about the heat exchanger service record. The bottle of flush says to dilute by 1:10 of water. Hopefully that helps dilute the strength enough. And thank you for the temperature guidance.

When you say 3 different rinses, do you mean 3 all-water rinses after the flush? And do I need to run the engine for 1/2 an hour with each rinse?

This is all very helpful. Thanks!

[delmarrey]

Yes, all water rinses. And you just need to run it up to temp to open the thermostat.

[seabum]

Thanks so much. This is great!

[a64pilot]

What prompted the flush? Are there any operational issues or just the coolant is old and needs to be changed? Is there rust in the coolant?

[thinwater]

(I have worked in the coolant industry for 25 years and have one long-life patent to my name)

Flushing chemicals are an incredibly bad idea unless you have a very serous clogging issue, which you should not have. You are far too likely to leave aggressive chemicals in the system, which will do damage over the years far exceeding any problem you think you have.

The best procedure is to simply change the coolant with a fresh dose of what was used before. If you must change formulations, flush in between with 2 changes of tap water. Any dillutions should be with deionized water, and the concentration should be 50%. Use a heavy duty (diesel rated) coolant.

Don't do it!!

[lancelot9898]

Some years ago after taking to a diesel mechanic, I switched from the trypical anti freeze to the heavy duty diesel stuff. I was careful to fully purge the system of the old stuff since I was switching. Come to find out later that my Perkins 4-108 had dry cylinder sleeves and as such did not really require the heavy duty stuff that a wet cylinder sleeve should use. I will continue using the heavy duty Prestone since I believe there is more rust inhibitors in it plus I don't want to flush the system again.

[delmarrey]

BTW Yanmar recommends a special grade of antifreeze. The Texaco product Code #7997 & 7998 or Havoline/Chevron #7994.
I ended up at a NAPA store to find the right stuff.

Here's the Operational Manual. Goto page 36
http://www.yanmar.fi/content/downloa...01_18DEC06.pdf

[seabum]

Originally Posted by a64pilot

What prompted the flush? Are there any operational issues or just the coolant is old and needs to be changed? Is there rust in the coolant?

Hi a64pilot,
No, we are not having any issues. We've had the boat for 3.5 yrs and I don't know when the coolant was last changed. Honestly, I just read somewhere that that's what you need to do. However, there is slight evidence of some rust in the coolant.

[seabum]

Originally Posted by thinwater

(I have worked in the coolant industry for 25 years and have one long-life patent to my name)

Flushing chemicals are an incredibly bad idea unless you have a very serous clogging issue, which you should not have. You are far too likely to leave aggressive chemicals in the system, which will do damage over the years far exceeding any problem you think you have.

The best procedure is to simply change the coolant with a fresh dose of what was used before. If you must change formulations, flush in between with 2 changes of tap water. Any dillutions should be with deionized water, and the concentration should be 50%. Use a heavy duty (diesel rated) coolant.

Don't do it!!

Thanks, thinwater, I hear ya! For coolant I bought Prestone's yellow longest-lasting, compatible with any color, coolant. I think what I have now in there is a pink one. I THOUGHT the Prestone stuff was going to be pink (the fellow at the store thought it was...but there you go). I have, in fact, diluted it already with distilled water, amazingly something I thought of on my own.

[seabum]

Originally Posted by delmarrey

BTW Yanmar recommends a special grade of antifreeze. The Texaco product Code #7997 & 7998 or Havoline/Chevron #7994.
I ended up at a NAPA store to find the right stuff.

Here's the Operational Manual. Goto page 36
http://www.yanmar.fi/content/downloa...01_18DEC06.pdf

Hi delmarrey, thank you. Would this apply for a 4JH2E engine, too? Somewhere I read that the Prestone antifreeze for diesel (the longest-lasting, all-color compatible stuff) is an OK substitute for Texaco.

[delmarrey]

You can't go by color anymore. There are many grades by the same manufacture. You need to go by the code #s. Some are for cast iron, some for aluminum and some for brass. In the old days brass and iron was about the only thing in cooling systems. Now there is aluminum. And in Yanmar there are all three.
With the wrong coolant one can create a chemical relation that will damage one or more of the metals.

I had a Pathfinder (VW) motor, that some one had just put in a generic coolant just before I bought it. Within a year I had to replace the aluminum water pump and thermostat housing. It had eaten it from the inside. When I drained the coolant a whitish mud came out the last bit of it. I let it settle for a week and skimmed off the top coolant. The mud was aluminum oxide.

a Lesson Learned about buying someone else's work and grades of coolant.

[thinwater]

Originally Posted by delmarrey

BTW Yanmar recommends a special grade of antifreeze. The Texaco product Code #7997 & 7998 or Havoline/Chevron #7994.
I ended up at a NAPA store to find the right stuff.

Here's the Operational Manual. Goto page 36
http://www.yanmar.fi/content/downloa...01_18DEC06.pdf

-----

The Cheron product is Dexcool. Any store will have it. Not a heavy duty diesel product, but it isn't really a heavy duty engine. If the manufacturer is good with it, that's enough.

The Texaco product is a heavy duty variation. The better choice. Might have to look harder for that. In this case, it is the nitrite-free that is important to them; there aer other LL heavy duty nitrite free coolants.

http://www.taligentx.com/passat/info...fe_Coolant.pdf

[seabum]

Originally Posted by thinwater

-----

The Cheron product is Dexcool. Any store will have it. Not a heavy duty diesel product, but it isn't really a heavy duty engine. If the manufacturer is good with it, that's enough.

The Texaco product is a heavy duty variation. The better choice. Might have to look harder for that. In this case, it is the nitrite-free that is important to them; there aer other LL heavy duty nitrite free coolants.

http://www.taligentx.com/passat/info...fe_Coolant.pdf

Thanks so much for all of your input!