Change coolant on Yanmar 3GM30F

[dmksails]

The boat I've purchased has a Yanmar 3GM30F and the coolant looks pretty bad. I've the service manual, but it only contains a few lines basically saying to drain and refill. I also have a heat exchanger that provides cabin heat when the engine is running.


What should I do to make sure I get all the old coolant out?

Do I need to worry about airlocks?

[gamayun]

Just open the hose between the engine and the cabin heater (mine goes to a water heater) and that should be low enough that everything drains. Since the coolant is hazardous waste, it also needs to be properly disposed. You should have a local facility that will take it. Just don't co-mingle it with oil or something else. After all is done and you've refilled, run the engine/heater/etc and then check the coolant level. It's possible there are bubbles in the system so you'll want to check a few times to make sure all is topped off well. The overflow container usually remains around the half-full mark when my 3GM30F is cold.

[a64pilot]

I installed a Prestone flush kit in the line of the water heater and completely flushed the engine like you do an automobile.
Draining and refilling doesn’t get the rust etc out, it just removes the coolant.

Anti freeze greatly diluted isn’t toxic and breaks down very quickly.
I’m sure people in California will say the horrors, but that the truth.

Think of how many gallons are used to de-ice airplanes in the North every day, and airports haven’t been declared toxic waste dumps to my knowledge.

[gamayun]

Yup, my bad. EPA has not designated coolant as a haz waste product but many states, including us enviro Nazis in California, have. Everyone is going to do their thing (in good conscience or in ignorance, whatever). That's just the way things are, but I will continue to try to educate and people can decide to adopt good practices or not. It just may also be good to remember our not so distant past when the Cuyahoga River burned from the dumping of contaminates and San Francisco Bay was so polluted, people held their noses going over the Golden Gate Bridge. Most companies don't do that anymore. Maybe individuals might think about the same...

[a64pilot]

It was one of the very, very few things in the Army that we could allow into the washrack.
It degrades in a week or so, into what I don’t know, and if not very diluted, it can kill a dog etc that drinks it.

However if you have rust etc., you going to have to flush the system, only very rarely do you need chemicals, but flush until nothing but clear water runs out, run the motor and drain to ensure it’s still nothing but clear water.
Remove the overflow tank and with a rag and bottle brush clean it out well too. Then you can add fresh coolant shooting for a 50% ratio for a good mix of cooling effectiveness and corrosion protection.
Pure water is the best coolant, but causes corrosion of course.

[Chuck Hawley]

Originally Posted by a64pilot

I installed a Prestone flush kit in the line of the water heater and completely flushed the engine like you do an automobile.
Draining and refilling doesn’t get the rust etc out, it just removes the coolant.

Anti freeze greatly diluted isn’t toxic and breaks down very quickly.
I’m sure people in California will say the horrors, but that the truth.

Think of how many gallons are used to de-ice airplanes in the North every day, and airports haven’t been declared toxic waste dumps to my knowledge.

I think you may be mixing up two different types of antifreeze: propylene glycol (C3H8O2), which is used to winterize boats and de-ice aircraft, and ethylene glycol(CH2OH)2, which is used in automotive cooling systems. One is fairly benign and the other is extremely toxic.

From Wikipedia:
Propylene glycol is frequently used as a substitute for ethylene glycol in low toxicity, environmentally friendly automotive antifreeze. It is also used to winterize the plumbing systems in vacant structures.

Ethylene glycol is highly toxic, with an oral LDLo = 786 mg/kg for humans.[21] The major danger is due to its sweet taste, which can attract children and animals.

Chuck Hawley

[Jeanneau 45.2]

Whether radioactive, toxic or otherwise the unnecessary and intentional discharge of any foreign matter into our waterways is ... I'll just leave it at "irresponsible".

As to how to drain the Yanmar fresh water cooling system, I agree the shop manual is short on details. I hired a Yanmar shop to do the first flush of my 4JH3-TE, and there is a very easy and mess free way to completely drain the block and collect all the toxic (see Chuck's post) waste antifreeze.

There are four (4) petcocks on my engine (port, std, aft, fore) with nipples to accept PVC tubing. Purchase an engine block cooling tester (for example: Auto Zone part number 27069). Install the pressure tester on the radiator fill neck, fit the tubing over the nipple and open the first petcock and use the pressure tester to apply pressure to the coolant loop and catch the coolant in a resealable container (so you can transport it to the auto shop for recycling, just like you do for used engine oil). Close petcock #1 and repeat for the remaining petcocks. You will virtually empty the coolant passages of the block and have zero antifreeze ending up in your engine pan, bilge and our waters.

I think you'll find filling the engine with new coolant and removing all air pockets in the cooling loop will be the difficult part. I'll leave that to others to advise.

Peace out.

[Gripfast]

I normally do most of my engine maintenance but decided to let the yard do my 3GM30F. I was worried about some rusty water stain on the engine. I had about 900 hours on the engine and thought the engine coolant pump was leaking.
It turned out to be not related to the coolant system but was time for a flush. They pulled my heat exchanger and had it throughly cleaned. They engine heat exchager now makes much hotter water more quickly than it did before. Engine cools better as well.

I am confused because the yanmar mechanic said that there are no zincs on the engine. Which maybe why my electric water heater plugged up and had to be replaced a couple years ago.

Sorry to hijack the thread, but I wonder if others with a 3GM30F have zincs?

[a64pilot]

Many Yanmars don’t have zincs, my 4JHE for example does not

[Wotname]

Originally Posted by a64pilot

Many Yanmars don’t have zincs, my 4JHE for example does not

Yes, this is correct. AFAIK, most (all?) smaller coolant cooled Yanmar engines do not have zincs as the Yanmar heat exchanger is cupronickel and the block/head is cast iron. Zinc does not add any real protection. If the cooling system is modified by the addition of hot water systems etc, then all bets are off.

Of course, raw water cooled Yanmar engines do have zincs and these must be replaced as required.

[Dulcesuenos]

Originally Posted by Wotname

Yes, this is correct. AFAIK, most (all?) smaller coolant cooled Yanmar engines do not have zincs as the Yanmar heat exchanger is cupronickel and the block/head is cast iron. Zinc does not add any real protection. If the cooling system is modified by the addition of hot water systems etc, then all bets are off.

Of course, raw water cooled Yanmar engines do have zincs and these must be replaced as required.

Sorry incorrect information here, I have found a zinc on the starboard side of every yanmars 2gm20f I have worked on it is just above and forward of the lift pump. I'd be surprised if the 3gms didn't have it as well. Even the yanmars dealer said there wasn't one and I proved them wrong. I'm not saying wears fast as it is in the antifreeze but they do have them from the earlier ones to the last few they made I've pulled a few and they were still serviceable after a few years . I've seen them on at least 6 different 2gm20f's

[Wotname]

Originally Posted by Dulcesuenos

Sorry incorrect information here, I have found a zinc on the starboard side of every yanmars 2gm20f I have worked on it is just above and forward of the lift pump. I'd be surprised if the 3gms didn't have it as well. Even the yanmars dealer said there wasn't one and I proved them wrong. I'm not saying wears fast as it is in the antifreeze but they do have them from the earlier ones to the last few they made I've pulled a few and they were still serviceable after a few years . I've seen them on at least 6 different 2gm20f's

Thanks for providing the correct information. One thing I really like about CF, is that very little erroneous information goes unchallenged and that way we all learn

So I will update my previous statement to AFAIK, some smaller coolant cooled Yanmar engines do not have zincs as the Yanmar heat exchanger is cupronickel and the block/head is cast iron

The couple of 2GM20F engines I was familiar with had the zinc plug in the position you described but without the anode fitted. Perhaps it had been fitted in the past or removed and never replaced or perhaps never fitted.

FWIW, the 3YMxx engines do not have anodes in the cooling system (checked the manual before I posted ).

[ggray]

Originally Posted by a64pilot

I installed a Prestone flush kit in the line of the water heater and completely flushed the engine like you do an automobile.

Do you need to remove the thermostat to do it this way? And how can you be sure that all parts of the "loop" get flushed?

It's just about time for me to do this again, so looking for the best--hopefully easiest-- way. The last time, I filled w/ water, ran the engine, and drained, and repeated several times. I was changing antifreeze types then, and didn't want to risk mixing, but this time I want to run a radiator flush/cleaner, so want to get it all out.

[a64pilot]

You don’t have to remove the thermostat, there is always a bypass to a thermostat, Although it can be very low flow.
Drain your coolant first for disposal, then turn on the hose, wait for water to flow out of the overflow and wait until it is nothing but clean pure water.
I crank the engine at this time and let it idle so water flow is established throughout the engine and run until it’s clear, clean water.

I have removed a thermostat before on a nasty engine, but don’t think you have to.

Following the instructions provided with the flush kit seems to work.
Just of course our water heater hose is the normal car heater hose, so you don’t have to turn the heater to full

[four winds]

Many people think the 3GM30 on came in the F version, including parts dealers.

It came in raw water and fresh cooling versions, though I think most were fresh. And they make or made a conversion kit from Yanmar to convert raw to fresh. The dealer don't remember this, it was too long ago anyone did conversion. Also, dealers may thnk the raw pump is the same on 2gm20, 3gm30, and 3gm30f. Well they fit all, but they are different just the same.

Anyway, my F version has a flat-faced plug above the lift pump. Not the freeze plug, a threaded plug with a square drive hole in it. The parts manual shows it as number 14 on the pic.

Number 15 on the raw engine block pic it shows the zinc instead.


I suspect the raw version was sold with a zinc, and the fresh with the plug.

Conversions had the zinc left in place (why not). And others added a zinc thinking it was remiss of Yanmar not to include one.