How to change coolant in Yanmar 2GM

[rortega46]

I've had a H28 for 2+ years without changing the coolant. I would appreciate it if someone could provide detailed steps of how this is properly done. Also, any suggestions on which coolant to use and where it's best to buy would be appreciated. I am unable to find step by step directions on either this site or in the Yanmar owners manual. I am sure once you've done this it is fairly easy.

Thanks in advance!

 

[Bill Roosa]

There should be at least one stop cock which drains the block. there might be more. After figuring out how you will catch the coolant, just take off the radiator cap and open the stop cock(s). Close the stop cocks and fill the engine with coolant. It is nothing special just use auto store anty. Don't fill to the very brim though. Once full leave the cap off and start the motor. bring it up to temp at idle topping off the fluid as needed. once the anty is at operating temp (steam coming off the surface in the radiator cap housing) put the cap on and let the motor run for a few minutes. Check for leaks at the stop cocks. Fill the over flow tank to the correct level (hot). Turn off the motor and let it cool. Check the overflow tank and refill as needed. Keep an eye on the overflow tank for a few motoring cycles.

 

[Steve Dion]

....and here is the product that our mechanic recommends.

http://www.jamestowndistributors.com/userportal/product.do?part=110101&BASE

Be sure to get the Extended Life Product. You will need to be sure that your entire system is flushed clear of ANY of the old stuff if you don't already have the extended life product in the system.

The extended life product is supposed to be good for at least 5 years.

 

[jorgefife]

Change coolant

....and here is the product that our mechanic recommends.

http://www.jamestowndistributors.com/userportal/product.do?part=110101&BASE

Be sure to get the Extended Life Product. You will need to be sure that your entire system is flushed clear of ANY of the old stuff if you don't already have the extended life product in the system.

The extended life product is supposed to be good for at least 5 years.

I too have a 2GM, but didn't know there was coolant in it! I recently changed the oil, and I remember it was the same make as Steve Dion suggested, but where does the coolant go? Is there a radiator on the engine? Stupid question I know, but what harm is there in asking?
Jorge

 

[Missinglink]

Coolant in Yanmar

The 2GMF has a heat exchanger where the raw water runs through one side of the exchanger and the coolant is in the engine and passes thru the other side of the heat exchanger. The 2GM the raw water circulates through the engine.

 

[Robert 47]

I am going from memory here, but I beleive there are 2 drain cocks with plastic drain tubes that hang down on the left side of the engine looking at it from the front. My Yanmar manual suggest there is another drain cock on the rear side of the engine. My Yanmar does not have one in that area. I use a plastic buckert of maybe a quart size and drain the antifreeze in it. Takes a little time. You may drain it down into the bilge, but then you would just have to clean that out as well. Follow the advice already given and you will have no problems. Stick to the green or orange stuff, stay away from the "pink" stuff, DexCool. As long as General Motors uses DexCool, I stay in business repairing head gaskets, upper and lower intake manifold gaskets on their cars and trucks.
I use a coolant addiative to boost the antifreeze and help lubricate the inner cooling system. They are available at any auto parts store. Hope this helps you out.

 

[Steve Dion]

I too have a 2GM, but didn't know there was coolant in it! Jorge

Jorge: Not all GM engines are fresh water cooled. I believe that the engine ID will have an "F" in the model number for an engine that uses anti-freeze. I would also doubt that the "F" engines would have an expansion tank.

 

[Steve Dion]

Stick to the green or orange stuff, stay away from the "pink" stuff, DexCool. As long as General Motors uses DexCool, I stay in business repairing head gaskets, upper and lower intake manifold gaskets on their cars and trucks.

Robert: We have heard this before about GM automobiles, but I have never heard any issues with Yanmar's having this type of a problem related to DexCool. Yanmar recommends DexCool for their current engine lineup as well as their older model lines.

The only issue I know about (and I surely don't know much about anything) is the issue with mixing the old and new products can ture your system into "MUCK".

We had ours flushed & refilled with the Rotella version of DexCool 3 years ago and it has been fine. I suppose that is no indication that it will be fine in the future.

 

[s sauer]

Coolant for 2GM20F

We have the 2GM20F Yanmar in a 28.5 and changed to Yanmar's own orange antifreeze several years ago. We have had one of those $800+ repairs due to DexCool attacking intake manifold gaskets in our Pontiac so I used Yanmar's pre-mixed product instead of DexCool. However, I did a complete flush & 3 rinse outs of the 'green stuff' from the Yanmar before changing the antifreeze type.
For a 2GM20F, you may need to 'burp' the air out of the top of the engine as an air bubble can form under the thermostat and your overheat alarm will sound because the T-stat will not open. I solved the problem by bleeding the air out of the system, by loosening the hose clamp on the upper hose from the front of the engine to the water heater. Don't bleed it after the system is already hot and under pressure.
There is an expansion tank on the antifreeze side of the system adjacent to the 'radiator cap' coolant fill riser in the sail locker. Make sure you take that off and clean it out as well.

By the time you've done the flush & rinses, you will be an old hand at burping the air out. The 2GM20F system with water heater loop takes slightly more than a gallon of antifreeze. I expect you could also pull the thermostat and put it back in after the flushes.

 

[Mike Culik]

it is a good time to look at the hose conditions!

I had no clue what maintenance was done by previous owners so I made a day project of it and replaced all the hoses, belts and then the antifreeze on my 2GM20F

 

[Steve Dion]

Mike:

That is an excellent idea. If you have changed all of your hoses, belts, and filters you now have a good base point for an annual maintenance review.

 

[rortega46]

Thanks to everyone for the great advice. I plan on changing the coolant after Mardi Gras and will think about changing all hoses sometime soon. The detailed instructions will be very helpful. Keys seem to be drain and flush 3 times then go with green or orange extended life coolant. Looking forward to learning how to burp. Does anyone know how much coolant I will need?

 

[Steve Dion]

More than 1 gallon and less than two. I suggest that you get the pre-mixed (about $15-20 gal).

 

[Robert 47]

Steve you are right. I am just over causious. I am referring to the rubber "O" rings on the heat exchanger of the 2GM20 that could be damaged by DexCool. I own an automotive service center, and I see GM cars come in with gaskets leaking alot. If Yanmar suggest to use their brand of DexCool, I am sure it is good stuff. I wouldn't think they would recommend it if it didn't provide the service needed. You are also dead on about not mixing the two types. I have learned quite alot of information from you and other sailors on this web site, so don't say you don't know much.
Guess rorgeta46 will get his antifreeze changed without any problem. I would follow Steve's advice about the hoses, and belts. I carry extras on board so if I spring a leak or through a belt I have what I need. This is cheap insurance compared to the cost of tow. Not to mention floating down river into a oncoming barge without any iron jenny power.

 

[gary_y]

We have the 2GM20F Yanmar in a 28.5 and changed to Yanmar's own orange antifreeze several years ago. We have had one of those $800+ repairs due to DexCool attacking intake manifold gaskets in our Pontiac so I used Yanmar's pre-mixed product instead of DexCool. However, I did a complete flush & 3 rinse outs of the 'green stuff' from the Yanmar before changing the antifreeze type.
For a 2GM20F, you may need to 'burp' the air out of the top of the engine as an air bubble can form under the thermostat and your overheat alarm will sound because the T-stat will not open. I solved the problem by bleeding the air out of the system, by loosening the hose clamp on the upper hose from the front of the engine to the water heater. Don't bleed it after the system is already hot and under pressure.
There is an expansion tank on the antifreeze side of the system adjacent to the 'radiator cap' coolant fill riser in the sail locker. Make sure you take that off and clean it out as well.

By the time you've done the flush & rinses, you will be an old hand at burping the air out. The 2GM20F system with water heater loop takes slightly more than a gallon of antifreeze. I expect you could also pull the thermostat and put it back in after the flushes.

Regarding burping the system, the shop manual suggests removing the thermostat and filling through there. This should avoid the burping, but cost you a gasket. Also, my engine has a petcock valve on the outlet of the water pump which could be used bleed the system. I suspect it was not original, but something a previous owner added.

 

[Bill Roosa]

blurping???? You guys do know that once the engine comes up to temp the thermostat opens and lets any remaining air out. If you follow the proper procedures blurping is not needed.
fill the engine with coolant, turn it on and bring it up to temp with the "radiator cap" off, keep the coolant toped off till you see steam coming off the coolant surface indicating that the thermostat has opened up, (probably see a drop in coolant level at this time due to residual air escaping), top off the coolant and replace the cap. check for leaks.

 

[rortega46]

Well I picked up some Rotella extended life coolant like you guys said. Yesterday went to the boat removed the engine access panels and was ready to start changing the coolant. Problem from the get go is I can't find the drains. The owner's manual is no help. Looking at the engine from the bow I see what looks like a drain cock on the left side of the engine. It is higher than I expected and seems to be for the heat exchanger. Can anyone be specific about what the drains look like and where they are specifically located? Pictures would be great if possible.

 

[rortega46]

Is it possible the 2gm20 only has one drain cock? This is all that is shown in the owners manual, but the manual's diagram shows it on the right side looking back from the bow.

 

[gary_y]

Is your engine really a 2gm20f (closed cooling system) or a 2gm20 (raw water cooled)? I'm looking at the service manual and it implies the raw water cooled engine has one drain on block, and the 2gm20f has two to drain coolant from the block and heat exchanger.

 

[Jake N Eggs]

In your picture, just to the right of the fuel filter, the fitting looks like it has a knurled piece on the end. This could be the drain. Try and turn the knurled piece counter-clockwise. The coolant may drain out the middle of the fitting.