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I'm cautiously optimistic my second descaling mission cleared enough of the blockage to maintain engine temperature under load. My current flushing system avoids the new impeller I just installed and mitigates the need to hook up a water source to the mixing elbow to keep the exhaust cool while the descaler circulates in the closed loop.
#Yanmar 2gm cooling pump full#
Why not close the loop of the cooling system, run it full of descaler until nearing overheating, shut down and let it perc until cold, repeat a couple of times then flush it out? I'd appreciate any wisdom on what I could be overlooking. I'm considering another descaler flush in an attempt to avoid pulling the head off and manually cleaning the water passages in the block which is going to require at least 40 more hours of YouTube tutorials before I have the confidence for that job. The problem with my blocked water passage hypothesis is that the descaler was forced through the block and the flow didn't seem to be impeded. Visually inspected all of the hoses from the thru hull through to the lift muffler Installed a new mixing elbow and cleaned the 90 degree elbow that feeds it with raw water Installed a new impeller įlushed the block with Rydlyme For this reason, I assume the blockage is in one of the water cooling passages in the block. I've worked through the entire raw water system to come to this conclusion: From cold, the engine starts perfectly, produces a steady stream of water out the back end with the exhaust and when it starts to warm up and the thermostat actuates to force cooling water through the block water flow diminishes completely. I expect you could also pull the thermostat and put it back in after the flushes.My Yanmar 2GM is winning in the battle of trying to melt itself down under load. The 2GM20F system with water heater loop takes slightly more than a gallon of antifreeze. Make sure you take that off and clean it out as well.īy the time you've done the flush & rinses, you will be an old hand at burping the air out.
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There is an expansion tank on the antifreeze side of the system adjacent to the 'radiator cap' coolant fill riser in the sail locker. Don't bleed it after the system is already hot and under pressure. 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. However, I did a complete flush & 3 rinse outs of the 'green stuff' from the Yanmar before changing the antifreeze type.įor 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. 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. We have the 2GM20F Yanmar in a 28.5 and changed to Yanmar's own orange antifreeze several years ago.