Adrianp 124 Posted September 5, 2021 Share Posted September 5, 2021 We have 2 x Yanmar 3YM30 in our cat and I'm due to replace the stupid yanmar exhaust mixing elbows that seem to last only a few years. I'm looking at the HDI ones rather than the Yanmar one as I hear good things about them. We currently have the high-rise mixer style but I don't think we need them anymore as we have changed the rest of the exhaust system. Original Exhaust system : High Riser Mixer (no anti syphon fitted. Mixer head is about 150mm above waterline) Wetbox in bilge Exhaust hose then looped up about 300mm above waterline Hose ran down to outlet about 100mm above waterline Marked as pink on pic below I was nervous out how low the loop was, so I changed the system to (new loop in green on pic below): High Riser Mixer (no anti syphon fitted. Mixer head is about 150mm above waterline) Wetbox in bilge Exhaust house then loops up about 1000mm above waterline via another muffler (only really used at a 180 degree bend). Marked as green on pics below. Exit via the existing outlet 100mm above the waterline I think I no longer need the high rise mixer style as the high looped exhaust stops the risk of anywater coming back up the outlet. I will need a anti syphon device to stop water coming via the water feed. The normal elbow mixers are half the price and half the parts to corrode, so It would be nice to change it I can. What do you think? Quote Link to post Share on other sites
Adrianp 124 Posted September 5, 2021 Author Share Posted September 5, 2021 Wanting to use these: Rather than these: Quote Link to post Share on other sites
Kick Ass 49 Posted September 6, 2021 Share Posted September 6, 2021 3gm30 just has the mixing elbow to wet box then loops and out exhaust. Boat is 1994 and is all original and never had an issue. Quote Link to post Share on other sites
Kick Ass 49 Posted September 6, 2021 Share Posted September 6, 2021 Also still on the original elbow 27 years old and going strong. Quote Link to post Share on other sites
waikiore 454 Posted September 6, 2021 Share Posted September 6, 2021 Much as I dont like the inefficient shape (gas flow wise) of the high rise, I would be hesitant in going to the older lower style -I run a 3YM30AE as well. What you have done aft is a good move, but the crucial points to observe are maximum drop to the waterlock from the injection elbow-and volume of the waterlock -it has to take every drop from the high point of your new loops and dripping from the elbow once shut down, without any heading back up towards the engine. These points are of course common to all yacht engines, and yes before someone asks typically the exhaust hose is 1/3 water on shutdown. Quote Link to post Share on other sites
whitepointer 34 Posted September 6, 2021 Share Posted September 6, 2021 You can keep the original first section of exhaust, just replace the elbow and nipple, as it is the only part that has saltwater passing through it Quote Link to post Share on other sites
Mr Hell 0 Posted February 18 Share Posted February 18 On 6/09/2021 at 11:23 AM, Adrianp said: Wanting to use these: Rather than these: Hi Adrian, I know you raised this a while ago but I was just wondering which type of exhaust elbow you went with and how has it performed over the last couple of years? Thanks. Quote Link to post Share on other sites
Adrianp 124 Posted February 18 Author Share Posted February 18 I got the HDI Marine ones but only the elbows. They seem good but haven't actually pulled one apart yet so who really knows! We also make sure we run the engines a bit harder than we used too to stop any soot build up. Quote Link to post Share on other sites
whitepointer 34 Posted February 19 Share Posted February 19 I've had a HDI 3YM elbow for a few years, no issues, motor mostly running in the 2500 to 3000 rpm range, Quote Link to post Share on other sites
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