Yanmar 3YM20 Mixing Elbow

[davenrino]

I have a 2018 Yanmar 3YM20 with 200 hrs and it recently started revving to 2400 instead of well over 3000 going forward while still getting to 3500 in neutral. I am thinking the original exhaust mixing elbow may be restricting flow. It came with the u-shaped riser like this HDI replacement -
https://hdimarine.net/product/ymkit/






Is there any reason not to switch to the straighter replacement at half the cost? -https://hdimarine.net/.../yms-stainless-steel-mixing-elbow/

[gonesail]

i heard 600 hours as replacement schedule for the mixing elbow. but maybe yours is ahead of schedule. are you getting any steam in the exhaust?

[davenrino]

Originally Posted by gonesail

i heard 600 hours as replacement schedule for the mixing elbow. but maybe yours is ahead of schedule. are you getting any steam in the exhaust?

No steam but some black crud on the water and a small puff of black smoke when backing off the throttle.

[Tin Tin]

Why not just take it off and clean it and inspect, not hard to do. You may also have a fouled propeller or bottom. The reason for the high lift elbow is usually to get the elbow higher above the water line, depends on your situation on whether to use low rise or high rise and if you have an anti-siphon loop from heat exchanger to elbow.

[davenrino]

Originally Posted by Tin Tin

Why not just take it off and clean it and inspect, not hard to do. You may also have a fouled propeller or bottom. The reason for the high lift elbow is usually to get the elbow higher above the water line, depends on your situation on whether to use low rise or high rise and if you have an anti-siphon loop from heat exchanger to elbow.

That is the plan for tomorrow. I already went under the boat to check for fouling.