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Yanmar mixing elbow question

Oct 24, 2010
2,399
Hunter 30 Everett, WA
Our Yanmar 2GM20F had a clogged mixing elbow within a year of when we got her. Now 5 years later I removed it to inspect and try to clean it out. It's hardly coked up at all. So my question: how long should I go before inspecting it? I know these are common Yanmar issues.

Ken
 
Oct 29, 2005
2,185
Hunter Marine 326 303 Singapore
Before switching to SS mixing elbow, I would do annual cleaning and decoking/derusting. With SS mixing elbow, I still remove it annually but found nothing much to clean for last 3 years. However noted some chloride stress corrosion which was easily patched with Devcon Plastic Steel after clean up.

Ken Y
 
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RoyS

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Jun 3, 2012
1,207
Hunter 33 Steamboat Wharf, Hull, MA
Have Yanmar 2QM 15 with a Yanmar mixing casting operating in salt water. Have not experienced clogging with coke but have experienced corrosion and rust through. I removed and inspected last elbow at four years (about 400 hours) and found neither excessive corrosion nor coke build up. Currently expecting six year life for the Yanmar mixing casting.
 

DougM

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Jul 24, 2005
2,180
Beneteau 323 Manistee, MI
I have seen a lot of posts about coked up mixing elbows on Yanmar diesels and from what I can discern they all refer to boats sailed in salt water. So the question is does the coking problem only occur on boats kept in salt water?
I have heard very little conversation where I sail about issues with mixing elbows either coking up or corroding and I wonder I if its just not been at a place or time where it has been discussed. I also wonder if the issue is unique to Yanmar diesels.
 
Oct 24, 2010
2,399
Hunter 30 Everett, WA
I have seen a lot of posts about coked up mixing elbows on Yanmar diesels and from what I can discern they all refer to boats sailed in salt water. So the question is does the coking problem only occur on boats kept in salt water?
I have heard very little conversation where I sail about issues with mixing elbows either coking up or corroding and I wonder I if its just not been at a place or time where it has been discussed. I also wonder if the issue is unique to Yanmar diesels.
We are always in saltwater or brackish water. When we got the boat there was no hour meter (I added one). When I tore it apart after a year or so, the opening in the coke was smaller than a pencil. Now 5 years (about 370 hours later) pretty clean. I managed to scrape out a tablespoon or two of loose particles. I'm thinking when we bought her the elbow may have never been removed (The boat's from 1989).

Ken
 
Dec 1, 1999
2,391
Hunter 28.5 Chesapeake Bay
Your engine will tell you when it’s time to inspect and/or replace the mixing elbow. If your engine can pull 3400 rpms smoothly and without smoke the elbow is probably ok.
 
Nov 22, 2011
980
Ericson 26-2 San Pedro, CA
Your engine will tell you when it’s time to inspect and/or replace the mixing elbow. If your engine can pull 3400 rpms smoothly and without smoke the elbow is probably ok.
If that mixing elbow has a design similar to the one on my 1GM, one way it will tell me that I *should have* inspected it is when it introduces water into the cylinder and potentially ruins the engine! Removal and inspection of the mixing elbow should be a scheduled maintenance item, not one that is ignored until it fails. The manual recommends periodic inspection for a reason.
 
Jul 27, 2011
4,530
Bavaria 38E Alamitos Bay
I’ve inspected me SS elbow, 3jh3E, twice in 16 yr of ownership, 2400 engine hr; most recently last summer. No clogging.
 
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