Yanmar 2GM20F mixing elbow replacement

[Compass790]

Originally Posted by djousset

I replaced the mixing elbow on my 2GM20F this past season and had the same question. I was advised by many, including the shop guys at the yard to go with the cast iron. Consensus seemed to be that this was not the environment for SS, perhaps because of the welds.

FYI There is no welding on the HDI marine cast ss elbows as, AFAIK, all cast & threaded.

[Frankly]

[QUOTE=Compass790;3569462]Can you tell us which brand ss elbow you used/ or post a picture?. QUOTE]


The version I installed was the 316SS cast model. It has looked just like new until last year when I noticed a small rusty spot on the side (water jacket). It has been dripping down onto the top lip of the exhaust manifold adaptor. I am curious to look inside to see if this leak was just a fluke or the beginning of larger scale corrosion issues. I turn an Autoprop which appears to load the engine more than fixed prop. Carbon build up has been an issue with past elbows.

Many years back with my first OMC IO a mechanic told me to replace the elbows every 4 or 5 years as normal maintenance. "Don't look, just throw them in the trash". Pretty much followed his advice for 50 years. Thought this SS version might change the rule. Will see.


Frankly

[Island Time O25]

Best deal on SS Yanmar mixing elbows. Bought from them about 5 years ago.

https://exhaustelbow.com/

[Compass790]

[QUOTE=Frankly;3569511]

Originally Posted by Compass790

Can you tell us which brand ss elbow you used/ or post a picture?. QUOTE]


The version I installed was the 316SS cast model. It has looked just like new until last year when I noticed a small rusty spot on the side (water jacket). It has been dripping down onto the top lip of the exhaust manifold adaptor. I am curious to look inside to see if this leak was just a fluke or the beginning of larger scale corrosion issues. I turn an Autoprop which appears to load the engine more than fixed prop. Carbon build up has been an issue with past elbows.

Many years back with my first OMC IO a mechanic told me to replace the elbows every 4 or 5 years as normal maintenance. "Don't look, just throw them in the trash". Pretty much followed his advice for 50 years. Thought this SS version might change the rule. Will see.


Frankly

The Yanmar cast iron elbows are meant to be replaced every 4 years IIRC & they say in our manual inspect every 300hrs. I doubt many owners do that.
Have had + 15 year life with made up sched 10 pipe 316L mixing elbows but not the jacketed design as stated in earlier post. You can see why they have clogging problems if you look at this cutaway.
Sorry cant seem to load pic of cutaway.
My version is proving much better at not clogging so far but I havent done enough hours yet. It should be better as bore is bigger & ss has poor thermal conductivity so carbon wont stick so easy is my GUESS
Your leaking ss elbow MAY be a casting fault but yea be interesting to have a look inside

[Frankly]

After 7 years and 1,000 hours Pulled the old SS one and the passages were clear (exhaust and water). Based on the small pinhole leak and over 50 years of messing with marine exhaust systems decided to replace the elbow, nipple, and manifold extension in SS from HDMI Marine.

Frankly