Yanmar 3GM30F Elbow clean-up

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PGIJon

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Mar 3, 2012
856
Hunter 34 Punta Gorda
I began experiencing some 3GM30F overheating again at FT. I had a flow of water but possibly not enough. Having done just about everything else with the cooling system, I decided that I was going to finally replace the elbow. Some of those pictures of the mixing elbow are a bit scary! While I was unable to remove the elbow from the joint, I easily removed the exhaust elbow from the engine block with the joint and the mixing elbow attached.

The exhaust elbow was in great shape so I took it down to a diesel mechanic and after heating it to about a million degrees and nearly toppling his work bench, two mechanics we finally able to separate the pieces….

I was all ready to leave and order a new elbow when the mechanic asked me if I wanted to sandblast the parts. I figured why not. About 15 minutes later he returned with everything cleaned out, including the elbow along with a $45 bill. After I saw what a great job he did with the elbow, I decided to possibly save a few bucks and give it a try. I cleaned it up all 3 parts and painted the mixing and the exhaust elbow.

Yesterday, I reinstalled them and fired up the engine. After warming it up a bit I ran it WOT (at the dock) and them temperature never even hit 140. Maybe this weekend I’ll head out and do some WOT test in gear.

Best 45 bucks I’ve spent that day on the boat….. -Jon
 
woodster

woodster

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Sep 15, 2009
6,243
S2 9.2a Fairhope Al
thats exactly what i did on my mixing elbow and so far so good only time will tell
 
seadaddler

seadaddler

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Dec 19, 2006
5,832
Hunter 36 Punta Gorda
Just keep a good eye on where the threads are,I did what you did with heat from a shop and few years later the threads did get very rusted and last year while motoring the elbow blew
apart at the threads and the rest of the 2 parts looked real good.
Nick
 
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PGIJon

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Mar 3, 2012
856
Hunter 34 Punta Gorda
Wow... Nick, your definitely correct about the threads. They weren't in great shape but the mechanic said just to use a bunch of a Teflon sealant and keep an eye on it. There is not a lot of pressure there for it to blow out. -Jon
 
Charles Erwin

Charles Erwin

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Jan 30, 2012
1,144
Nor'Sea 27 "Kiwanda" Portland/ Anacortes
Replace the threaded coupler with new. About 32 USD. Keeping an eye on it does not work. The coupler fractures suddenly and comprehensively and there is zero chance of a temporary fix in the field.

Charles
 
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PGIJon

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Mar 3, 2012
856
Hunter 34 Punta Gorda
Hi Charles... Actually the coupler was in good shape, it was the threads on the elbow itself that were deteriorating. Makes me start to wonder if I should just replace all the parts....... -Jon
 
woodster

woodster

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Sep 15, 2009
6,243
S2 9.2a Fairhope Al
they may be close to giving up the ghost due to heat and age along with crushing when you disassembled it
 
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Charles Erwin

Charles Erwin

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Jan 30, 2012
1,144
Nor'Sea 27 "Kiwanda" Portland/ Anacortes
Male threads on the coupler are the culprit. The female threads in the other sections are way safe no matter they are not perfect. The reasons include the geometry of the threads in these thin coupler sections and the alloy of the coupler that both contribute to sudden fracture failure.

Charles
 
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seadaddler

seadaddler

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Dec 19, 2006
5,832
Hunter 36 Punta Gorda
All that heat causes the male threads to became very rusted and yes not good and yes
will cause as I found out blow apart while motoring with no warning.
But the good news when replacing the elbo they now give a new stainless double male coupling.
Nick
 
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MitchM

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Jan 20, 2005
1,031
Nauticat 321 pilothouse 32 Erie PA
beware when trying to unthread the exhaust el coupling on yan mar. yan used to make some els thread left makes TIGHT and right makes LOOSE. i found this out when my @#$ would not come off. had to call mack boring (in the days when mack boring actually talked to its non dealer customers. )
 
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PGIJon

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Mar 3, 2012
856
Hunter 34 Punta Gorda
Nick... After your experience, I think I'm going to replace the entire set.... Where did you buy your elbow that gave you a free coupler???? I use Mattos/Diversified Marine in Ft. Myers.

Mitch.... Thanks.. I actually read about the opposing threads in a different post... Good thing to bring up as someone will search and read your comment!
 
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seadaddler

seadaddler

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Dec 19, 2006
5,832
Hunter 36 Punta Gorda
Yes same place Ft Myers and stainless is not really free but is
what they now offer.
What happen was few years back I took it apart to clean out and had a local shop take apart for me and yes they used lots of heat but did not use a new stainless part.
Nick
 
Charles Erwin

Charles Erwin

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Jan 30, 2012
1,144
Nor'Sea 27 "Kiwanda" Portland/ Anacortes
There is a stainless elbow (a Yanmar clone) with stainless threaded coupler available from HDI Marine in Vancouver, Wa. It is $155 for both. Shipping is $13.

If you are interested PM me for his address.

Yanmar Elbow.jpg

Charles
 
seadaddler

seadaddler

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Dec 19, 2006
5,832
Hunter 36 Punta Gorda
I not sure pretty sure I paid same price fromYanmar bur foget how much more for the stainless maybe $25 I think.
Nick
 
bawlmer

bawlmer

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Sep 15, 2013
708
Catalina 270 Baltimore
My .02. My old mixing elbow blew a 1/4" hole through a clean painted surface from internal corrosion. A new one was relatively inexpensive and since you already did the hard work of removing it I would replace with new. You don't know what's hiding under there.
 
Ken13559

Ken13559

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Oct 29, 2005
2,362
Hunter Marine 326 303 Singapore
Sailm8, thanks for the link. I had just installed the SS U Mixing Elbow. Now they've shiny SS ones! Wish they had that sooner :(
Looks like a good deal to buy all 3 parts at one go.
 
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