Yanmar manual mixing elbow maintenance

jibes138

jibes138

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Jan 27, 2008
3,086
ODay 35 Beaufort, NC
ddrewry said:
I recently bought a Hunter 37.5 and initially thought the black stuff under the rear mattress and the engine compartment was some kind of mold... I've since discovered it is actually exhaust from the Yanmar 3HM35F... what a mess!
I'm looking to replace the whole exhaust system clear to the thru hull. There are other signs the older gentleman didn't keep up with maintenance like he should have but I've never seen anything like this. Not ready to condemn the Yanmar yet...but that's a lot of soot...
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If your exhaust is leaking you could be exposed to carbon monoxide a deadly gas. Don't use it until fixed and get a CO alarm if you don't have one
 
Jim 5757

Jim 5757

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Jun 19, 2004
365
Island Packet IP 32 99 Forked River, NJ
Not to hijack this thread, but I'm currently engaged in removing the transmission from our M28 in preparation for rebuilding same. In order to gain access, this involves removing the s/s fuel tank (Oh boy! there was a 1/2" layer of water in the bottom!), and the exhaust mixing elbow which in our case is a cast iron unit by Barr Marine.
Interesting thing is that we had no issues with engine performance other than a tendency to overheat if we ran over 3000rpm HPIM1470.JPG for extended periods. Check the pics...HPIM1472.JPG HPIM1471.JPG
BTW, this engine has approx 600 hrs with this exhaust...
 
Justin_NSA

Justin_NSA

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Jul 7, 2004
8,481
Hunter 30T Cheney, KS
rardiH36 said:
This time I did replace with a stainless steel elbow. Rather than through the eBay portal, I bought it direct from www.exhaustelbows.com. (Ben, the proprietor and craftsman/maker of the elbows was a good resource during a couple of email exchanges. He dispatched the elbow on the same day I placed my order. On opposite coasts, I had it two days later.)

I have also attached a photo of my SS steel elbow installation. It's only been about 5 months now since I purchased. So too early to determine how it will do over the long term. But this replacement has a straight run down to the exhaust hose. No bulge to allow the "puddle" raw water to remain between engine uses. The price seemed right and worth the experiment ... even though I also had seen some posts that SS might not do well for exhaust elbow duty. Looks very pretty though!
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I just bought mine from Ben as well. Great guy to work with. I haven't replaced it yet, but I plan to take side by side pics when I do this off season. One of many down time projects. I expect SS will be more resistant to corrosion, much like car makers are doing with exhaust systems on higher quality models.
 
Justin_NSA

Justin_NSA

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Jul 7, 2004
8,481
Hunter 30T Cheney, KS
Planning ahead on my elbow replacement: I have the new SS part. They do not come with an elbow to block gasket. Have those of you that have done this task been able to salvage the old gaskets or had to make new? I have not been able to find one. What material are they made from?
 
Justin_NSA

Justin_NSA

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Jul 7, 2004
8,481
Hunter 30T Cheney, KS
Thanks! I was on their site last night but I couldn't find this. Better to replace than reuse when fumes are possible.
 
kloudie1

kloudie1

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Nov 6, 2006
10,068
Hunter 34 Mandeville Louisiana
Welcome..
EDIT NOTE : Justin, that one is a four bolt gasket.. some were three bolt .. I believe the three bolt ones were earlier than yours..
 
Justin_NSA

Justin_NSA

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Jul 7, 2004
8,481
Hunter 30T Cheney, KS
Thanks again. Niemiec is who I've ordered from in the past. Their relationship ito TOAD isn't all that clear to me.
Mine supposedly is a "3 bolt" because "they only use 3 of the 4" according to what I've read on this. I need to take a close look before I order the wrong part
 
I

IH82BL8

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Feb 6, 2013
437
Hunter 31 Deale, MD
This seems like a good time to ask; How difficult is it to remove one of these that has been in placed for who-knows-how-long? I was thinking this would be a good time to start the penetrating oil ritual.

Thanks.
 
Justin_NSA

Justin_NSA

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Jul 7, 2004
8,481
Hunter 30T Cheney, KS
IH82BL8 said:
This seems like a good time to ask; How difficult is it to remove one of these that has been in placed for who-knows-how-long? I was thinking this would be a good time to start the penetrating oil ritual.

Thanks.
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That's my plan as well !
 
seadaddler

seadaddler

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Dec 19, 2006
5,821
Hunter 36 Punta Gorda
Depends but need to be careful when taking the bolts off the mixing elbo and just go
easy until the 3 or 4 bolts and take the hose off first and usually not easy.
If 2 part mixing elbo than go to a shop to take apart and replace,don't try taking apart yourself especially if been on a long time and maybe be ready to replace the whole thing here with one of those saintless ones.
Nick
 
Warren Milberg

Warren Milberg

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Dec 1, 1999
2,391
Hunter 28.5 Chesapeake Bay
Last year I helped a friend replace the 2-part elbow on his 25-yr old 2GM20F. Hardest parts were laying on top of the engine to gain access to the bolts -- which came off relatively easily. It was harder to replace them when we bolted on the new elbow as you had to keep the new gasket in place while holding the new elbow and trying to start the bolts by hand as you could not see them on this engine. You needed 3 hands or a trained monkey. Another difficulty we had was replacing the reinforced exhaust hose from the elbow to the muffler which is probably worth doing if the elbow and hose were old OEM parts.
 
heritage

heritage

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Apr 22, 2011
930
Hunter 27 Pecan Grove, Oriental, NC
I did a 3gm30f mixer replacement a couple of years ago. The bolts into the manifold were no problem. I did have good access to the stern of the engine though. Good idea to remove the exhaust hose before loosening the unit from the engine. This doesn't apply to you, Justin, but for someone installing an OEM riser and wanting to reuse the manifold extension, it is almost impossible to separate the riser from the manifold extension without breaking the coupler. You will need a really large and well set vise and a wrench with long cheater bar to break (literally) things apart. Hopefully you can salvage the manifold extension but more than likely will need a new threaded coupler.
 
Justin_NSA

Justin_NSA

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Jul 7, 2004
8,481
Hunter 30T Cheney, KS
heritage said:
I did a 3gm30f mixer replacement a couple of years ago. The bolts into the manifold were no problem. I did have good access to the stern of the engine though. Good idea to remove the exhaust hose before loosening the unit from the engine. This doesn't apply to you, Justin, but for someone installing an OEM riser and wanting to reuse the manifold extension, it is almost impossible to separate the riser from the manifold extension without breaking the coupler. You will need a really large and well set vise and a wrench with long cheater bar to break (literally) things apart. Hopefully you can salvage the manifold extension but more than likely will need a new threaded coupler.
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Actually this does apply to me. I discovered that I have the 'optional' U-type elbow that looks like what you are describing. Can I change over to the stainless one I bought or do I need to return it? Why is this U-type optional according to the Yanmar service manual? What is gained by the large 'U'? It it the better design and why/why not? I'm new at these diesels.
 
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