Went sailing this weekend and while I was raising the sails and letting the engine idle, smoke started coming out of the engine bay. I finally found the problem being a broken piece on the exhaust system or siphon break?. Unfortunately, our trusted diesel mechanics can't get to it until mid September. Having worked on numerous engines, I'd like to try and fit this myself, but unsure of exactly which exhaust manifold or other pieces that I should buy. I've looked in the Yanmar engine manual but only see the mixing elbow. ANYONE have part numbers for this repair?
Hunter 34 1984 Yanmar 3GMF issue
- Thread starter Mike Oldak
- Start date
I had the same thing happen to me a few years ago. I replaced the manifold, coupler (the part you broke) and the mixing elbow with this > Stainless Steel Exhaust Elbow Kit Fits for Yanmar 1GM 2GM Engines 128370-13600 – LUFT-MEISTER
Here is a similar setup on eBay for less. Stainless Steel Exhaust Elbow 128370-13610 for Yanmar GM/HM 104214-13531 | eBay
Here is a similar setup on eBay for less. Stainless Steel Exhaust Elbow 128370-13610 for Yanmar GM/HM 104214-13531 | eBay
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That has nothing to do with your siphon break but don't let that worry you.
You definitely don't want to buy the exhaust manifold as that's part of the engine block.
As @BrianQ has suggested, the easiest approach at this point is a complete new exhaust mixing elbow assembly. With the nipple broken, its removal will be next to impossible and the mixing elbow itself will likely be in need of replacement due to carbon build up.
Do you have an actual shop manual (not a maintenance manual) for the 3GMF ? Are you sure your engine is a 3GMF and not a 3GM30XX ? The last manual printed for the Yanmar GM series was in 2002 and does show the complete exhaust assembly.
The newer 3GM30XX (overbored) will have the same exhaust assembly as the older 3GMXX series.
Not familiar with the two SS assemblies listed above by @BrianQ but the most common SS units are sold by HDI Marine and they know SS exhausts inside out and backwards. A human voice will answer all your technical questions :
Stainless Steel Exhaust - HDI Marine
Explore our engineered stainless steel exhaust components for boats. Ensure durability and quality. Shop now!
hdimarine.net
Locate a proper shop manual which may be available in the SBO site archives here. Also, see if you can locate the aluminum ID plate on your engine to ensure yours is a 3GMF and not a 3GM30F.
The literature I have says they're the same mixing elbow assembly but don't take any chances when talking to HDI.
Just enough background to get you into serious trouble when dealing with the exhaust. You "were" going to have this work done by a mechanic and not do it yourself ? ? ? None of us were born with this knowledge so do your research. If you can't get a proper shop manual, search the archives here for Yanmar mixing elbows or perhaps HDI can supply instructions. This one has some surprises that you'll never notice until it's screwed you around a few times (literally).
This is mine after inspection and before replacement.
Read and follow all the instructions and you should have no problems with the replacement.
Very Key Point…Are you positive of your model number.
I replaced my mixing elbow a few years back, not because it broke as yours did, but it was clogged.
Spray, wait and spray again…those 4 bolts with a good penetrating spray. You don’t want to break one off in the process of removing them. That’s a whole other job.
And spray the exhaust hose as well, to release its seal on the elbow or you may be replacing that too.
I’ve added a few photos of my replacement for you to look at. Both before and after so you can see what you may find.
In one of my photos you will see an oil filter wrench on the exhaust hose, it gave me the torque I needed to break the seal. And you’ll see the hidden rust on the bolts also (Spray and re-Spray)
Even though mine is a 3GM30F the process is basically the same. Be patient and it will go smoothly.
It looks as if you have room to work in a fairly open space.
Time and patience is the key.
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Hey, Mike.. I think Ralph is right on with the recommendation on HDI. I see one of their dealers in Annapolis..
You (maybe) could save a couple of bucks by re-using the exhaust elbow (attached to the engine manifold) but the Mixing elbow and joint and gasket are probably necessary. The elbow at the engine can only be saved if the lower part of the joint can be removed without cracking the elbow, probably a 60% success thing IF the shop knows what they are doing. It will involve a good bit of heat and some chiseling.. Otherwise, the whole kit is the way to go. Use anti-seize on the joint threads and the bolts holding the elbow to the engine.
The 3GMF is the original engine for the boat and unless its been re-powered, that's probably it ..
Let us know how it goes.
You (maybe) could save a couple of bucks by re-using the exhaust elbow (attached to the engine manifold) but the Mixing elbow and joint and gasket are probably necessary. The elbow at the engine can only be saved if the lower part of the joint can be removed without cracking the elbow, probably a 60% success thing IF the shop knows what they are doing. It will involve a good bit of heat and some chiseling.. Otherwise, the whole kit is the way to go. Use anti-seize on the joint threads and the bolts holding the elbow to the engine.
The 3GMF is the original engine for the boat and unless its been re-powered, that's probably it ..
Let us know how it goes.
Clogged ?
Now THIS is what you call a clogged elbow :
I figured something might be wrong because I couldn't see a flashlight from one end to the other. From previous experience I knew that the carbon deposits had the consistency of tungsten carbide so it wasn't a likely prospect for rehabilitation. Hence I sectioned it out of boredom.
I was amazed that the engine suppplied power with the exhaust somehow finding its way out through a 1/4" hole.
And that's what we called the good old days.
Now, I've gone with an HDI SS mixing elbow which completely lacks any excitement factor whatsoever. This is a shot from last year looking into the outlet of the 8 year old SS mixing elbow :
Mind you, at the cost of what a Yanmar cast iron elbow must be worth today, I would have had to get a second job to pay for a new CI elbow every 7-8 years.
This is the purchase cost of a cast iron elbow back in 2012 :
I don't know if I could afford a CI one today.
I don't even think the HDI SS mixing elbow only is that expensive today and it's good for what,
maybe .................. a bloody long time.
THANKS EVERYONE!! I've rebuilt a number of gas engines on 60s era British sports cars probably have tackled many 50 year old rusted bolts. Since my trusted shop can't get to it until late September, I will probably try to do the job myself when I return in early September. It looks like the treaded pipe between the elbow and mixing elbow sheared off, so I'm assuming that the pipe is heavily rusted into the elbow and thus will try to replace all the pieces. Found the service manual on the site and aside from rust, the job looks doable.
Thanks everyone for the great assist and location of service manual and replacement parts on Amazon.
Thanks everyone for the great assist and location of service manual and replacement parts on Amazon.
Jeez do I remember that from the first time I was doing an inspection since receiving the boat new in 1999. You're a lot more ambitious than I was. I quit after a short time and hacked the hose off with a hack saw right under the outlet of the mixing elbow. It was only about three feet to the water muffler. Completed the deed back in the workshop.
I learned my lesson after that and coated the inside 2 inches of the exhaust hose with lots of parting compound. Wasn't too sure if I had good holding power with all that parting compound in there. Held the elbow in a vise and installed the new 3 ft. piece of hose with one only hose clamp and went at it with an oil filter wrench. Couldn't budge the hose with only one hose clamp in place. Good enough for government work.
Speaking of parting compound, I also learned to slather it on the bolts on the elbow and the graphite gasket on the elbow flange to make life much easier. The graphite gasket needs to be shaved off with an exacto knife to get the flange faces clean if parting compound isn't used. And "no" I don't have shares in the company that makes the stuff.
I would not have believed it without seeing with my own eyes; mixing elbows on Amazon Prime with free two day shipping! Crazy!!
Yes, surprising.
But would you want cheap Chinese knock-offs on your boat ? Cooking utensils great. Music and entertainment great. Engine components ........... your boat, your choice®. With special thanks to Stu Jackson
Yep, That’s what I had, a clog. Just didn’t put it in with the other pictures. Amazingly identical…..
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Excuse me, but this entire thread has been about mixing elbows, and nothing else. I fail to see the point of your comment.
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Great Thundering Mother Murphy ! ! !
What are you motoring around in ...... a mixture of sulphuric and nitric acid with a touch of nuclear waste thrown in ? I can't believe the amount iron corrosion products in your water passage. And don't tell me that you engine actually ran with less that 1/8" dia. hole in the exhaust gas passage ! ! ! ! Mind you, I guess it's possible when I had 1/4" dia' hole and didn't really notice much of a power loss.
Any idea how many operating hours (or just years) your engine had on it when you sectioned the elbow ? The crazy thing is that I have ALWAYS had the same problem with blockage and yet my exhaust is always invisible. And that's even when the engine is running
. Always has been from day one when the engine was brand new with zero hours and yet I was in for a new elbow every 5-7 years. And no idling. Go fast or go home. Many people on this site have said they go for decades with no problems and running under the same conditions as myself. There's just no justice in this world.Now, I just don't give a damn. I now have a SS elbow and so far nothing sticks to it ............................ yet. Have you had a chnce to inspect your interior yet ?
We bought our 2000 340 new in January 2000.
According to my log….I replaced the original elbow you see in the photos….July 2018 - Replaced Yanmar Mixing Elbow and Riser (@ 387 hrs). So I went 18 years….then
How I noticed it needed replacing was by a shiny sheen of black soot on the water trailing behind me when we untied from the mooring one day. I could barely get the boat to move, just no power whatsoever. My guess was we went about 100 feet, turned and barely coasted back to the mooring. But up to that day I never felt or noticed any loss of power or speed.
We now have 439 hours on the engine.
And yes I did check it once since then about 2 years ago. And it was clean.
As for the “justice in this world” I can’t explain that either. But stainless is the only way to go.
Now there IS a lack of justice. I tried just as hard and still got hosed every 5 - 7 years.
C'est la vie.
This is a one of those real puzzles as to the why’s that make this happen.
I scrolled throughout the forums and found my original posting regarding my loss of power and all the kind help and guidance I received from others here.
It was from July 2018 titled “ 2000 Yanmar 3GM30F Black smoke no power”. It will help others facing this situation.
Interestingly enough, the only “single time“ I ever heard anyone mention a mixing elbow anywhere, ever, was in 2000 when the man behind my mooring mentioned he had to replace his. I saw a huge monkey wrench in his hand and said to myself I don’t want any part of that thing.
I don’t know why he needed something that big or even how he swung it around in an engine compartment. And really don’t want to know.
I guess it just happens.
I scrolled throughout the forums and found my original posting regarding my loss of power and all the kind help and guidance I received from others here.
It was from July 2018 titled “ 2000 Yanmar 3GM30F Black smoke no power”. It will help others facing this situation.
Interestingly enough, the only “single time“ I ever heard anyone mention a mixing elbow anywhere, ever, was in 2000 when the man behind my mooring mentioned he had to replace his. I saw a huge monkey wrench in his hand and said to myself I don’t want any part of that thing.
I don’t know why he needed something that big or even how he swung it around in an engine compartment. And really don’t want to know.
I guess it just happens.
Great information already posted. Ours failed the same way in 2011. We were the cruise leaders for a revived weeklong yacht club bluewater cruise from Alameda to Monterey, California. We hadn't gone a mile before that interconnecting piece snapped and filled the engine compartment with smoke. We sent the rest of the participants ahead and we side tied the dinghy to the boat and went back to our slip with the outboard. Since it was the Saturday before the 4th of July, the Yanmar store was closed until Tuesday. I found the part that bolts to the engine had a 1-1/4" right handed pipe thread. By carefully using a hack saw blade and chisel I was able to collapse the remaining piece and extract it. At least @Mike Oldak yours broke off above the hex portion of the joint. Mine was flush below that portion. Off to the hardware store for plumbing parts. Stu, do you remember Pagano's? I fabricated this beauty here as a temporary fix. We weren't going to miss out on our cruise that hadn't happened for 12 years. This shot most of the day but by 6:00pm we were off again. We went under the Golden Gate Bridge at 8:30 pm and turned left pulling in to anchor at Half Moon Bay at 12:30am. While enroute, 6 miles offshore we were treated to two fireworks shows; one in San Francisco's Golden Gate Park and the other in Pacifica. Everyone else was already tucked in for the night at Half Moon Bay. We arrived in stealth mode. They were sure surprised when they all woke up the next morning. "Where did you come from?" As soon as we returned I bought the proper mixing elbow and kept my little beauty as a spare. There weren't any stainless ones available at the time.
The only other tip I can offer is instead of using the four 8mm (I think) bolts to attach the exhaust back to the manifold is to substitute two studs. That gives you something to hang the gasket and elbow on first as it can be challenging to hold all those items steady and start the bolts especially behind the engine when you can't see anything. Use nuts and split washers on the studs. And later I got rid of that little bronze elbow and swapped it for a straght one as it would always clog with salt crystals at the worst time.
The only other tip I can offer is instead of using the four 8mm (I think) bolts to attach the exhaust back to the manifold is to substitute two studs. That gives you something to hang the gasket and elbow on first as it can be challenging to hold all those items steady and start the bolts especially behind the engine when you can't see anything. Use nuts and split washers on the studs. And later I got rid of that little bronze elbow and swapped it for a straght one as it would always clog with salt crystals at the worst time.
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I sure do! It was the first hardware store I called My Favorite Marine Store!
You essentially made an exhaust elbow into an exhaust riser. Much improved flow characteristics.
I have studs, but use a small amount of gasket sealer on the flange side only - never on the engine side - to keep it in place.