2000 Yanmar 3GM30F Black Smoke and no power

[jviss]

I didn't see any sign of gasket sealant when I took it off. Is there suppose to be?

There typically isn't for original equipment, it it's a metallic exhaust flange gasket; but there are those who differ, and the debate is a stepchild of the engine oil debate. I've done this on a Universal M25 and used the new metallic gasket bare. Get a new gasket, at least.

 

[sailcapt340]

When this first happened I shut the engine down.
Then started to check the areas you are mentioning. The air filter (2 years old) is going to be replaced along with the elbow now. It is intact so I ruled that out.
Fuel and filters (replace last year) were clear and showed no debris on the filters. As part of my rounding maintenance they get replaced every two years anyway. Cheap insurance.
I removed the impellor to inspect that (new in April). I replace that yearly anyways. It was fine. The alternator spins freely and no telltale noises coming from that either. The engine ran as usual, just up to 1200 rpm as I mentioned so....
I really want it to be the Elbow, given its age in service, but I am prepared, as best anyone can be for the alternatives.
I'm saving the injectors and their testing, as a last resort. If I have to get involved in them I will, but hoping for the elbow and the very obivious signs I see from just the initial inspection I've done.
Today I just contacted Yanmar and Mack Boring (here locally) for the correct part numbers. I've gotten numerous part numbers all weekend long from the internet and burned myself out looking. These parts numbers change like the weather.
I've got a current list and working with a local Yanmar Dealer to get them as soon as possible.
Other than that, it's where I am currently. And hoping for the best as I go along.

 

[jviss]

Yes you are seeing the entire unit, manifold, nipple and elbow

What you have removed here is not the manifold. The manifold is the thing that collects all three exhaust ports on the head into one outlet - hence "mani"-fold. The thing you have removed is a flange, riser, and mixing elbow. The flange attaches to the manifold. The riser is not standard Yanmar, as it's supplied by the engine installer, usually.

When I re-did such an assembly I purchased a new flange, just in case I ruined the old one taking it off the pipe; a new flange gasket; new studs and nuts. I had a riser made by a local plumbing place out of schedule 80 iron, and fitted the new elbow and flange. I then wrapped it in exhaust insulation.

 

[jviss]

If you are able, try to get the OEM name and part number off the injector. They are undoubtedly not made my Yanmar, probably Denso or Zennoh. Buying them from an agricultural equipment supply place is much, much less expensive than a Yanmar or Westerbeke or Universal part. I bought new injectors for a Universal M25 cheaper than the cost of rebuilding the old: $85 each for new. Universal part was $365 each. (Not sure what Yanmar part costs.)

 

[Panera]

I had a similar problem with my Yanmar, increasing speed generated black smoke and loss of power. Turns out that one of the fuel bleed valves was loose, tightened the valve and all is well.

Worth a try!!

 

[Charles Erwin]

Jviss. Yanmar makes two factory elbows. The photo is the Yanmar cast iron riser. The other model is not cast and there is no rise to the shape. Rare to see shop made on these motors. The best direct bolt on part is HDI Marine - no contest. Flange riser nipple all in stainless. Gasket too. All for about $275 US. Elbow only $155. https://hdimarine.net/product-category/yanmar/

Charles

ps. The injectors are Yanmar specific. They are the same for all three GM models.

 

[jviss]

The photo is the Yanmar cast iron riser.

I was unable to locate that in the Yanmar parts book. Maybe the book wasn't up to date, or comprehensive?

ps. The injectors are Yanmar specific and the are the same for all three GM models.

Yanmar makes their own injectors? I am surprised by that.

 

[SouthernYankee]

Your symptoms sound like a faltering cylinder (i.e. loss of compression). One of your injectors may be still pumping fuel into the cylinder but it is not igniting because of low compression, the fuel is just burning as it hits the exhaust (i.e. black smoke). Certainly would explain loss of power. You can easily test this by running the engine (even at idle speeds) and cracking the fuel line going to each injector (loosening the nut holding the fuel line on the side of the injector, not return line on top which connects each injector together via banjo fittings).
In a properly running engine, cracking the line will cause the pressure to drop just enough so that the injector doesn't open, i.e. no fuel to the cylinder, and you'll hear the engine run rough. When you re-tighten the fuel line you should hear the engine run more smoothly again. If the engine doesn't falter for that particular cylinder you may have found your problem area. If that is the case you may have poorly adjusted valve, or piston rings have started to fail, or... Just a thought.

 

[sailcapt340]

Charles,
The site, HDI Marine you brought up piqued my interest. I went on there site and found the model they have for my engine. I contacted them and waiting to hear back.
If you have used theirs, maybe you know.
The pictures of their model show a smaller round opening in the riser as compared to my original, which has a larger rectangular opening. Did this reduce the flow of water in your engine to any noticeable effects?
Thanks for any input.

 

[jviss]

If I read you correctly, that rectangular opening in your pic has no water flowing through it, only exhaust gas. The water is introduced at the elbow, and flows out the other way into the hose.

 

[sailcapt340]

Your right, I wrote it backwards. I meant the gases. But did the model design effect performance of the engine overall?

 

[Charles Erwin]

Charles,
The site, HDI Marine you brought up piqued my interest. I went on there site and found the model they have for my engine. I contacted them and waiting to hear back.
If you have used theirs, maybe you know.
The pictures of their model show a smaller round opening in the riser as compared to my original, which has a larger rectangular opening. Did this reduce the flow of water in your engine to any noticeable effects?
Thanks for any input.

Round or square it is the area that matters. After all the rubber exhaust hose is round. And the inlet/ outlet to the water lock. In any case never could detect any performance degrading. Also never heard anyone complain either. You could ask when they call back. Remember your present system has been pretty strangled probably for a good long time so performance will improve anyhow.

ps You could always use your old flange- the square one

 

[splax]

I disassembled the elbow off my 3gm30f by putting the manifold in a vise and using a pipe wrench to remove the elbow from the coupling threaded into the manifold. the elbow has the lefty threads

 

[Claude L.-Auger]

Hope this is not too late. 2 years ago I ordered the stainless steel u-elbow with the left-hand/right hand nipple from the folks in Vancouver, Washington. Don't remember if it was HDI or someone else but I have been very happy so far with more than 200 hours on the engine since. Cost was $175 + $15 for shipping and they threw in the gasket !
Hope that solves your problem.

 

[sailcapt340]

Charles,
Your right about the system being strangled for a long time. As I have lots of time on my hands now and thinking back I do remember seeing "some" black smoke prior to this date, just a puff here and there, really never gave it to much thought. And if I did notice a loss of power I attributed it wind and tide action. Pretty dumb on my part. Won't happen again though.

Claude,
I have calls and emails out to HDI now but have yet to hear from them for the past three days. Their web site shows the part is "out of stock". I have new parts (all components) coming by tomorrow from Yanmar and plan to remove and install right away.

Thank you for the good wishes.

 

[sailcapt340]

Just got back from picking up my new parts. I'll be re-installing tomorrow. Dry fitted the parts together and the only thing I see is the water intake (installed at the factory) is at a slight downward angle as compared to the original.
I'll probably need a longer hose coming from the vented loop so I don't get a kink in the line. But I'll know better once at the boat.
From looking into the new elbow, there really isn't a lot of space inside in the 2 chambers and I can now see how and why they will foul over the years.
I plan to use some anti-seize on the threads to help in removal down the road.
I'll post some pictures as I go along.

 

[jviss]

I plan to use some anti-seize on the threads to help in removal down the road.

Good idea.

 

[sailcapt340]

Well, problem solved, the job is completed and it's running perfect again! No Black Smoke or loss of power. Hard to say if I have more power but I'm sure there is some.
Due to the confined space and impossible to even get the size wrench I needed to connect the parts in there, I assembled all three pieces outside and then lifted it into place. Not an easy thing to do, what with holding the part and trying to start a bolt. By far that was the hardest part.

I reused the existing exhaust hose, for now. As no one had the size I needed when I needed it. Everyone can get it in two days but that's no real help. Heading out to Newport later today for lunch and will get it there and install tonight. No real issues getting the old one off, used a good pair of rubber palmed gloves and a filter wrench for grip and it twisted off easy enough.

I did have to use a longer hose from the vented loop to allow for the angle of the fitting on the elbow. I simply routed it behind the engine instead of across the top as it was.

Took some photos of the process for others to see and judge the work involved. In the picture of the old parts you can see a large chunk of carbon (actually there were 2, same size) that fell out when I removed the elbow. It was just a blocked mess.

Thank you everyone for the support and advice. Hope I can return it someday only under much better circumstances for all of you.

 

[kappykaplan]

Happy to see that you’ve gotten it fixed.

 

[justsomeguy]

Ain't it great when a successful follow-up gets posted?