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Old 21-01-2010, 08:04   #16
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Based on an experience I had with the turbo on my car I believe the turbo might be the issue. Turbos don't have seals as such, way too hot on the exhaust side. What they have is a opening where the shaft passes through that is shaped such that when the shaft spins the inside area, where the oil is, develops a slightly lower pressure than the outside. This keeps the oil in. Your's may have been worn and was being kept 'sealed' by the oil residue. You cleaned the residue so that now the opening is a tad too large for the spinning effect to create that needed low pressure.

My experinece was having my turbo professionally cleaned and checked while I was having my engine re-built. It blew smoke for days until I finally replaced the turbo. I even had the rebuild guys put a new cartridge in it twice to no avail. The catridge is basically the entire guts. That was very weird. But I couldn't argue with the results. The rebuild guys did. After several months I got 90% of my money back.

My dad was right. If it ain't broke, don't fix it.
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Old 21-01-2010, 12:03   #17
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Turbo spools, we are only getting 8lb of boost at 2950rpm and that is the max rpm she will give. At that speed we get tons of black smoke. The prop has not been changed or touched in the past 18 months, it's a max prop. Engine does not appear to be making oil, temps and oil pressure is normal.

We pulled the after-cooler and found no blockages and the turbo blades spin as normal. At this point everyone is baffled.


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Old 21-01-2010, 12:31   #18
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I'm unclear.... is the diesel in the oil problem solved and now just a bad black smoke issue? Does it run better than before? (rough at idle)
Rebuilding injectors is a turkey shoot for sure. Many say buy new, dont rebuild. I had a Perkins 4-108 that ran good but had a slight headgasket leak. I took the head off and had it rebuilt while it was off and got talked into "rebuilding" the injectors. Once back together the boat always gave off more black smoke than previous to the injectors being rebuilt. New injectors were eventually installed ($86 each!) and the engine was perfect again.
Back to the Yanmar: I hope not for you, but my Yanmar 3 cyl had a broken lower land on one piston which didnt support the lower ring properly. It was very hard to diagnose and many $ and 3 mechanics later was diagnosed correctly... it ran rough, started hard but ran well at higher rpm.
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Old 21-01-2010, 12:40   #19
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Cylinder Glazing...

We had another discussion here about a turbocharged Yanmar blowing smoke a short while ago.

I suggested at the time that the cylinders may have become glazed, but the question (to my recollection) was never conclusively answered.

Is it possible that your engine has not been worked hard for a while and been run on synthetic oil so the cylinder bores have built up a hard "glaze"?
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Old 21-01-2010, 12:47   #20
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When you did your work for five months, was your boat floating the whole time? If so, did you have your running gear maintained? Barnicle growth on running gear can cause black smoke because the engine has to work much harder. When a diesel is under too much load it will put out black smoke. If everything was maintained properly underwater than disregard this post.
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Old 21-01-2010, 14:08   #21
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It does appear that the engine is no longer making oil, though this is hard to prove definitively because we only have about 45 minutes of total run time since the oil was changed and it got new injectors and the new lift pump.

The boat was hauled out last month and the bottom is spotless plus all the other running gear was cleaned. Its not a fouled bottom.

So.... we have new injectors (the nozzles were replaced with new), a new lift pump, new oil and filters and clean fuel, we have a turbo that spools up and spins freely, we have no blockage in the air intake or in the after cooler, the run temps and oil pressure are good. We removed the breather line while running and there is no sign of any blow-by. In addition the engine starts immediatly now, on the first turn.

She does idle better now and in general seems to run smoother since replacing the injectors.. but the black smoke remains.

We removed the valve cover and turned the engine over slowly, she definitely has compression and there are no hissing noises or anything to indicate any compression issue or valve guide issues.

Water spits from the exhaust normally and she does not run hot.


At this point the techs here want to haul the boat and try a different prop. They and the regional Yanmar rep at Mastry insist that the problem must be the prop with the Max Prop over-pitched and thus overloading the engine.

This prop has been on this boat for 10 years. I have personally seen 3400 rpm with this prop (we cannot get over 2950 at full throttle right now) and the problem with the engine making black smoke even at 2400rpm cruise so bad that it soots up the entire transom is definitely new. How can the prop be the problem when the problem is NEW? The Mastry rep says the prop has been wrong all along and overloading the engine but now things have degraded to the point where it is manifesting itself in this way.

So.... the Yanmar folks, unable to come up with any other solutions, are blaming the prop. It looks like we will be here even long and will be getting hauled out yet again and trying a different prop.

I am at a complete loss.



Terry
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Old 21-01-2010, 14:55   #22
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You could have picked up a line or something wrapped around the prop causing overloading. I would suggest diving on the prop to see if it is clear of something wrapped on it.
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Old 21-01-2010, 14:56   #23
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Back up and start fresh...

Please refresh our memories and start at the beginning...

1. The motor was working great. No smoke and could reach 3400 rpm with the existing running gear? Is this true?

2. You did your refit over a period of many months. Some items were removed from the motor, cleaned, and re-installed.

3. After the refit and cleaning of parts... Fuel was getting into the crankcase via the lift/primer pump.

4. Also, there was much smoke and loss of power.

5. New lift pump solved fuel in oil problem.

6. Injectors rebuilt but Black smoke and loss of power still a problem.

---

I would say that #3 and #5 makes sense. When you let old pumps with old rubber parts sit unused they tend to fail. Maybe they stiffen up then crack.

#6 with the black smoke and loss of power sounds like lack of air intake. Or maybe too much fuel. Seems like the only real change has been the injectors so I would suspect them. However, since you had other items removed from the motor during cleaning, I think more information from you is required:

1. What is the intake arrangement and what was done to it during the refit? Have all elbows, pipes, and filters been inspected (I know you checked the intercooler). Have you tried to run the engine with an open turbo to eliminate the intake system.

1a. Do you have any fresh air intake to the engine room/space? Did your refit close off all fresh air to the engine? Maybe it is choking because it is in an airtight space?

2. Has the exhaust been checked for any blockage or restriction, through the entire system?

3. Is it possible that, when removing and cleaning engine parts the injection pump timing, or delivery rate, or fuel pressure settings were disturbed?

4. Has Injection pump timing, delivery rate, or fuel pressure been checked?

5. If all else fails, it might be worth using brand new injectors and putting the rebuilt injectors into your spares.
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Old 21-01-2010, 16:23   #24
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What happens when you rev the motor in neutral? That would take the prop out of the equation.
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Old 21-01-2010, 16:32   #25
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We are all going to smile if we find out it was only because the engine space hatches were sealed up and the engine could not get any fresh air...
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Old 21-01-2010, 16:36   #26
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OK.... from the top as requested.

I purchased this boat, a 1981 Stevens 47, in March of 2008. It has a Yanmar 4JH2-HTE 75hp turbo/intercooled diesel engine that was installed in 1992. At the time of my purchase the engine had approximately 3500 hours. It now has about 4000 hours. It has always run great for me. It has always put out a small amount of light grey smoke at idle and under load but not anything excessive, barely noticable really. It also would put out some black smoke running at maximum rpm driving the boat at hull speed. It has never burned any oil, I do not have to add any oil between oil changes. The engine has always started very easy, on the 3d or 4th turn over when cold.

I brought the boat from St. Thomas to Jacksonville FL in June of 2009 to do extensive refit work. Since June of 2009 she has been in a slip not being run until Monday of this week with the exception of 10 minutes running to and 10 minutes from being hauled out in mid December 2009.

During November of 2009 I removed a number of ancilliaries from the engine to facilitate cleaning and painting everything. I removed the air cleaner, turbo, after-cooler, turbo oil drain tube, alternator and injection hard lines to the injectors. I stripped the engine area, treated all surfaces, primed and painted everything. The turbo was cleaned out with carb cleaner and compressed air but not at high pressure and it was not spooled up to any speed without lubrication. When reassembled, and now as verified today by hand and direct observation the turbo spins freely. Everything was reassembled and after some problems related to figuring out how to bleed the injectors so the engine would run (the Yanmar manual did not give the correct procedure) it fired right up and ran well. I did not run it under load at that point but it fired and ran normally.

When we left the slip on Monday of this week to head out cruising, the boat threw large amounts of black smoke and the exhaust water was black with soot. This was at both low rpm and under load. At cruising speed of 2400rpm the smoke and the exhaust water were very sooty black. After 3 hours of running the transom well stained with black soot.

We anchored out and I began investigating. It appeared that the oil level was higher than when we left (it was right at the full mark and after our run it was 1/2" - 1/2" above the full mark) and the oil seemed to be diluted. It did not reak of diesel, but its viscosity between your fingers did not feel like non-diluted oil. So I feel it was leaking fuel into the oil thus raising the oil level.

I called the local Yanmar dealer and make arrangments to take the boat to them Tuesday morning. I changed the oil and we motored up there early Tuesday, a run of less than 30 minutes. The engine started normally and ran fine but of course smoked like crazy.

The Yanmar dealer diagnosed a likely injector issue. They pulled the injectors and indeed they looked pretty bad. The injectors were sent out to an injector shop. They reported that 1 was all but totally plugged up, 2 others were pretty bad and only one was "decent". I had a set of new nozzles (brand new in sealed new containers) and these were used to rebuild the injectors. So we have new injectors (with new nozzles the injectors are new). At this same time based on advice received online (here) I replaced the fuel lift pump with a new unit I had onboard. I disassembled the old fuel lift pump but did not find any obvious cracks or issues with the internal diaphragm though it was clearly old.

We ran the engine with the new injectors, new oil and filter, new fuel lift pump, new fuel filters and clean fuel..... and while the engine did idle better and it general seemed to run smoother it still threw the black smoke.

We conducted a sea trial with the mechanics on board. The maximum rpm the engine will make is 2,950 measured with a seperate tach tester and matching my onboard tach, at full throttle. Thats all she will give and at that rpm under full load she basically pours black smoke and the exhaust water is sooty black.

We tested the turbo boost and at max rpm it is about 9psi. It should be around 15psi at max of 3700rpm at full throttle. The turbo is spinning but the engine appears to be overloaded and cannot reach full rpm..... or at least that is the conclusion the techs are at right now.

We removed the valve cover checked for any obvious valve issue and turned the engine over to listen for any obvious top end leaks. The engine clearly has compression as TDC can be felt as it approaches and there is no leaking apparent or other noises. Also, even when cold the engine now starts on the first turn... it basically spins and starts immediatly. Compression certainly seems good. When running we removed the breather line and there is no pulsing or any sign of any blow-by indicated at all.

We removed the after-cooler and checked for any blockage of the intake air charge. There is none, it was relatively clean. There is no blockage in the air cleaner assembly and we ran the engine with the air cleaner off with no change in the problem. With the air cleaner off the turbo can be easily spun with the finger and no obstructions or sticking is noted. Additionally when the engine is run the turbo can clearly be heard though the techs say it is not as loud as it should be because the engine is not building the rpm and boost at load as it should (overloaded).

The engine will rev to 4,000 rpm at the dock not under load (out of gear).

The techs and the Yanmar service rep at Mastry all seem to think that issues with the fuel injection pump are pretty much impossible and that any adjustments that would effect this are not possible at the injection pump.

Checking the oil after the sea trial and running for test it is not possible to tell for sure if the engine is putting any fuel in the oil. The oil level before running seemed to be just a tiny bit over full, I just checked the oil and measured the level exactly and the oil level is 7/8" over the full mark.... but the oil does not smell like diesel and it does not feel diluted (though thats not all that easy to tell).

Perhaps when I checked the oil before not all of the new oil had found its way to the crankcase? Would being overfilled perhaps cause the cranshaft to actually spin in oil and thus overload the engine preventing it from reaching max rpm? Would this be possible with no indications of oil being throw about in the breather or such?

Can a Max-Prop magically change its pitch all by itself resulting in the engine suddenly being overloaded when before it was fine? Could some piece of trash like a plastic bag be wrapped around the max prop in a fashion such that the spurs would not cut it off but it would overload the engine while also not causing any abnormal vibration nor give any other sign?

Engine run testing and sea trial were conducted with engine space doors removed on 3 sides... she is getting all the air any engine could ever want.

Are there in fact aliens living in my bilge screwing with me intent on destroying my cruising dreams and bank account?

Baffled in Jacksonville....



Terry
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Old 21-01-2010, 16:41   #27
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How much stuff have you added to your boat. I've lost 300- 400 rpm off the top end since the boat came to me race ready and empty to now with tools, anchors, dishes, food, etc.

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Old 21-01-2010, 16:51   #28
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Thank you for the detailed post. It would appear that all the proper checks have been done.

That said, I think it is a bad turbo.

Not enough air (from the low boost) for the amount of fuel being delivered will produce black smoke and soot. Having cleaner injectors would make the problem worse because now you have even more fuel than before.

Black smoke and soot are incomplete fuel burn.

Is that turbo wastegated? Could the wastegate adjustment be off (since the turbo was removed and reinstalled)? If the wastegate is not fully closed with a slight bit of pressure (from the spring) it will leak exhaust (internally) which bypasses the turbo fan (exhaust side) and reduces boost (by lowering turbo rpm to boost side).

It may be possible that the turbo had been marginal before, and disturbing it finished it off. Is there any play in the turbo shaft? If you grab the nut on the intake fan, can you move it at all side to side?
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Old 21-01-2010, 16:54   #29
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I am not a diesel mechanic, I've never turned a screw on a diesel. I'm a Porsche mechanic. I'd like to work on diesels but I haven't yet.
The names of the parts are the same and that's about it. Gas engines with a lot of gas in the crankcase, especially if it ran into the crankcase through the cylinders (via leaky injectors for instance), will wash the cylinders of lubrication and ruin the rings. Does this happen on a diesel?
On a Porsche I would do a leakdown test to see if the rings are leaking or broken or if the ring lands are broken. You can hear the air in the cylinder or cylinders that show a lot of leakdown blowing into the crankcase if it's the rings or into the intake or exhaust if it's the valves. Diesels obviously don't have spark plug holes to pressurize the cylinders but maybe the glow plug holes? Is there a similar test for diesels?
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Old 21-01-2010, 17:07   #30
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Bad rings or pistons reducing compression would have a lot of blowby in the crankcase. The owner stated this has already been looked at and there is not excessive blowby.

Diesels require compression for ignition and this motor is running well at low speed when compression would be lowest on a leaking motor and also starting quickly when compression is really needed to ignite cold fuel.

Good compression diesels start quickly.
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