Yanmar Smoking and Making Oil

[Chief Engineer]

Before you start up, check and make sure the engine stop is not partially engaged.

Also, check that your throttle linkage has full travel

When you do your sea trial, bring it up slowly.

I am taking a "shot in the dark" and estimate your Length Water Line is around 45 feet.

That will give you a theoretical hull speed of almost 9 knots

Keep in touch

[Laidback]

STEVENS 47

Builder/Designer
Builder: Stevens Designer: Sparkman & Stephens

Dimensions
LOA: 47' LWL: 37'9" Beam: 14'3"
Displacement: 32,000 lb. Draft: 6' Min

Engines
Engine(s): Yanmar Engine(s) HP: 75 Engine Model: 4JH2-TE Turbo
Cruising Speed: 7.5 knots; Max theoretical 8.23 knots

Tankage
Fuel: 94 Water: 250 Holding: 40
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If you can cruise at 7knots at a reasonable RPM without black smoke - that should be target benchmark.

[Tspringer]

The problem is not Turbo. I got the new turbo installed, buttoned everything up, got her up to temp and went out for a sea trial. Problem is exactly as before. Max rpm at full throttle is 2,950 at which point the boat pours black smoke.

While installing the new turbo I double checked the exhaust and intake systems to make sure no rags or such had been left behind before or any other obvious air blockage.

So.... back to square zero. I guess we are down to 3 options at this point as far as I can tell: replace the injection pump, haul out and re-pitch the prop, go for a full rebuild or repower replacing the engine.

At this point we are all just frazzled and disgusted. The kids want to go home. So do I. I guess we will get hauled out again and try to drop the pitch on the max-prop by 4 degrees.... this is what the max prop guys said try though they did not really believe the prop pitch could be the issue if it is pitched as my maintenance notes indicate.

The Yanmar regional tech guys at Mastry say its the prop. The max prop guys say that if the pitch is as my records indicate then its not the prop.

I went over all of the gear and equipment we have added to the boat and my best guess would be that we have added about 2,000lb in overall weight to the boat. That includes a larger battery bank, a rear arch with solar panels, watermaker and various other gear plus all my tools and our cruising equipment. I cannot see it being much if any over 2Klb.


Terry

[s/v Thea]

Terry,

Have you measured the exhaust back pressure? That's not going to be expensive and could be your problem.

Doug

[never monday]

Originally Posted by Tspringer

So.... back to square zero. I guess we are down to 3 options at this point as far as I can tell: replace the injection pump, haul out and re-pitch the prop, go for a full rebuild or repower replacing the engine.

Terry

the IP is not the problem. Verify the prop next.

[Tspringer]

I have no means of measuring the exhaust back pressure. The mixing elbow is clear as is the hose leading from it to the fiberglass water lift muffler. The exhaust hose is huge in diameter and the water shoots out the transom exhaust as it always has. I cannot see how the exhaust suddenly got some sort of massive blockage and if it had would that not also increase the running temp?

I will ask the Yanmar dealer guys tomorrow about checking it somehow. My plan at this point is to get hauled out and check/adjust the max prop pitch down about 4 degrees.


Terry

[s/v Thea]

If the water is cool you might not notice increased temperature. You could probably make a manometer out of some clear tubing with water in it to measure the pressure. Probably isn't the problem but might be a good idea to rule it out before spending a whole bunch more money.

Doug

[farmerboy]

Hi there,
I am sat in a little farmhouse in Burtonwood (near Liverpool, UK) reading through the tails of woe regarding your engine!! I have just registered so I can post this . I really feel for you - it must be a complete nightmare... I have been messing with engines all my life - old tractors etc... and one thing I know is that if you keep at it you will get the better of it.

Not much practical help but if I lived a bit nearer I would pop round with my spanners and help out... I hope things start to get better in the engine department - keep at it and chin up!! Good luck and I shall be watching this space with great interest..

John (cruising "want to be" in the uk)

[svHyLyte]

Damn Terry,

I was sure you'd have this whipped by now. The only time we had a problem similar to yours was when we had a foul prop. But--you might have a diver check the prop to ensure the blades are fully deploying. If you've got debris in the works, the blades might only be rotating to a modest percentage of their fully deployed angle of attack in whch case they'ed stall and generate sufficient transverse loading on the blade surfaces to give rise to the conditions you describe. (A friend of ours had a problem with his Max Prop and it proved to be some debris in the gears that prevented the blades from fully rotating open.)

PM me with your email address.

s/v HyLyte

[Laidback]

Today Post # 93
"Max rpm at full throttle is 2,950 at which point the boat pours black smoke." Question :- without transmission in gear - at the dock what RPM could be achieved, same as before ? Next if possible at the dock with additional lines (rode will do) add more springs, engage reverse gear increase throttle until black smoke in quantity appears - record the RPM achieved. Then engage forward and do the same test. Another test is to run the engine in gear without the air cleaner's cartridge installed.
Was the new turbo lubricated in terms of the installation instructions?
----------------------------------
Go back to :-
Post #26
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.

However, this info was also in Post # 26

The engine will rev to 4,000 rpm at the dock not under load (out of gear).
------------------------------
The power curve for the 4JH2E HTE shows max HP etc at 3600 RPM - no higher RPM is shown in any of the engine's specs - Also note there is very little difference in gear and out of gear :-

[CharlieJ]

As I recall, you were only seeing 8.5 psi boost with the old turbo and you expected, or the spec was, 15 psi. Did the boost improve with the new turbo?

[Tspringer]

Laidback....

The Yanmar techs ran the engine to 4,000rpm in neutral, that was the max it would give in neutral. That is still the max it gives in neutral.

I ran the boat in gear while tied to the dock and the max rpm she will give in that state in forward is about 2,000 rpm with lots of black smoke. Away from the dock at max throttle we get the 2,950rpm and lots of black smoke.

I have not tried max rpm tests in reverse, may be able too tomorrow but what am I looking for?

Charlie.... the Yanmar techs took the old boost readings and they were not along for the testing of the new turbo today so I have no readings on the boost from the new turbo. But given that the max rpm is the same and the amount of smoke is the same my guess would be similar boost levels. Maybe I can have them test it tomorrow.





Terry

[Laidback]

Not to forget checking thermo control of Turbo cooling system - if not functioning to spec turbo slows down

[Captain Bill]

Terry, Turbo chargers are pretty simple minded beasts. Assuming they haven't physically blown apart (had a shaft break on one many years ago) then there is really only one reason they aren't developing proper boost and that is speed. There are basically three things that prevent them from spinning up to speed properly. The first is friction. They must be getting proper lube. The second is back pressure on the exhaust, which you have ruled out. The last is insufficient input energy. That could be because you are dragging a dead cylinder. My guess would be a bad valve. My 2 cents. Have you absolutely ruled out the last one?

[Chief Engineer]

What speed did you get at 2950?