Yanmar diesel smoking/ black soot

[Bronk33]

Hey everyone!
I have a 1973 Pearson 30 with a yanmar 3gmd.
I took a long trip a few months ago. Had to motor sail half the way back.
Well, the alarm wasn't plugged in so I didn't hear the motor was overheating (impeller damage).
Not exactly sure how long the motor was overheating, but it did damage. I'm surprised it didn't blow up.
The sea strainer melted and the water muffler melted.
Those were the noticeable damages. Replaced both.
At this point, the motor runs but on startup a good amount of black smoke and black door (unburnt fuel) come out. If I run it at 2500-3000 Rpm for about 5-10 mins, the black clears. Until I put it in gear. Then while in gear, it will smoke and soot the entire time.
I checked the fuel lines, and changed the 3 injectors.
No change.
This has only happened after the overheating incident.
Friday, I have someone coming out to clean the bottom and check prop buildup, but that won't have anything to do with smoking and soot and startup.

What are my possibilities? I started up (for seconds) without water muffler attached and black smoke was thick. Another ailment is the motor is slow to decelerate and to shut down.


Sent from my iPhone using Cruisers Sailing Forum

[Bronk33]

Sorry, black smoke and black soot***


Sent from my iPhone using Cruisers Sailing Forum

[BruM]

Is it using lube oil???

[sailorchic34]

To me, it sounds like the injector pump, needs a rebuild or the governor is not working right

[River Cruiser]

Black smoke is caused by to much fuel or to little air. You've replaced the injectors and should be able to eliminate them as the problem, check the air filter if equipped be certain it isn't restricted. Then if your engine has a turbo I would check it next. Check the clamps and tubing on the air end of the turbo for leaks, make sure clamps are tight and no leaks in the plumbing. If you find no problem on the air end plumbing then remove the air end plumbing and check that the turbo shaft is free to turn no drag. Does it have the black smoke issue in gear and in neutral? If only in gear the prop may be fouled.


Sent from my iPad using Cruisers Sailing Forum

[a64pilot]

How about power, is it way down on power, as in just won't turn near the RPM in gear that it used to?
That motor does not have a turbo does it?

[Bronk33]

Originally Posted by a64pilot

How about power, is it way down on power, as in just won't turn near the RPM in gear that it used to?
That motor does not have a turbo does it?

I would say power is definitely not as strong. And like I said, slow to come up and down on Rpm.

There is no turbo.


Sent from my iPhone using Cruisers Sailing Forum

[Bronk33]

Originally Posted by sailorchic34

To me, it sounds like the injector pump, needs a rebuild or the governor is not working right

I was leaning toward the fuel injection pump or fuel feed pump. Because of the black soot that's coming out with the smoke. I'm guessing it's just dumping too much fuel in.

Are there tests outlined for these somewhere? Without sending them in.


Sent from my iPhone using Cruisers Sailing Forum

[jimbunyard]

Exhaust restriction exacerbated by the overheat perhaps?

[sailorchic34]

Originally Posted by Bronk33

I was leaning toward the fuel injection pump or fuel feed pump. Because of the black soot that's coming out with the smoke. I'm guessing it's just dumping too much fuel in.

Are there tests outlined for these somewhere? Without sending them in.


Sent from my iPhone using Cruisers Sailing Forum

If I remember correctly, there are a few tiny o-rings in each injector in the pump . I'm betting they went gone with the wind when the engine overheated

[gah964]

Originally Posted by sailorchic34

If I remember correctly, there are a few tiny o-rings in each injector in the pump . I'm betting they went gone with the wind when the engine overheated

its not the injectors its a cracked ring

[lookinggoodrock]

Yup, I believe cracked rings also. Usually too much fuel would be white smoke.

[Bronk33]

I'm reading the Repair manual about fuel timing.
Does anyone know of a write-up on taking apart, repacking, servicing the fuel injection pump?


Sent from my iPhone using Cruisers Sailing Forum

[sailorchic34]

Nope, too much fuel is black smoke or injector timing, but timing is not effected by temperature.

My engine has a piston with three broken rings it did not smoke at all. Used oil like a pig, but no smoke.

Blue grey smoke is oil, white smoke is water.

[a64pilot]

While it could be injection pump, and the it takes some time to slow down really seems to point in that direction, since it was badly overheated I'd want to do a compression check to see if there is any damage like cracked head, blown head gasket, etc.

Almost sounds as if it's partially seized, hope not of course.

How much run time is on it since the overheat?