Black Smoke - John Deer Engines

[jenglishsr]

All of a sudden (in somewhat colder than normal weather) we have had black smoke come out of our exhausts when under full load. We are being told that our props might not be set up properly (pitch, etc.). Being very much mechanically challenged, I am hoping that somebody might be able to shed some light on this for me. We've never had the smoke problem before; but then, we've never operated the boat in cold weather.

 

[Capt.Bill11]

Are the engines turbo charged?

 

[gaston]

we have had black smoke come out of our exhausts when under full load.



Both engines???????????

 

[jenglishsr]

Yes. Exhaust is from both engines.

 

[jenglishsr]

Yes. The engines are turbo charged.

 

[gaston]

Can only be fuel ?

 

[C lectric]

Full load, what specifically do you mean? Normal cruise rpm OR did you push the throttle all the way for max. rpm [WOT]? If full rpm , WOT, then have you done that before? What were the results before? What rpm was reached.?

By suddenly do you mean BETWEEN this run and the last run OR do you mean while you were out on this run and all of a sudden they started black smoking?

Cold weather should have no effect except to increase air from cooler, denser air, which the engine should like. Diesels like all the air they can get unlike gas engines.
.
Black smoke can be caused by several problems. It is almost always either overload or lack of air.
OVERLOAD
-props incorrect
-props fouled or damaged
-fouled bottom
-too much added weight which sneaks up compared to the way the boat was when new[er].

Since this happened suddenly and to both engines [ is that correct???] then I doubt the props are wrong but they could have been fouled by a line or seaweed. Not big enough to stall the engines but it would goof up the normal water flow and add a lot of load. Try a diver and get the props checked for fouling.

LACK OF AIR
-air filters, turbo, aftercooler, exhaust system,

Have you looked in the engine compartment.? At the air filters? If they are dirty that will cause insufficient air for the engines and black smoke. If you have an exhaust leak that will allow soot to plug the filters and that plugging can be quite quick. Soot should be quite noticeable. Regardless, Try changing the filters. It may be that plugging , if that is the case, reached a point where you noticed especially if you ran the engine a bit harder than normal. If this is the case then eventually it would have made itself known even at lower rpm.

I suggest checking/cahnging the air filter first since they are relatively cheap to replace and should be little effort. Also the diver as he/she too will be relatively cheap.
Some of the other things are going to take some work to do and some, possibly serious, expense to find and sort out.


Report back what you check and do.

 

[Insequent]

Full load, what specifically do you mean? Normal cruise rpm OR did you push the throttle all the way for max. rpm [WOT]? If full rpm , WOT, then have you done that before? What were the results before? What rpm was reached.?

By suddenly do you mean BETWEEN this run and the last run OR do you mean while you were out on this run and all of a sudden they started black smoking?

Cold weather should have no effect except to increase air from cooler, denser air, which the engine should like. Diesels like all the air they can get unlike gas engines.
.
Black smoke can be caused by several problems. It is almost always either overload or lack of air.
OVERLOAD
-props incorrect
-props fouled or damaged
-fouled bottom
-too much added weight which sneaks up compared to the way the boat was when new[er].

Since this happened suddenly and to both engines [ is that correct???] then I doubt the props are wrong but they could have been fouled by a line or seaweed. Not big enough to stall the engines but it would goof up the normal water flow and add a lot of load. Try a diver and get the props checked for fouling.

LACK OF AIR
-air filters, turbo, aftercooler, exhaust system,

Have you looked in the engine compartment.? At the air filters? If they are dirty that will cause insufficient air for the engines and black smoke. If you have an exhaust leak that will allow soot to plug the filters and that plugging can be quite quick. Soot should be quite noticeable. Regardless, Try changing the filters. It may be that plugging , if that is the case, reached a point where you noticed especially if you ran the engine a bit harder than normal. If this is the case then eventually it would have made itself known even at lower rpm.

I suggest checking/cahnging the air filter first since they are relatively cheap to replace and should be little effort. Also the diver as he/she too will be relatively cheap.
Some of the other things are going to take some work to do and some, possibly serious, expense to find and sort out.


Report back what you check and do.

+1

Go through these actions and you should resolve the problem. Key questions in red. This time was there full tanks of fuel/water, lots of stuff and people on board?

 

[FF]

Black smoke is more fuel than there is air to burn.

Overload is one possibility , a bad air intake or cleaner,a failed turbo or bad injectors will cause the same smoke.

 

[Insequent]

........ bad air intake or cleaner,a failed turbo or bad injectors will cause the same smoke.

True, but what are the odds of those things happening to both engines at the same time?

 

[FF]

Crap fuel will damage a High Pressure injection setup very rapidly if the filtering system is not 100%.

Do they have "summer " or "winter " blends of fuel where you are , perhaps there is a difference?

Does the smoke go away if the engine room is open?

 

[Capt.Bill11]

Are you sure your bottom and props are clean?

 

[Ski in NC]

Second that about fouled props and bottom. Absolutely the FIRST thing on the list to check.

 

[bayview]

yes the absolute first thing to check is bottom and prop cleanliness.

 

[stubones99]

Since cold temps is a complaint, I would check engine operating temperature (thermostats) and make sure they can get up to "operating temperature". Cold diesel engines smoke very black smoke due to incomplete combustion. It can't combust well due the glow plugs not getting hot enough to ignite the fuel cleanly

Stu

 

[Hawgwash]

While it is fun to spend time on the Miami, La Perouse and other Marin-izing threads, it's ones like this that are the backbone of this site. Every one of you posting here has added to my own mental KB.
Thanks.

 

[markpierce]

The only thing coming out of my John Deere's exhaust port is water and clear air. Haven't yet needed to outrun a mega-shark, however. (Engine is naturally-aspirated and bottom is inspected at least annually.)

 

[FF]

"Cold diesel engines smoke very black smoke due to incomplete combustion. It can't combust well due the glow plugs not getting hot enough to ignite the fuel cleanly"

Sorry,

Cold diesels that are just started or are not up to temp will exhaust WHITE smoke , which is unburned fuel.

A very good po boy check of engine compression is what coolant temp is needed to see the white smoke fade away.

Engines with pre-combustion chambers usually need glow plugs to START ,
but they do not usually operate while the engine is operating .

BLACK smoke is fuel that attempted to burn but was air limited

Bucky Balls.

 

[Hawgwash]

A very good po boy check of engine compression is what coolant temp is needed to see the white smoke fade away.

And the survey sez...what temp would that be Bucky?

 

[oscar]

It can't combust well due the glow plugs not getting hot enough to ignite the fuel cleanly

Stu

As said above glow plugs are for starting only, and some engines don't have them. My old Yanmar and the 2-stroke Detroits come to mind. There are others.

 

[oscar]

And the survey sez...what temp would that be Bucky?

Most of the old Detroit afficionados say 30 seconds.......

 

[Baker]

As said above glow plugs are for starting only, and some engines don't have them. My old Yanmar and the 2-stroke Detroits come to mind. There are others.

I would say MOST marine engines don't have them. I have owned 5 marine diesels(Volvo, 2 types of Perkins, Yanmar, Cummins) and none had glow plugs. I was told the higher compression engines(>18:1) do not have them installed.

My Cummins smoke like crazy when they are started in cold weather. But they clear up quickly.

 

[bayview]

folks might want to reread the OP

we have had black smoke come out of our exhausts when under full load.

Engines under full load are warmed up or will be very shortly.

 

[Ski in NC]

Glow plugs mostly only in small diesels with combustion chamber offset from cylinder. Kubotas, smallish genset engines, small sailboat engines, old Volvo tamd40, gm 6.2/6.5 v8, etc. Called precombustion chamber, prechamber, indirect injection, etc. Usually compression ratio is even higher, like 20-24:1. Most of these will NOT start unless preheated. Quieter under load, but lower efficiency.

Larger engines are direct injected, with nozzle spraying right into cylinder. Comp ratio 14-17:1 typical. No glow plugs needed to start, but some have air heaters to help when cold. Noisier combustion but much better thermal efficiency.

The trend is going away from prechambers, mostly due to poor efficiency. Not an issue with the really little engines, the efficiency penalty is not really a factor there. So little prechamber engines are still in production.

 

[stubones99]

"Cold diesel engines smoke very black smoke due to incomplete combustion. It can't combust well due the glow plugs not getting hot enough to ignite the fuel cleanly"

Sorry,

Cold diesels that are just started or are not up to temp will exhaust WHITE smoke , which is unburned fuel.

Engines with pre-combustion chambers usually need glow plugs to START ,
but they do not usually operate while the engine is operating .

I guess it depends on the engine...

Glow plugs are powered on cold days to preheat them to ignite the fuel. Once the engine is running, the glow plug tips stay red hot from the ignition of the previous cycle. you're sort of correct, in that they are not powered during operation of the engine, but that does not mean they are 'working'.

 

[Britannia]

As said above glow plugs are for starting only, and some engines don't have them. My old Yanmar and the 2-stroke Detroits come to mind. There are others.

My 1996 John Deere 6068T does not have glow plugs.

Richard
Stillwater KK54 #5

 

[koliver]

Your bottom and/or props may now be fouled to the point that you can n longer get to your normal full speed without overloading the engines.
EG: when I moved my boat from a shelter to open moorage for the summer months, the increased growth in two months covered my props (all running gear too) with 1/2" to 3/4" barnacles. I couldn't get above 5 knots without black smoke from both engines. Once the barnacles were removed, the smoke went away, even at over 8.5 knots (above normal cruise).

 

[River Cruiser]

Are you sure your bottom and props are clean?

I had the same problem a few years ago and it was a dirty bottom, no problems with the props in freshwater.


Sent from my iPad using Trawler Forum

 

[jenglishsr]

Reply to Thread re Black Smoke

Full load, what specifically do you mean? Normal cruise rpm OR did you push the throttle all the way for max. rpm [WOT]? If full rpm , WOT, then have you done that before? What were the results before? What rpm was reached.?

By suddenly do you mean BETWEEN this run and the last run OR do you mean while you were out on this run and all of a sudden they started black smoking?

Cold weather should have no effect except to increase air from cooler, denser air, which the engine should like. Diesels like all the air they can get unlike gas engines.
.
Black smoke can be caused by several problems. It is almost always either overload or lack of air.
OVERLOAD
-props incorrect
-props fouled or damaged
-fouled bottom
-too much added weight which sneaks up compared to the way the boat was when new[er].

Since this happened suddenly and to both engines [ is that correct???] then I doubt the props are wrong but they could have been fouled by a line or seaweed. Not big enough to stall the engines but it would goof up the normal water flow and add a lot of load. Try a diver and get the props checked for fouling.

LACK OF AIR
-air filters, turbo, aftercooler, exhaust system,

Have you looked in the engine compartment.? At the air filters? If they are dirty that will cause insufficient air for the engines and black smoke. If you have an exhaust leak that will allow soot to plug the filters and that plugging can be quite quick. Soot should be quite noticeable. Regardless, Try changing the filters. It may be that plugging , if that is the case, reached a point where you noticed especially if you ran the engine a bit harder than normal. If this is the case then eventually it would have made itself known even at lower rpm.

I suggest checking/cahnging the air filter first since they are relatively cheap to replace and should be little effort. Also the diver as he/she too will be relatively cheap.
Some of the other things are going to take some work to do and some, possibly serious, expense to find and sort out.


Report back what you check and do.

Thanks for your reply. By all of a sudden, I meant to imply that we have been on cruises both somewhat local and intermediate (San Diego to/from Catlalina) and we have not had a black smoke problem. The marine repair company that I am dealing with has indicated that they think that this is a prop setting problem; however, with no change in the props, I wonder how this could happen "suddenly."

This all started after, when my boat was taken out to get the bottom cleaned, the inspection indicated a problem with my struts and drive shaft. I got those issued fixed. Could the prop settings (I apologize if I have that wrong) have been disturbed during this repair process?

I appreciate your input and that of all of the forum members.

JE

I have checked the Air Filters and they are clean and in good order.

 

[FF]

"This all started after, when my boat was taken out to get the bottom cleaned, the inspection indicated a problem with my struts and drive shaft. I got those issued fixed. Could the prop settings (I apologize if I have that wrong) have been disturbed during this repair process? "

The "prop setting" the pitch, is only changed with great effort by hammering it in shape on pitch blocks

AHHHA!

If the shaft and struts are not properly aligned there could be enough extra load to overload at full throttle.

With the engine off , just how hard is it to turn the prop shaft in neutral?

The stuffing box will give some resistance , but with a screwdriver between the coupling bolts movement should be 10-30 lbs , not 100 + to move the shaft a full 360 deg.