Bluish smoke- oil or unburnt Fuel?

[jefndeb]

Hello,

Our single 2005 6LY2AN-STP, which has 3100 hours, has been well taken care of but this winter started smoking when cranked.

I had rotator cuff surgery and my wife had her Hip replaced so our boat needless to say has been at the dock for 6 months, but I run her every 10 days.

I've read that if its blue-ish smoke its oil, but I've also read/been told that a bad injector could cause unburnt fuel issues which is also a blue-ish smoke.
I also noticed a sheen of oil or fuel, cant tell, on the water coming from the exhaust.

I was advised the oil is probably from an internal turbo seal going bad, (allowing oil past) but if its un-burnt fuel its probably from a bad injector.

How does one pick a starting point to diagnose?

PS- that's me, on the front, trying to land my new to me drone like an idiot...lol?

 

[rslifkin]

If the engine has been run a bunch of times at the dock with no load on it and the boat hasn't been out, that may be part of the problem. I'd suggest taking the boat out and giving it a good run under load for 30+ minutes. See if the problem goes away after that. It's entirely possible the rings are a little gummed up from a bunch of runs with no load (and probably not getting things up to temperature well).

 

[jleonard]

If it clears up when the engine is up to temperature, I wouldn't worry about it.
You aren't going to get it up to temperature by running it at the dock.
And there is no need to run it every 10 days. Let it sit. Boaters up north let their engines sit several months while on the hard. (I did that for 30 years).
It could also be a touch over-fueled during cranking. It's got to go someplace.

 

[fgarriso]

If the engine has been run a bunch of times at the dock with no load on it and the boat hasn't been out, that may be part of the problem. I'd suggest taking the boat out and giving it a good run under load for 30+ minutes. See if the problem goes away after that. It's entirely possible the rings are a little gummed up from a bunch of runs with no load (and probably not getting things up to temperature well).

 

[Bmarler]

I wouldn’t run it again till you are ready to take it out and fully warm it up under load.
I leave mine unstarted during the rainy winter months when I don’t take the boat out. Been doing it that way for years.

 

[Pete Meisinger]

Starting your boat at the dock every ten days may sound like a good idea but it really isn't doing your engine any good.

Letting a diesel sit for a month or two does not harm it. What you should do is get the boat out on the water every month or so and run it hard and long. It will show it's appreciation by giving up smoking.

pete

 

[STB]

Blue-ish smoke indicates that a noticeable amount of oil is being burned by the engine. It can also leave a slick on the water, often with a rainbow-like appearance.

Grey or black smoke indicates that the fuel isn't being efficiently burned and there are a bunch of hydrocarbons there, not just CO2 and water. In a very simplified world, diesel burns as C13H28 + O2 = CO2 + H20. The less efficient the burn, the more hydrocarbons in the exhaust. The more grey-to-black the smoke looks

White smoke that floats away quickly and has no smell to a sweet smell is often coolant in the exhaust.

White smoke that tends to linger and may have a bitter or burning smell and may leave a slick on the water tends to be unburned diesel

If there is blue and grey smoke or blue and black smoke, one tends to see it as a darker grey color with some blue in the darker areas.

White smoke can obviously lighten dark smoke, but the tell is often the slick.

Since blue smoke is oil getting into the combustion chambers, it can be a sign of an engine with some hours on it, a problem with the oil control rings in the engine, a turbo leaking oil into the air and back into the engine, an over-filled oil system leading to the foaming of oil and it getting where it doesn't belong, etc, etc, etc.

White diesel smoke is normally a sign of a poor injection pattern which can result from one or more bad injectors, a bad injector pump, a bad lifter pump, clogged filters, clogged or degenerated fuel lines, valves that aren't completely closed, etc, etc, etc. Basically, anything that can lead to a bad spray pattern.

White coolant smoke is most often caused by a failed head gasket letting coolant into the combustion chamber, but can also be caused by other, more serious, problems.

Dark grey or black smoke tends to be a clogged air intake or other induction system construction, especially on a turbo; a bad turbo not pushing enough air; a somewhat tired engine that doesn't have enough compression to efficiently burn the fuel; or overpropping, a dirty bottom or running gear, or some other form of overloading that is preventing the engine from getting to the RPMs needed to burn the fuel efficiently and completely. If there is excessive blowby, e.g. air coming out of the dipstick or crankcase oil fill when the engine runs, this can be a sign of a worn engine vs overloading, etc.

 

[jefndeb]

Much appreciated, I plan to take her out tomorrow to run her for an hour under load and see what happens...

 

[Comodave]

Much appreciated, I plan to take her out tomorrow to run her for an hour under load and see what happens...

That is a good plan. Then don’t start it and run it unloaded regularly. My diesels sit 6 months over the winter and start immediately in the spring.

 

[OldDan1943]

When I run my engine at the dock, I also exercise my running gear so, it is under load. It might take an hour or two.

 

[Delta Riverat]

I don't start the engines just to see them run. I will start the engines and run for a short time after a filter change to see oil pressure and a clear fuel line. I had to start one engine twice after a filter change as there must have been some air still in the line.

But that aside, if I'm starting engines we're off to a boat ride.

 

[rslifkin]

I don't start the engines just to see them run. I will start the engines and run for a short time after a filter change to see oil pressure and a clear fuel line. I had to start one engine twice after a filter change as there must have been some air still in the line.

But that aside, if I'm starting engines we're off to a boat ride.

Agreed. Engines get run to move the boat or as needed for maintenance activities, but not just for the sake of running them.

 

[jefndeb]

Hey,

Here are 2 videos of today's sea trial.

One looks kinda blue-ish, as it did at the dock and later, (it might look blue to me because its more in a shadow than the second clip is)

On the way back i took another shot that looks more white but seems to be more smoke than I've ever seen...

I ran her way hard as well...

 

[STB]

Hey,

Here are 2 videos of today's sea trial.
One looks kinda blue ish and later, on the way back i took another shot that looks more white but seems to be more smoke than I've ever seen...

I ran her way hard as well...

This is one where it is a bit hard to tell. But, the difference in the two videos is dramatic.

When it was smoking grey at the beginning, how much throttle was that? What rpm? Was there an egt or boost gauge?

Basically, if it was running cleaner and then smoked up like that toward the end of its output, it could just be overloaded. A little too much prop pitch for the boat configuration, dirty bottom, a little aging, etc.

If it was smoking like that at a lower throttle setting, it could be low compression, low boost, low air, bad fuel, valve timing, etc.

But, it did clean up later, either because of a different throttle setting or because it needed to be run to clean itself out or because compression improved with the warm up.

If this had been an active boat, it is what it is. If not, in an ideal world, I'd want to tale it out again to understand if it did better for being run for the 1st time in a while or if the smoke is related to warm-up or throttle setting or both.

As for the 2nd picture, the combustion had cleaned up a lot, obviously. There are two possibilities for that white smoke. One is diesel and one is steam. I can't quite tell from the video.

If you came back and slicked the marina, that woukd be a tell. If you came back lownkn coolant, that woukd be another.

That much diesel would be very surprising at any reasonable cruise throttle setting. It is just hard to not get it somewhat burned. But, if you've got one bad cylinder and others are all good, etc, it can happen. What it did at the slip would be a tell for me.

That is a high output turbo engine with an intercooler, I think. What was your EGT? That could just be steam from hot exhaust. Did it do that the whole way back?

If that was me I'd have backed down on the throttle to let it cool off and see what it did. Did it clean up? Or did it go back to black? Or did it stay white?

What did you observe at the slip after docking?

 

[jefndeb]

I ran her today at 3000 RPM and when we got back to the dock, there was very little if any noticeable smoke while at idle.

 

[STB]

I ran her today at 3000 RPM and when we got back to the dock, there was very little if any noticeable smoke while at idle.

Okay. That is good.

I guess I'm now curious about the smoke during the other bits of the trip.

 

[jefndeb]

I don't have a boost or EGT gauge,

 

[STB]

How did the smoke look during the rest of today's ride? Better? Same?

 

[jefndeb]

The trip back was pretty much just as the video shows (more white steam looking).got to the dock and couldn't really see much of anything as far as smoke...now I don't know what to do

 

[STB]

Okay. So there were two trips out, yesterday and today?

How did the two differ w.r.t. smokies, if at all?

What is the coolant level? Have you lost any? If so, how much?

 

[jefndeb]

No, the fist video is the trip out of the marina out into the sound, second video, is where we turned around and headed back in.
Didn't check the coolant yet.

 

[STB]

Okay. So. I'd check things over well on the inside and, assuming you don't find any problems, take it out for another run. Things may have improved since your last trip out.

See how it starts, what the smoke is like at start. Run at cruise speed for a while until warmed up. Then slow it down to idle. See how it looks. After a minute bring it up to a fast idle. Then a slow cruise. Then a fast cruise. Then start to bring it up incrementally to WOT. See, for example, if there is a point where the white smoke goes away, or it starts up, or it starts getting a little grey, or it gets really dark.

The idea is to see if warming up is making things better; if getting up to some minimum rpm is burning the unburned fuel; if getting up to a certain RPM is getting the turbos to kick in, heating things up, and make a bunch of steam; and/or if after a certain point the smoke starts to get a lot darker but the boat isn't going much faster or isn't gaining rpms with increased throttle.

Then, back it back down and see it there is any hysteresis. In other words, see if it performs any better or worse at the same throttle settings on the way down then it did back up.

You don't need to push it liller hard for long. Or past the point where it gets unhappy. The idea is to find the limits and their symptoms.

Once you know that, it is easier to diagnose things, I think.

And, if the whole of the problem happens to be that it needs to warm up, then you can decide what you want to do about that. If the last time you ran the boat was a Georgia summer. And now you are running the boat in a Georgia January -- it is going to perform differently! I think, at the least.

 

[rslifkin]

That white stuff in the second video is almost certainly steam. It looks and moves like steam. Especially if the weather was a bit cool and humid, seeing steam under heavy load isn't necessarily abnormal. Some engines do it more than others, and exhaust design is a factor as well.

 

[STB]

That white stuff in the second video is almost certainly steam. It looks and moves like steam. Especially if the weather was a bit cool and humid, seeing steam under heavy load isn't necessarily abnormal. Some engines do it more than others, and exhaust design is a factor as well.

That seems way more likely to me, also. Especially since it reportedly was all cleaned up with no slicking once it cooled down and was back at the marina.

Overfueling usually gets worse at low throttle settings, not better.

Steam usually gets better when cooler, not worse.

 

[Lou_tribal]

Was the weather cold? On our boat we can get steam during cold season end in october when temp is cold.
Second thing how is your water exhaust, does it throw a good amount of water or just steam? Once we got a torn out impeller that was barely able to pour enough water in the exhaust what resulted in more steam than normal while was enough to keep engine at normal temp.

L

 

[brianaderer]

No need to run every 10 days. Better to leave it off unless you're going to work it. If it's gonna be down for a while then stabilize the fuel, put the battery on a maintainer, and let it be. Most of the wear is done during the warm up phase, so just turning it on for the sake of it is about the worst thing you can do

Hello,

Our single 2005 6LY2AN-STP, which has 3100 hours, has been well taken care of but this winter started smoking when cranked.

I had rotator cuff surgery and my wife had her Hip replaced so our boat needless to say has been at the dock for 6 months, but I run her every 10 days.

I've read that if its blue-ish smoke its oil, but I've also read/been told that a bad injector could cause unburnt fuel issues which is also a blue-ish smoke.
I also noticed a sheen of oil or fuel, cant tell, on the water coming from the exhaust.

I was advised the oil is probably from an internal turbo seal going bad, (allowing oil past) but if its un-burnt fuel its probably from a bad injector.

How does one pick a starting point to diagnose?

PS- that's me, on the front, trying to land my new to me drone like an idiot...lol?

 

[rgano]

Those two videos looked to me like wintertime condensation, not smoke. My 6LPA-STP will do that in the cold months. Heck even my old Ford-Lehmans did that in coolish weather. Stop worrying. Take another video in July for comparison, and I'll bet you see nothing.

 

[Sleeping Bear]

Looks like steam to me, is the impeller good, and the strainer clean?

 

[STB]

Just to provide a synopsis for newcomers to the thread. I think the consensus is that the early photo of dark smoke was caused by "needed to run" as evidenced by the later photo which showed that running cleaned it up to white smoke.

And that the latter photo likely shows steam vs fuel and that itnis most likely seasonal, but that prudence suggests also checking the impeller, etc, to ensure good exhaust and cooling system performance.

 

[ronobrien]

If the engine has been run a bunch of times at the dock with no load on it and the boat hasn't been out, that may be part of the problem. I'd suggest taking the boat out and giving it a good run under load for 30+ minutes. See if the problem goes away after that. It's entirely possible the rings are a little gummed up from a bunch of runs with no load (and probably not getting things up to temperature well).

+1