Smoke from Air Cleaner

[SV Hope]

After our first oil change, we turned the engine over with the engine stop leaver engaged as was suggested. After a few seconds smoke started coming from the air filter? Is this normal and why would it have happened?  Please excuse my inexperience but any ideas would be appreciated. 
Another question from the inexperienced, why is there what looks like a fuel line running into the air filter case? Thanks Samantha

[RayNWanda]

Samantha, which engine do you have?

[Dale Tanski]

Samantha,
I wouldn't recommend that you turn the engine over with the stop lever engaged unless the boat is out of the water or your raw water inlet valve is closed.  I say this because each time the engine turns over, the raw water pump pumps water through your heat exchanger, into the cooling jacket on the exhaust manifold, and out to the exhaust mixing elbow.  At the mixing elbow, the exhaust gasses and the raw cooling water mix to cool the exhaust and enter the wet lift muffler. The water is lifted out of the boat and removed by the pressure from the now cooled exhaust gasses.  The entire system is below the waterline until the wet exhaust is lifted up and out.  When you crank the engine over and water is allowed to mix with the exhaust, if there isn't enough back pressure to lift the water up and out through the muffler the water can back up into you engine and real bad things can happen as water does not compres.  The expansion of the exhaust gasses from the burning diesel fuel which is what powers your boat, is required to lift the water up and out of the muffler.  If the engine isn't "running" water intrusion back into the engine is possible.

As for smoke out of the air inlet... was the engine hot when you changed the oil?  Was the smoke white? If so water could have splashed back through the exhaust and flashed into vapor or steam. 

If we are talking the 4-107 Perkins engine the hose you see running from the rocker cover to the air inlet is a vent for the crankcase.  If there is blow by from compression, that pressure is vented back to the beginning of the system (air inlet) and recycled so to speak.  The older (more worn) the engine becomes the more blow by it will have.

Dale

[SV Hope]

Original Westerbeke W40 engine with complete replacement of the Bottom End with a much newer Perkins 4-108 model. The smoke was white.

(This yacht was previously Known as "Dosia" and was flooded just as you described we think, that is why it has a new bottom end, she is now in Australia)

I think I worked out the fuel line is going to the Thermostat Devise for the cold start Aid. (Just need to find out how that works now). Could the smoke be from overheating of the thermostat? 

For next time, can we just start the engine normally after an oil change?

[Dale Tanski]

Samantha,

I do remember talking to Drew about this problem well over a year ago.  As I remember, he had a problem starting the engine after putting it back in the water after a long term layup I think in South America, and I do believe he did flood it back.  I also remember something about a rocker arm issue. 

Can't comment about the thermostat start aid.  That is a good question for Ray (commented above).  He is a hard core diesel guy and will know the answer for sure. We love you Ray....

After an oil change you should start the engine as normal.  There will be a few seconds that the engine will not get full oil flow while the oil pump fills the new oil filter.  If you had a 10 million dollar yacht, it would have an electric driven lube system pump that would establish oil flow before the engine would turn over minimizing any chance of internal wear. 

Overheated thermostat... hum... The thermostat controls the coolant flow to the engine to maintain it at its required normal operating temperature.  That is somewhere between 160 degrees F and 180 degrees, depending on the thermostat rating.  It opens and closes automatically to adjust the coolant flow. When the engine is cold, the thermostat is closed.  As the engine warms up the thermostat begins to open allowing cooling water to enter the engine maintaining the required temperature.  Thermostats are mechanical items and very seldom fail closed.  Closed would be very bad as overheating will indeed occur.  Most of the time they fail open.  This means the engine runs cold or below temperature. When this occurs, small amounts of water could accumulate in the crankcase oil from condensation and you will not get very good fuel milage.

Dale

[SV Hope]

Dale,

I don't think there is anything wrong with the water thermostat. For some reason the manuals call the device for the cold start Aid (on the side of the air intake manifold) a thermostat?  From what i gather it vaporizes fuel to help with easier combustion...

Thanks for your advise, I am just slooowly trying to work out how this big red thing works as I believe you should be as self reliant as possible on the water. Off to the yacht today to see how she is, with a mechanic (hopefully he won't mind explaining things to a female).

I have a long way to go I think, but it's all about the journey.

Samantha

[barrylab]

As I understand it, the item you are referring to is the equivalent of glow plugs. You push a button somewhere (mine is next to the start button) and it heats an element that gets fuel misted onto it when you hold the button down while pressing the starter. This is sort of a poor man's glow plug, and serves (pretty much) the same purpose.

[RayNWanda]

 I can understand where somebody might think it a good idea to roll the engine with the starter and build some oil pressure before starting it. It sounds like it would be less wear and tear on the engine, and in some cases it might be. However in this case, we have an engine with a water lift muffler and the exhaust hose from the muffler to the transom is higher than the mixing elbow. This exhaust system is DEPENDENT on exhaust gas flow to push the water out of the muffler and exhaust hose. If the engine is not running, it ain't gonna happen. The water will follow gravity when you let off the start switch and what is at the bottom of the hill is the engine. During a normal start, the engine turns a few revolutions and (hopefully) starts. I always used the "two tries" rule. If the engine did not start on the second try, I closed the seacock until it did start. The water pump impellor is wet, it will be fine. Just get the seacock open immediately after it starts. Ours always started quickly, the exception being after a fuel filter change.
I do remember Drew mentioning that his girlfriend? flew down somewhere to meet him with a complete rocker shaft and maybe a set of pushrods.
The cold start thingie- It is a little heater inside the intake manifold to warm up the air. I have seen some on other engines that also had a little fuel sprayed on them to atomize the fuel with heat. The fuel then looks just like- you guessed it- white smoke. Crankcase vapors also look like white smoke. I suspect you saw the "smoke" when you let off the starter? Usually the engine will rock backwards a partial turn when you let off the starter and the engine is not running. It is just enough to push some crankcase vapors out of the air intake.

[Jim S]

I agree with RaynWanda about the source of the smoke.  The vaporized fuel will blowback and can be visible.

[SV Hope]

Thank you all for the advise.   

The mechanic was great also, yes the "smoke"  is good vaporized fuel, nothing to worry about, so got some help with checking fuel lines while he was there.

It didn't help that we had also cleaned the air filter and this is what made it VERY visible. It's a bit embarrassing, it must have seemed obvious to those in the know, but thanks for all of your help.

New mechanical adventure with a noisy V Drive now.

Samantha