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Author Topic: Engine smoke  (Read 2386 times)

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John Langford

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Engine smoke
« on: November 23, 2003, 04:39:39 PM »

We just had a very successful sea trial of the 1999 C34 that we are trading up to. It sailed smoothly and quickly in 16 knots of wind. But I have one question.
 
 Should there be any smoke coming out of the Universal M35 exhaust at about 2500 rpm? The weather was cold (about 7 degrees celsius) and the air was damp. There was a curl of white/grey smoke which soon dissipated but it looke like more than condensation. The only other relevant information is that the motor is driving an autoprop, it only has 625 hours on it and it looks well maintained.
 
 I'd be grateful for any feedback. The Perkins on my C320 has never shown even a whisp of smoke.
 
 Cheers,
 John Langford
 Victoria, B.C.
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Cheers
John
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Ranger Tug, 29S

Mike Smith

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Engine smoke
« Reply #1 on: November 23, 2003, 05:24:35 PM »

Hi John -
 
 I'm no diesel engine expert (there are others on this board who are) but I know the color of exhaust is very diagnostic of possible problems with the engine. The exhaust of a properly functioning diesel engine is clear. If it is not, it is either black, blue, or white. If the exhaust is black, it is an indication of incomplete combustion of diesel fuel, and indicates an air starved engine, usually due to a clogged air filter or other obstruction in the air supply system. It also may occur when the engine is suddenly put under load and dissapears when the engine is throttled back, but even then it should be checked out. If the exhaust is blue, it is an indication of burning engine oil, usually caused by such things as cylinder compression problems, rings for example. This is problbly the most serious indicator and usually persists the entire time  the engine is running. If the exhaust is white it is an indication of the presence of water in some form in combination with the diesel fuel. It is essentially condensed steam or water vapor. This is the most transient condition and is typically experienced at startup and then it quickly dissapates. I'll go out on a limb and say it is a normal condition and usually not a problem.
 
 Congrats on your new boat,
 Mike
 
 PS I have a Perkins M30 on Breezer - great little engine!
 
 Mike and Jan Smith
 S/V Breezer WCX8545
 www.mikejansmith.com
 
 [This message was edited by Mike & Jan Smith "Breezer"  '88 #688 on November 23, 2003 at 05:33 PM.]
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Stu Jackson

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Engine smoke
« Reply #2 on: November 23, 2003, 07:27:52 PM »

John
 
 625 hrs on a 1999 engine is about 125 hours per year, which is normal use for a recreational boat.
 
 You've already looked at the C34 FAQs, but my favorite quote is from AQUAKON (thanks to John) that goes:
 
 "My experience has been that a close observation of the seller and those things surrounding them can often give a clue as to the seller's approach to care & maintenance in general. Rare is the person who lets their car stay dirty, with leaking oil, grating brakes, etc., while meticulously caring for and maintaining their diesel engine & fiberglass boat."
 
 So, what's the seller's car and house and spouse look like?
 
 If the rest of the boat is AOK, you should not worry too much.
 
 As Ron suggests, have you run it up to spped and temp?
 
 Good luck, but also, if you'r unsure, get a mechanic, beyond your surveyor, to check it out.
 
 I know you're trying to buy a boat and probably don't have time to read this entire website, but I KNOW it's all been discussed before.
 
 GOOD NEWS:  it's RARE that anyone's reported problems of ANY kind (other than the water pump) on a boat as new as 1999)
 
 Stu
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Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

"There is no problem so great that it can't be solved."

John Langford

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Engine smoke
« Reply #3 on: November 23, 2003, 08:48:21 PM »

Thanks Folks,
 I did not look at the temperature when it was smoking (white smoke) and we only ran the engine for 20 minutes each direction so I can't say if the engine was operating at its optimal temperature.The engine had been sitting for a month before it was run.
 
 Ron, I am not sure I understand the max rpm issue.
 
 Cheers,
 John
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John
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Ray & Sandy Erps

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Engine smoke
« Reply #4 on: November 24, 2003, 10:32:44 AM »

White smoke (steam) is an indication that the raw water pump isn't pumping enough water into the exhaust to cool it down enough to prevent steam.  I've had some white smoke twice with two different boats.  Each time the raw water strainer was plugged with eel grass, restricting the raw water intake.  The engine temperature was also a little on the high side.  Look to see how much water is coming out with the exhaust, always the first thing I do after starting my motor and confirming I have oil pressure.
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Ray & Sandy Erps,
'83, 41 Fraser "Nikko"
La Conner WA

saltydog

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Engine smoke
« Reply #5 on: November 24, 2003, 02:49:26 PM »

John
 Also have an M35 engine with 890 hrs. Have noticed similar smoke under conditions you described for short time until engine warms up. Believe normal at cool or cold air temps and high humidity. Otherwise, engine never smokes.
 Jeff
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jentine

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Engine smoke
« Reply #6 on: November 24, 2003, 04:46:49 PM »

I went to the Sound last weekend and winterized my boat since it is beginning to get cool in New England.  I started the engine and observed white "smoke" from the exhaust.  It is normal in cold weather to see wisps of condensation from the exhaust without any inherent problem (my car does it all winter).  I would not worry about a little white smoke from the engine on such a cold day.  When the engine reaches operating temperature, it should go away.
 Black smoke is unburned fuel, usually from an overloading problem; blue smoke is burned oil, usually a problem; white smoke us water vapor, usually not a problem unless it does not go away and is associated with loss of coolant.
 Jim Kane
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