White smoke in the exhaust

6

63chaos

New Member
Mar 6, 2011
63
Falmouth, MA
Boat Info
300 Sundancer 1993
Engines
5.7 260 hp (2)
Fired up both engines today the starboard one seems to have some white smoke in the exhaust. I just replaced the manifolds and risers on both. Is this something I should be concerned about, could it be a head gasket, if so how do I verify that? Thanks any advice would be great.
 
Need more info. Fired up for the first time this season? Or has it been running fine until you replaced the manifolds/risers? Yes, white smoke should concern you. It means that you are compressing/vaporizing water for some reason. If this is a first start, then it could very well be the fogging oil burning off. Is the white smoke constant, or intermittent? Is engine stumbling/coughing at idle? Please provide more running condition symptoms. Did you use the expensive (quality) Mercruiser spec metallic riser gaskets, or the cheap green paper/cardboard ones?
 
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Do you have a closed cooling system? Antifreeze will also create white smoke when it burns.
 
This was the first time running with the new manifolds, I did use the good metallic gaskets, I did check the dip stick for any signs of water I don't see any, It seems to run great at idle and revs up with no problems. Everything sounds normal the white smoke dos'nt have any kind burning smell and it is constant.
 
If temp is good and everything seems to b running ok then I would run them a little more before being concerned. Whenever a metal is casted or bent or formed into a different shape (manifold and risers being built or "formed" the metal is brought up to Very hot temp (around 2500 degrees to be poured into its form to actually make a mold) it its them dipped into oil to cool it so the metal keeps its strength. (dipping into water depreciates the strength of the metal by more than half) the metal actually absorbs some oil and an oily film is left on the inside surface (outside surface is blasted and painted) when the manifold and risers at heated up the oil Burns off giving you the white smoke. All exhausts do this even cars just most people don't notice. Just be cautious while running And see if itgoes away. To b extra cautious I would pull plugs one by one to c if there is any water off white spots or fouled plugs do to water intrusion
 
Xplicitlnck said:
If temp is good and everything seems to b running ok then I would run them a little more before being concerned. Whenever a metal is casted or bent or formed into a different shape (manifold and risers being built or "formed" the metal is brought up to Very hot temp (around 2500 degrees to be poured into its form to actually make a mold) it its them dipped into oil to cool it so the metal keeps its strength. (dipping into water depreciates the strength of the metal by more than half) the metal actually absorbs some oil and an oily film is left on the inside surface (outside surface is blasted and painted) when the manifold and risers at heated up the oil Burns off giving you the white smoke. All exhausts do this even cars just most people don't notice. Just be cautious while running And see if itgoes away. To b extra cautious I would pull plugs one by one to c if there is any water off white spots or fouled plugs do to water intrusion
Click to expand...

I found that very interesting xplicitlnck and learned something new today. Thx :)

Terry
 
Anytime. I'm not that good with boats mechanics yet. First year with a real boat (last one was a jet boat) but I'm learning alot from this website. But I am an iron worker and know alot about metal so I try to help those who help me. Goodluck and enjoy your holiday weekend
 
Thanks I hope that's it I will pull each plug and check them one at a time, what am I looking for, what would a water fouled plug look like?
 
Water usually show up as very white plugs, like they have been steam cleaned (which they have if you are 'burning' water).
 
I noticed that while we were up with the boat this weekend i had white smoke comming from the starboard engine as well. It doesnt seem to be constant, only when the RPM is about 3000 and it just streams out the exhaust. Dont even see any at an idle or a low cruising speed. If it it water intrrusion what does this entail ? New manifolds/risers, more ???
 
Also forgot to add, the starboard motor wont give after about 3k rpm or so and the throttle is fully forward while the port throttle and motor will just give give give and is only engaged 1/2 to 3/4 of the way forward.
 
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