Steam/Smoke - M35B

[Joe Kern]

Looking for some suggestions.  I have searched these Boards as well as the M35B owners manual, numerous websites and books and have gotten a variety of answers.  I have a list of things to try but thought I would at least see if anyone here has experienced this problem especially on a M35B.

I have about 300 hours on my engine.  I have done all the required maintenance.  Sometime over the past few months I started noticing a little bit of what appeared to be steam/white smoke after the engine had been running for awhile. Seems to be a function at load and more steam at higher revs.  Since the weather was pretty cool I was sure it was just steam due to the temperature difference.  Now that things have warmed up it has not gone away.  I have not noticed any difference in power, no coolant loss and no smell from the exhaust.

It is definitely not black smoke.  I think it is more steam-like than what I would call white smoke but not really sure what the difference is.  Definitely fairly wispy.  No fuel coming out that I can see and the water flow seems good.  Does not start out with any steam/smoke but comes on after the engine warms up.

I have seen suggestions running from checking the raw-water circuit, water in the fuel, fouled prop causing too much load to things like head gaskets, injector problems and other bad stuff.  Some have said the steam/smoke comes from not enough water mixing with the exhaust gasses.

I am going to check/change the Racor, clean the raw water intake, try and take a look at the prop.  Plus other things to check based on my frantic web-searching. 

Anyone had any similar problems they have solved and can suggest for me?  Hoping to avoid an engine service call on a pretty new boat but will do it if I have to.

Thanks.

[rirvine]

If it is steam, check the heat exchanger.  Over time the heat exchanger zinc material will block the cooling tudes causing a reduction in the raw water flow.  You can inspect the tudes by removing the end caps on the heat exchanger - after you have disassembled the rear of the engine box.

Ray

[Mike and Joanne Stimmler]

Is your engine temp normal and have you found anything in your raw water strainer. While you have the strainer off, open the through hull for just a few seconds to make sure you have good water flow coming into the strainer. A starting point if you havent already done this.
During the sea trial when I bought the boat, no one thought to open the sea cock and we had major overheating with steam included.

Good Luck,
Mike

[Stu Jackson]

Another item to check would be the inlet hose on the exhaust riser to assure good cooling water flow from the engine where it mixes with the exhaust gases before it goes into the muffler.  This includes the anti-siphon valve on the hose from the engine to the water inlet pipe to the exhaust riser.

You seem to have a good start on this, just check every single component of the cooling system, step-by-step.

[miken]

Joe,

I had the same steamy/smoky/misty experience last year on a long motor in flat water (probably wouldn't have noticed otherwise) The engine had been running for a couple of hours and engine water temp was well within normal range. Nosing about the engine compartment found no odd or burning odors. I monitored the rest of that trip and frankly forgot about it until your post. I'll be look into some of those suggestions mentioned above as launch nears. Our M35B has approx. 450 hours

Mike
2001 34 MKII
1570
"Alma Viva"

[Ron Hill]

Joe : The steam and white smoke could be nothing.  You mentioned the cool weather.

White smoke - usually means unburnt fuel that be caused by excessive fuel or poor combustion.
Steam - steam or water vapor will rise and clear fairly quickly, whereas smoke tends to stay closer to the water and takes longer to dilute.  Usually caused by cold conditions or insufficient raw water flow.
Some thoughts.