Merc 8.1 white smoke/steam?

[TFD2001]

Headed out Friday night on our local place, ran to a cove with others, and parked there for several hours, then moved up the lake a little ways and parked there for the night. Had no issues on either run, second run was maybe a 15 minute run. Got up the next morning and ran up the lake a little further, temperature change outside had dropped and it was on the cooler side. Running about 2800 RPM and noticed the starboard engine pouring out what I felt was abnormal amount of white exhaust, slowed her back down, and exhaust cleared more or less, and at idle was no exhaust and water flow looked good. All temps on the motors were good during this time, and everything seemed to be running well and as expected.. Continued to our destination at a slower cruise around 1500-1800 RPM, no exhaust showing.. Arrived at our destination, put her in neutral, and ran the RPMs up under no load to 2500 and saw no smoke/steam? Sat on the hook for the day, and then headed back mid evening to the dock in anticipation of the rain coming in the overnight. Again, at the 2800 - 3000 RPM range, the white smoke/steam returned but I pushed her on up past 3200 RPM and it went away, or became un-noticeable? Port engine was exhibiting similar things, but just wasn't as viewable to me, or wasn't doing it as bad.. Again, all temps looked great, no alarms, and motors running as good as ever. No vibrations or anything. I checked the oil the week before just out of normal checks, and noticed no issues with it's color or being low.. We had a rain out Sunday, and I was doing other things and failed to go check the oil then. I want to say it was just the change in temp and the exhaust showing from that like your car does in cooler temps, and but this just seemed significantly more than what I'm used to seeing with that? The glass half empty guy in me says a head gasket but that seems awful sudden? This is a new to us boat this year, but we had everything gone through after purchase and ALL rubber in the bilge was replaced (hoses, exhaust hoses, belts, impellors, raw water pump) and had all the fluids and filters changed, plugs done.. She is closed cooled. So, has anyone else seen this, and if so, what might I be looking at here? Thanks, and sorry for the long winded post!

 

[PlayDate]

Boats differ from cars because the water vapor you see at startup in cars is condensation within the exhaust system. On boats......colder water combined with hot exhaust doesn't burn off which is why steam continually is produced. Some exhaust systems produce more steam than others. As an example......both my engines produce steam and have done so for 22 years.

If you are really concerned that this is an anomaly, send an oil sample from both engines into Blackstone. That will at least point you in the right direction and give you a baseline for the future.

If it was a head gasket ......you would be losing engine coolant since you have closed cooling. If there was a problem area ......it would be at the riser or the impeller is not moving enough water. So check your engine strainers.

 

[TFD2001]

Boats differ from cars because the water vapor you see at startup in cars is condensation within the exhaust system. On boats......colder water combined with hot exhaust doesn't burn off which is why steam continually is produced. Some exhaust systems produce more steam than others. As an example......both my engines produce steam and have done so for 22 years.

If you are really concerned that this is an anomaly, send an oil sample from both engines into Blackstone. That will at least point you in the right direction and give you a baseline for the future.

If it was a head gasket ......you would be losing engine coolant since you have closed cooling. If there was a problem area ......it would be at the riser or the impeller is not moving enough water. So check your engine strainers.

Thanks for that reply! I did check the strainers and they were perfectly clean..

 

[Stee6043]

Sounds quite normal to me. The colder the water the more you'll notice the steam. You don't list your location but this is something the folks down south may not regularly experience like us northerners do

 

[copb8tx]

I used to have the same concerns but inevitably it was a result of water temperatures and nothing engine related.

One thing I'd do is check the water around your exhaust outlet when you're anchored with the engines running. See if there's a sheen on the water and try and smell for anti-freeze. Also check your anti-freeze reservoirs and see if there's any fluid loss. If not, you're probably golden.

 

[mrsrobinson]

Sounds like steam to me as well. Send out an oil sample for analysis to Blackstone if you are concerned.

 

[bfernald0]

Agree with all of the above. I'd also check water pressure to see if it's materially higher or lower on that side. Less water raw water flow on one side can cause more steam because the exhaust is hotter.

 

[highslice]

I get that every spring and fall when the weather and water are cool.

 

[sejensen737]

If coolant is leaking into cylinders you will get a "milkshake" look on your oil dipstick. It doesn't take a lot of coolant getting into oil to make it obvious.
As copb8tx said , keep an eye on your clear coolant resevoirs to make sure your coolant level is not decreasing.
If your dipstick oil looks normal , you're probably good...

 

[Tripsdad]

I get the same steam early and late in the season when the water temp is cold. It’s been the same for the 4 years I’ve owned the boat.