Steamy exhaust & sea water temperatures

Twister_Ken

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The advice of the panel is sought...

Yanmar 3YM20. In UK waters the exhaust has always been non-steamy. Now, further south, it steams.

UK seawater temps in summer - about 15-17º?. In current location about 21º. Both measured with the on-board transducer, so even if not accurate the relationship between them will be the same.

Would you expect an increase of, say, 5º and the consequent reduction in cooling potential to be the cause of steam, or would you suspect another cause?

Some of today will be spent examining the impeller and pipe work on the raw water side and making sure there are no obstructions, salt build-ups etc, but if that proves non-conclusive should I look further, at the heat exchanger, say?

Thanks for any suggestions, opinions, donations, etc. And no doubt, obfuscations too!
 

Halo

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Mine steams but the water coming out is not hot. I suspect it's not steam as such. Perhaps it is generated in the mixing elbow and does not have time to condense before coming out of the exhaust. A few degrees could mean that a spot in the mixing elbow gets hot enough to raise steam. Only other thing I can think of is that your impeller is softer in the warm and not delivering as much water.
 

MM5AHO

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Steam isn't only related to temperature.
Your breath comes out at about the same temp, but some days its "steams" and other days not. Air temp, and humidity will have an effect.
So the difference between your exhaust water and air temp and humidity are probably doing this. At higher water temps (and air temp) then your exhaust exit water will be hotter ( assuming a pretty standard rise over the engine cooling system), but in hotter climes the humidity will likely be higher.
 

DickB

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My Perkins M90 steamed out of the exhaust. The oil had water in it and was emulsified!!! I ended up taking the head off suspecting a blown gasket. It was fine however in stripping the engine down I found that the oil cooler was leaking water in through a corroded seal and failed "O" ring. Once that was fixed everything seems ok...

cheers,
 

rogerthebodger

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I have a similar issue where I am with a sea temperature around 22 deg C all year. Investigated all other causes but not found anything wrong so would also be interested in any comments.
 

RichardS

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As others have said, "steam" is a bit misleading. Driving an air-conditioned car in a hot and humid African country meant that sometimes the "steam" pouring in through the air vents made it difficult to see the road ahead!

If the engine coolant level is not going down and the sea water exiting the exhaust is only slightly warm I doubt whether there is anything to worry about.

Richard
 

Twister_Ken

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FWIW I checked through the raw water side as far as the exit from the pump this morning. Impeller appeared OK though maybe over-enthusiastically greased when the last service was done, so removed a few blobs from the impeller blades.

Taking off all the pipework to that point dislodged some scale/salt, but not copious amounts. Freshwater system absolutely full and header tank exactly on the line.

Conclusion (yet to be tested) - a few minor obstructions were slightly slowing down the flow of slightly warmer than usual seawater, resulting in steam where there had been none.

Fingers x'd.

TK
 

geem

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FWIW I checked through the raw water side as far as the exit from the pump this morning. Impeller appeared OK though maybe over-enthusiastically greased when the last service was done, so removed a few blobs from the impeller blades.

Taking off all the pipework to that point dislodged some scale/salt, but not copious amounts. Freshwater system absolutely full and header tank exactly on the line.

Conclusion (yet to be tested) - a few minor obstructions were slightly slowing down the flow of slightly warmer than usual seawater, resulting in steam where there had been none.

Fingers x'd.

TK

Check the injection point at the exhaust elbow. There could be a build up of carbon reducing the raw water flow rate a tad. We have been in water upto 29.5 degC ( measured on calibrated thermometer) all winter in Caribbean. We don't get steam ever but the generator runs very warm as the air temperature is even higher
 
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