Has anyone experienced this on their engine? The engine is 18 years old and the meter shows 1100 hours. It starts first time, doesn't blow smoke when it's tied up to the marina and run at full power. I've only noticed it after motoring along at about 2000rpm for a while. I've only owned the boat a few months, so I don't really know how long it's been doing this.
Yanmar 3GM white smoke
- Thread starter Brucegra
- Start date
What happens when you operate at higher rpm? When was the mixing elbow last replaced? Are you getting sufficient water coming out of the exhaust, if not you may have a clogged mixing elbow? Have you checked coolant level? Lots of potential causes like a fouled mixing elbow indicating a need for replacement and others identified in this article: The 3 Causes of White Smoke From A Diesel And What To Do Next - Learn Diesels
Same question came up on this thread with lots of potential causes identified: White smoke in exhaust-Yanmar diesel | Sailboat Owners Forums
Same question came up on this thread with lots of potential causes identified: White smoke in exhaust-Yanmar diesel | Sailboat Owners Forums
Last edited:
Thanks for the replies. I did wonder if it was steam. It dissipates very quickly behind the boat. The engine is also running at about 175-180 degrees, which seems hot, but I'm not sure what the normal range is. It is discharging water through the exhaust, but I'm not sure it's enough. The coolant level is fine and doesn't change.
Brucegra..........thanks for the update. Unless you have records when the last engine service was performed suggest doing one.........particularily oil/fuel filters, engine oil and raw water impeller replacement and heat exchanger, drive train and exhaust elbow inspections. That is what I do on every boat I purchase. No service history on my Hunter 46 so has a complete engine service (500 hours). On the otherhand, a recent powerboat purchase I obtained the engine service records (2000 hours) from the diesel mechanic and they were last serviced 50 hours prior to purchase so good for 200 hours.
Last edited:
I also suspect the mixing elbow is causing the white smoke. Restricted flow of water into the exhaust elbow could raise the temperature of the elbow to the point that the water will be vaporized and exit the exhaust as steam. Also, the restriction will most likely cause the engine temperature to rise because of the reduced water flow through the heat exchanger.
Take the small hose off the top of the elbow and check for a restriction. If nothing is obvious there, you may need to remove the elbow for inspection.
Take the small hose off the top of the elbow and check for a restriction. If nothing is obvious there, you may need to remove the elbow for inspection.
175-180 is typical for diesel inboards and is not, by itself, a steam generating temperature. Yes, a restriction seems probable. If you take a rag and carefully capture some water from the exhaust (to avoid getting a burn, not with bare hands) is that exhaust water really hot? What kind of water quantity coming out?
Title says 3GM, not 3GM(F), so I presume it’s raw water cooled? Assuming that’s the case 175-180 does sound warmer than normal for raw water cooled engines. I agree with the others that it sounds like a cooling water restriction. In fact Nigel Calder’s book says “White smoke at high engine speeds and loads is almost certainly water vapor, most likely caused by reduced cooling water flows—check the raw-water system.” Also keep in mind that when looking at troubleshooting guides for land based engines they generally won’t consider any raw water cooling, so problems like that will be overlooked there.
I have a 2GM20F, and one day I checked the exhaust water temp…was surprised to find the water pretty tepid…lake water was probably in the 60’s, but really surprised the water was barely warm.
Greg
It is a 3GMF. I contacted a Yanmar dealer and they told me that when the thermostat is fully open, the temp should be around 185, so it doesn’t seem too hot. Thanks for all the suggestions. I’ll test them out in the next week or two and post an update when I work something out.
I had same be problems of white smoke with my Westerbeke B30 comes on after 20 mins. see feeds...Old Smoky...got v good dedicated advice in this blog.
changed all fuel filter etc and fuel. now only black smoke when do I'll throttle.
changed all fuel filter etc and fuel. now only black smoke when do I'll throttle.
I've checked out as much as I can and can't find anything mechanically wrong yet, but I've noticed that every time the steam has appeared, the humidity is around 90-100%. When it's around 30-40%, it all looks normal. The water temperature is about 50 degrees here right now, so does anyone know if it's possible this isn't really a problem after all, just hot exhaust being cooled by cold water on a humid day? Is this not even steam? This is a 3GM30F by the way. I didn't put the full details in the first post.
It can be just that.
A bit complicated to explain.
First read...
Dew point - Wikipedia
But this is the best link for Water Vapor in the air.
Psychrometrics - Wikipedia
_____
Good observation...
Jim...