White smoke in my exhaust?

White smoke is usually burning oil.
Worth getting a diesel man to look at it.
Are you sure it's not steam and your raw water impeller/system needs some attention?
 
Could be steam.

Otherwise probably un-burned fuel, however you usually get over-fuelling smoke at startup and low revs.

Just keep a check on oil levels, and check that there's plenty of water coming out of the exhaust.
 
I thought I was told that White smoke at startup could be unburnt diesel but once warmed up it would be steam, Black smoke = overfuelling due to overload etc, and Blue smoke was oil burning, but I stand to be corrected.
 
Leighb said:
I thought I was told that White smoke at startup could be unburnt diesel but once warmed up it would be steam, Black smoke = overfuelling due to overload etc, and Blue smoke was oil burning, but I stand to be corrected.
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No need for correction, that is also my understanding. Steam is sometimes created if the flow of cooling water is reduced, typically by salts partially blocking the exhaust elbow. This is not often a problem on the 3GM30 but is easy to check.
 
Could easily be steam. There is no issue up to 2000 revs, then it shows.
Only other thing i have changed is I added a bit of coolant to the expansion tank before leaving, to bring it up to halfway.
What and where is an exhaust elbow please and how do i check it?
 
The exhaust elbow is at the back of the heat exchanger and connects to the rubber exhaust hose. It will also have a pipe in it which is the injection point for the cooling water to mix with the exhaust gases. The inside of the elbow can get partially blocked with salt water and carbon/oil deposits. To check you need to remove it and inspect the inside.

However, not sure it is an issue. If you are getting plenty of cooling water through and not using oil, then suggest you give the engine a long hard run at say 3000rpm with bursts up to maximum of around 3600. These engines do not like continuous low rpm running, they are designed to work in the range of 2000-3600 and your normal cruising speed should be around 2500.
 
Tranona said:
The exhaust elbow is at the back of the heat exchanger and connects to the rubber exhaust hose. It will also have a pipe in it which is the injection point for the cooling water to mix with the exhaust gases. The inside of the elbow can get partially blocked with salt water and carbon/oil deposits. To check you need to remove it and inspect the inside.
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A quicker (and cheaper, as you will not need to change the gasket) method if you have space is simply to remove the exhaust hose from the elbow and look inside, using a mirror if necessary. The elbow is made up of two concentric tubes, gases down the middle, water down the outside. If it is blocked it will be obvious. Also remove the 1/2 inch hose carrying water to the elbow and check that the spigot on the elbow is clear.
 
Check the engine temperature gauge if its normal ok but if it is higher than usual then you are not getting enough
engine cooling water through maybe something blocking the raw water intake valve, OR are you loosing coolant from
your header tank? this could mean an engine gasket problem also check that you engine oil is clear NOT milky.

My best guess is you have a blockage maybe a small plastic bag blocking the intake,
 
Does the 3GM use a similar style of exhaust elbow to the 1GM ie. One tube welded within another? If it does and you are getting plenty of water out of the exhaust (if the exhaust is above the water you can compare the volume with that specified in the manual using a bucket) my money is that the weld between the two has failed due to corrosion and is allowing salt water into the head hence the steam. If its only a small hole at this stage you'll probably only notice at higher rpm when the pump really gets going.

Apologies if this is a red herring as i am not familiar with this model but this was what i discovered with a mates 1GM that had similar symptoms. It was only when i took the elbow off and filled the outer jacket with water while placing my finger over the water inlet that i discovered a pinhole in the weld
 
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Looks like it does use a similar elbow having just checked. Its a stupid bit of design compared withe the one piece betas etc but if you do need to replace it i suggest these guys. The one i sourced for the 1GM was better made and way cheaper than the Yanmar part
www.exhaustelbow.com
 
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If the rubber exhaust pipe, just after the water injection elbow, is getting hot to touch with the rpm over 2000 and steam in the exhaust, the raw water system is not passing enough water. That could be a partially broken impeller, a blockage in the waterways or even an air leak into the system, like around the sea water inlet filter.

Since I fitted an exhaust temperature gauge to my Yanmar 4JH4E i discovered its exhaust gets hottest at tick over in gear. At higher revs the exhaust goes down near to sea water temperature as so much water is pumped through.
 
steve yates said:
Thx everyone. Had very limited power and wifi access for tablet, but next morning I checked the seawater filters and removed a little bit of weed, since then it seems to have been fine.
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Jolly good. Nice to hear that it was something simple (these things usually are).
 
Glad you got this one figured....but just for anyone reading this in the future...white smoke is certainly not indicating burning oil.
All the best
 
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