White exhaust water

Happy 2019 Everyone!

I started up my genset yesterday for the first time in months. The exhaust water was clear (as it should be I think). So I started the engine up and the exhaust water was white. It clears up after 10 minutes or so, but never as clear as the genset. What do you think?

Dave

Pics?

Alaskan Sea-Duction said:

Pics?

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Didn’t take any. Looks like diluted milk which gradually clears up over 10 minutes or so.

The first thing to check is if your coolant is getting low as it may be a leak in your heat exchanger or elsewhere putting antifreeze into your raw water discharge.

Forgot to mention the exhaust is light blue until the engine is nice and warm and no appreciable sheen on the water.

Blue smoke in a diesel can mean air in the fuel system, I don't know if that would affect water color. It may be two separate issues, have you changed your fuel filters lately and perhaps introduced air? I'd still check coolant level and consider bleeding the fuel system. You could taste the discharge water at start up to see if it's sweet which indicates ethyl glycol or antifreeze, don't swallow (in truth I don't want to recommend tasting as it's toxic).

I've taken apart a fair number of bits and pieces of my cooling system this winter and found signs of white corrosion buildup in them. Wondering if you are seeing signs of corrosion in your raw water system that flushed out on your first startup. I'm not sure there could be enough "stuff" to flush for 10 minutes though.

I'd check the pencil zinc and condition of the heat exchanger and oil coolers.
I would also be concerned about one of the two oil coolers failing. Check engine for oil loss and transmission oil for seawater intrusion.

Oil in the raw water discharge would be evident on the surface as it would be unburned. Zincs degrade from the minute they're put in service so there would be no apparent change in the discharge water. The white stuff in a seawater circuit is salt, calcium and other minerals which if for some reason such as overheating started to be released in larger quantities may be in evidence in the discharge but as you said probably not after ten minutes. Of course it's difficult to diagnose from afar, it may be as simple as the water that's being drawn into the system from the seacock.

I'd be concerned about something corroding in the sea water circuit.

How would that manifest itself in discharge water? Like zincs, something is always corroding in the seawater circuit, usually exposing itself with a leak. A good flush, inspection and new zincs certainly wouldn't hurt anything though.

If the raw water system is sucking in air somewhere before it goes overboard, that will cause small air bubbles to form and give the appearance of white water or less than clear look to the water. I would give the genset and it's cooling system a good going over.

ben2go said:

If the raw water system is sucking in air somewhere before it goes overboard, that will cause small air bubbles to form and give the appearance of white water or less than clear look to the water. I would give the genset and it's cooling system a good going over.

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My though too.


Is this something new, or could you just be noticing it now?


If new, check strainers fro good seal, and check you impeller. I expect a damaged blade on the impeller could cause cavitation and air in the exhaust water.

That would be indicated by a leak somewhere on the suction side of the pump although I doubt that there would be enough air entrained after the water exits the pump, goes through whatever coolers may be in line, has exhaust and more air injected at the mixing elbow and then travels down whatever there is for exhaust hose, mufflers etc. to be noticeable.

Catch a sample of the exhaust water in a glass just after starting and it is white. Then let it settle and see if it is just air, oil, fuel or something that settles out. If that isn't easy to do (maybe the exhaust exits underwater) then disconnect the hose to the injection elbow and catch a sample of that. The exhaust hose will be fine for a minute or two with no water flow if the engine is started from cold.



David

Dave, Happy 2019. Blue on startup is normal on a cold Lehman. Mine does the same and it goes away completely when it is warmed up. I also have a bit of the cloudy water on startup and when running. It’s done that for the four years I’ve owned it and there is no water in the oil, coolant leak, or anything else. Check your things as others have suggested but it doesn’t sound crazy to me. Sometimes things can be over complicated. I ran mine yesterday and filled up fuel and did a 2500 RPM run out through the channel and then back to the marina. Was fun actually spinning the prop as it’s been awhile.

Email to me from a marine diesel expert....

"take a sample. It is just aerated water. It happens when the exhaust shows up before the water flow and the piddly amount of water at the beginning of flow gets aerated.

Air in fuel or corrosion ......(probably not)"