white smoke above 2000 rpm

[rlg]

I have a westerbeke 46, 5300 hrs. It runs great and has since Ive had it with 1300 hrs.
Now she smokes white above 2000 rpm, only after fully warmed up.
If I keep revs lower, she'll smoke less, to nothing at 1200 or so.

Ive recently had the exhaust manifold off to replace the exhaust elbow, Im thinking this must be related but don't know exactly how.

Ive pressure tested the fresh water cooling system, no leaking.
Never has overheated but will always take a small amt of coolant whenever I check it.
Could there be a crack in the exhaust manifold?
Otherwise she runs great, hardly burns any oil....

Whats the right order to approach this? Im obviously hoping its not cracked head, cylinder, or head gasket.

Any ideas, suggestions, are welcome and appreciated

thanks, Rob

[Fiveslide]

Is the engine turbo charged? White smoke could be unburnt fuel from a failing injector also.

[rlg]

Also I had the oil analysed and it came back ok. some metals but nothing alarming.

[rlg]

not a turbo

[scoobert]

normal. most diesel marine engines smoke a bit of white.
now if your leaving a long trail.... then your burning water.

[colemj]

Rebuild the injectors.

Mark

[djmarchand]

Does the white smoke dissipate ten feet behind the exhaust and does it only do it in some temperature/humidity conditions. If so it is normal or possibly a low raw water flow condition that is causing steaming at higher loads and rpms. Check the raw water intake, strainer, impeller, heat exchanger, injection elbow for restrictions.

If the white smoke trails and doesn't dissipate then it is likely injectors. Have them tested and if necessary rebuilt.

David

[rlg]

The smoke does dissipate after a few feet. It is not diesel...no smell really.
It does seem worse sometimes than others but is definitely not normal.
The engine starts and runs perfectly, a little smoke at startup, then nothing.
It seems to coincide with the thermostat being open, but never overheats.

If I run low rpm, 2000, for a long while, I get the beginnings of it, very lite, barely noticeable. With more rpm it gets heavier...

Is there any way it could be raw water steam?

What steps should I take..

Thanks very much for the input

[westwinds]

If strong smell of diesel, then probably bad injector. Most likely it is insufficient cooling because the problem occurs only after warm up and at higher power settings. Check your raw water intake on exterior of hull, the raw water screen, the raw water impeller, the heat exchanger, collapsed hoses, belts, even the thermostat if stuck open just a little. What does the temperature gauge show at lower and higher power settings?

[capttman]

Caveat "usually" white smoke is caused by water in the fuel system. If u are losing coolant slowly I would first suggest a head gasket.
You say it started after you replaced the exhaust manifold? Was there any coolant in any of the ports?

[Cheechako]

Originally Posted by capttman

Caveat "usually" white smoke is caused by water in the fuel system. If u are losing coolant slowly I would first suggest a head gasket.
You say it started after you replaced the exhaust manifold? Was there any coolant in any of the ports?

Yeah, I'm thinking a minor leak in a head gasket. The coolant is going somewhere.
However, It could just be going out the cap vent into the bilge when pressure builds up. My 4-108 did that so took a cup of coolant every now and then. I finally figured out it was the cap vent.
Too bad diesels are so hard to do compression tests on. Sometimes seems faster to just pull the head!

[motion30]

I had the same.thing on cat. Rebuilt injectors fixed it

[djmarchand]

The man said that the white smoke dissipates a few feet behind the engine and it doesn't smell like diesel. That almost certainly suggests that the raw water is too hot and is "making steam". The raw water is hot because the flow is low.

If you were losing a lot of coolant then it might be coolant losss particularly if it smells like antifreeze, ie a head gasket. But this doesn't seem to be the case.

As I said before, check the raw water intake slots, the raw water strainer, the impeller, the heat exchanger, and the injection elbow. One or more could be plugged or worn and causing low raw water flow.

David

[rlg]

thanks for all the replies!

djmarchand, I will check the raw water intake and strainer but there seems to be the usual amount of water with exhaust, not excessively hot...
The temp gauge does not fluctuate once engine warms up.

Im not losing a lot of coolant, ran the motor for 40 hrs over a week from florida to NY without overheating or adding coolant, just some smoke, never used a lot of rpm..Never has the engine taken more than a cup or so of coolant.

when I fill with coolant, some does leak out cap after engine is warm, then it stops. I may not be losing any coolant.

From my experience, the last thing I worked on is usually the problem. I just cant figure how the exhaust maniflold/coolant "tank" is causing the problem, maybe its not

[rlg]

BTW heat exchanger is only a couple of years old, injection elbow is new.