3gm30 White Smoke & Max 2000rpm In Forward, Neutral and Reverse Work Normally

[Scubaseas]

Originally Posted by theway

In the morning I’ll bypass the primary Racor filter and see what happens.
If the prop somehow changed, how would one be able to identify that?

Max was 2500-2600rpm depending on how clean the bottom was. Usually cruised at 2200.

Mechanics came and want to take the head off because one cylinder seems a bit noisy. And they think the transmission is a problem.

The primary will stop 30 microns. The engine is usually 5 microns. I'd change both. And purge it. But I'm not going to step on the mechanics toes. Anyone take a compression test?

Water in the cylinder would give a knock, white smoke perhaps reduced power. Depends on where the water is coming from.

The prop should all have the same angle on all blades and freely rotate. It may just need grease. Or nothing if it's an engine issue. Does the white smoke smell like diesel or boiling salt water? Or kind of like apples?

[Scrimshaw4]

Usually white smoke from a diesel is an indication of fuel not being burned completely. While a change in prop loading could be a cause, another more common cause is injector related. Worn injector nozzles will deliver too much fuel which results in white exhaust smoke. If your injectors are over 1,500 hrs. since rebuild / new that might be the problem. JMHO

[Scubaseas]

Originally Posted by Scrimshaw4

Usually white smoke from a diesel is an indication of fuel not being burned completely. While a change in prop loading could be a cause, another more common cause is injector related. Worn injector nozzles will deliver too much fuel which results in white exhaust smoke. If your injectors are over 1,500 hrs. since rebuild / new that might be the problem. JMHO

Highly likely this. IMHO.

[David Mathis]

Usually, smoke color will indicate the issue. Blue indicates excess oil consumption so faulty rings or valve seals would be suspect. Black is usually an indication of excess fuel, possibly due to one or more faulty injectors. White smoke is often from a coolant leak or fresh water getting into the cylinder. A quick check, since the coolant level hasn't decreased, is to shut off the seacock for just a few seconds while the engine is making power to observe any changes in the exhaust color. Don't shut it off for more than a few seconds or the impeller will be damaged unless you have one of the blue run dry type. If the white smoke decreases while the seacock is turned off, you have identified the cause. Now you have to find the leak.

[Snore]

How old is the mixing elbow? A buildup of soot would give all those symptoms.

[Hydro2]

The white exhaust is related to steam in the engine exhaust; steam indicates a water flow restriction in my experience. Check your exhaust elbow and clear the passage for h20 to flow. Experienced this with Yanmar 3GM30F where the exhaust elbow accumulated rust over a period of time and obstructed exhaust water flow. Either chisel out the accumulated rust in exhaust elbow in the water port port side from exhaust manifold, or take off mixing elbow and clean out water ports. White exhaust is evident of exhaust water steam and related to water restriction or flow. just my opinion! Recommend to reference google search for diesel engine exhaust. Frolic
Folic

[NorthCoastJoe]

Your normal max rpm is way low. In my Pearson 30 with a 3GM30F my max rpm is 3600. My prop is matched to this boat, engine, transmission. I run 2800 to 3000 all the time and mix in some time at 3600 every time I am out.
You should be able to get that by adjusting your pitch.

I would look at your exhaust elbow first it may be full of rust and carbon. Yanmar says replace it every 5 years. I have seen the divider plate completely rust out.

The best price I have found is this : https://hdimarine.net/product/gm-sta...-mixing-elbow/

When in doubt rev it out, that engine needs to spin to stay healthy.

[Scubaseas]

Originally Posted by Snore

How old is the mixing elbow? A buildup of soot would give all those symptoms.

Excellent point and spot on advice. See post #14 though. OP says he replaced it.

[sinnerman]

Originally Posted by Scubaseas

Adjust the prop for less pitch. There is a separate adjustment for forward.

You might try servicing the injectors or at least run some LiquiMoly "Diesel Purge" through them. And change the filters. I fill the engine filter with Diesel Purge and let it run at various speeds for 20 minutes.

Second vote for the diesel purge. It is made by Liqui Moly and you can buy it online.https://www.liqui-moly.com/en/diesel-purge-p000038.html

It cleans the the injector pump and injectors, and reduces sticking parts. This may clear up your issue.

Normally you run it from a separate tank, with the injector fuel return line (to tank) going back into the bottle, so it runs in a closed loop. Filling the Racor/fuel filter with it is an alternative.

Good video on a Mercedes Benz diesel showing the crap it is cleaning out of the system:

https://www.youtube.com/watch?v=VfIOHf5UWws

If that does not work, remove the injectors and have them tested in a shop. All three injectors on my engine (Westerbeke/Kubota) were found to have issues with poor spray pattern and/or not closing fully after firing and leaking (dripping) fuel into the engine.

The leaking injectors caused a lot of "pinging or rattling" which is the diesel engine equivalent of "knocking".

I put in new injectors and adjusted the valve clearances ( a maintenance item often overlooked) and it was a different running engine.

The smoke in forward vs reverse probably occurs as there is more loading in forward. The prop is designed to have more thrust in forward than reverse.

On closing, it might be time to consider having the fuel tank cleaned (polished) to clean out water and black crap / algae...

my two cents

cheers.

[Talbot]

My Yanmar manual troubleshoot guide for cause of white smoke is:

Bad fuel

Bad injector

Injection timing off

Excessive burning of Lubricating fluid.

However, I would first look very hard at the exhaust elbow. It is the easiest of these items to pull apart, and has a very probability of being the cause.

[Chayal]

Does the white smoke have a distinct smell?

[skipperpete]

Did the rpm drop and white smoke begin after the shelter bay haul out? Did you open up the maxprop to grease it? I'm still liking the theory that Scubaseas proposed further back in the thread and looking for reasons to support it.

[Shaneesprit]

Originally Posted by Scubaseas

Fixed prop or?

Is the amount of smoke the same when the engine is first started as it as after running it 20 minutes?

White smoke can be engine too cold. too much fuel i.e bad injectors. bad fuel timing. Or warn out rings.

White smoke is normally lack of fuel, black smoke being excess fuel.
White normally seen when there is air in the fuel lines and injection hasn’t completed. Like when a filter is changed or very first start of an engine.
Smoke colour almost White probably a little off white Can be coolant leaks such as head gaskets or cracks.

Change your filters check fuel lines and pumps - change your fuel source, by running the engine out of a can of fuel. Ideally bypassing any lift pump you may have.

How does the engine sound if it is transmission, then you are likely be able to detect excess engine load with your ears. If the engine sounds flat you have no power if it’s fighting then points to transmission.

[sinnerman]

Originally Posted by Talbot

My Yanmar manual troubleshoot guide for cause of white smoke is:

Bad fuel

Bad injector

Injection timing off

Excessive burning of Lubricating fluid.

However, I would first look very hard at the exhaust elbow. It is the easiest of these items to pull apart, and has a very probability of being the cause.

Didn't know that this would cause white smoke, but good point.

Replacing the Yanmar exhaust elbow should be considered a maintenance item. It has an internal sleeve which corrodes away. Sad as it may seem, it is a throwaway part ($$$).

cheers

[theway]

It turns out one injector was adding too much fuel.
And the transmission needed new bearings and a cone drive.