White Smoke in Exhaust - What next?

[lawrence_craig]

Hi all,

TLR - Seeing white smoke from exhaust, coolant temps ok, how long is it ok to wait? How urgent is it? Till it becomes an issue?

I have a Volvo Penta D2-55

I am sure this has come up a lot in terms of what causes it. I believe it has to do with overheating of exhaust fumes, meaning it's likely to be an issue with the exhaust cooling system.

I have checked coolant levels and they are ok. Coolant runs at about 87-88C whilst in summer Greek waters. Higher than I'd like as normally sits around 84/85 bu unsure how much that is due to higher water temps during summer (26C).

I suspect it's the exhaust elbow that hasn't been removed & cleaned since 2019 and has been through 750-1000 hours of motoring.

If the coolant temperatures are ok, and remain ok, how urgently do I need to deal with this?

[lawrence_craig]

Couple of edits and clarifications on the above as can’t edit the post directly:

I realise that it might be other reasons. The smoke volume isn’t significant, it’s just noticeable when looking at the exhaust when sailing under motor, it disappears shortly after forming. I’ve checked the saildrive inlets and it seems clear as well as the intake strainer. I have thought about removing the exhaust elbow but not near any where I can get some replacement gaskets or other parts if needed. water pump">Raw water pump impeller is ok and not leaking.

[GordMay]

If the smoke is just a puff, at start, there is probably not much to worry about. Especially, if it has been sitting [cold start], it could just be built-up condensation.

If it lasts a few minutes, after the engine is started, and there is a rich diesel smell, they may be some cause for concern. Some of the likely causes include:
Faulty injectors – stuck open, faulty timing.*
Fouling deposits - Worn piston rings, or cylinder glazing.
Plugged crankcase breather.
Air in the fuel system [loose fittings].
If equipped with glow plugs, could be faulty plugs or module.

* Loosen the fuel line nut one half turn. If the engine operating sound changes, and its speed slows down, then that injector is firing. If there is no operating change, then that injector is faulty.

[Fuss]

Originally Posted by lawrence_craig

Couple of edits and clarifications on the above as can’t edit the post directly:

I realise that it might be other reasons. The smoke volume isn’t significant, it’s just noticeable when looking at the exhaust when sailing under motor, it disappears shortly after forming. I’ve checked the saildrive inlets and it seems clear as well as the intake strainer. I have thought about removing the exhaust elbow but not near any where I can get some replacement gaskets or other parts if needed. Raw water pump impeller is ok and not leaking.

I think the heat exchanger is not cooling enough and so probably needs cleaning or sea water impellor or slightly blocked through hull.

[Avionics_Joe]

You are getting enough water to cool the engine but not enough to cool the exhaust. If your impeller is good you have a blockage somewhere.

[gonesail]

probably steam. if it was a yanmar I would say check the exhaust elbow.

[rslifkin]

Steam may or may not indicate a problem. Just about every wet exhaust will show a bit of steam under the right combination of seawater temp, air temp, humidity, and engine load. Some steam more than others. If you're seeing an increase in steam under operating conditions you're used to seeing, then it may indicate a problem. But if the weather is unusually cool and damp, for example, it would be common to see more steam than in warm, dry weather.

It certainly wouldn't hurt to check out the exhaust elbow and make sure water flow isn't restricted and that the water is being distributed well (if it's not, you may risk burning up an exhaust hose).

[Greg Brannon]

When my Westerbeke genny began emitting whiter exhaust, I followed Nigel Calder's advice to narrow the likely reason to steam, but I wasn't sure of the root cause. The genny was used lightly, so I monitored it, but the genny eventually shut down due to high exhaust temp. Since I'd recently changed the raw water pump, including the impeller, I inspected the heat exchanger and found that many of the tubes were blocked. My underway repair was to clear the tubes with a coat hanger and fresh water flush which allowed the generator to be run many more times before I realized the heat exchanger needed replacing due to cracks in the casing.

Don't know if this is your problem, but it gives you a place to look.

Good luck!

Greg.

[deblen]

White "smoke" : If it rises quickly & dissipates,it is steam.
If it stays low,close to water & causes a sheen on water,it

is raw fuel.
Black smoke: Usually caused by excess load on engine and/or excess

Throttle.
Put your hand in smoke-does it smell like raw diesel & is it "squeaky" when fingers rubbed together-or is it just watery?
Cheers/Len

[Uplander]

Check the bearings in the waterpump.

[lawrence_craig]

Thanks all, great advice. I appreciate you all.

I'll have a look into the above and start narrowing things down.

[AKA-None]

Originally Posted by Greg Brannon

When my Westerbeke genny began emitting whiter exhaust, I followed Nigel Calder's advice to narrow the likely reason to steam, but I wasn't sure of the root cause. The genny was used lightly, so I monitored it, but the genny eventually shut down due to high exhaust temp. Since I'd recently changed the raw water pump, including the impeller, I inspected the heat exchanger and found that many of the tubes were blocked. My underway repair was to clear the tubes with a coat hanger and fresh water flush which allowed the generator to be run many more times before I realized the heat exchanger needed replacing due to cracks in the casing.



Don't know if this is your problem, but it gives you a place to look.



Good luck!



Greg.

Careful with poking anything in your heat exchanger
If, if the tubes are thin you could poke a hole in the tube
Likely maybe not, possible maybe so

[sinnerman]

White smoke in the exhaust (on a diesel) is often indicative (believe it or not) of a defective fuel injector.

Fuel injectors (and valve clearance adjustments) are two maintenance items often overlooked.

The injectors need to be periodically (every two years..?) removed and tested for proper spray pattern, proper adjustment of the opening pressure and that they do not drip (leak) after firing.

With the injectors removed is the perfect time to check/readjust the valve clearances as it is easy to mechanically rotate the engine without compression building up in the cylinders.

When I checked the injectors on my engine, all three had some sort of problem. Leaking, poor spray pattern (actually "squirting fuel) and wrong set pressures.

After replacing the injectors and adjusting the valves, the engine ran noticeably much smoother, started easier and had more power.

My two cents

cheers.

[SOLAR SUPPORT]

Rusting problem of VP elbows made of cast iron is very common. Sea water starts to deteriorate this part in a very short time, increasing blockages after rusting in elbow pipe sections where sea water and exhaust gas mix cause serious problems. Dense white smoke from the exhaust is a sign of this problem. The worst-case scenario is that the aluminum exhaust manifold is punctured by corrosion from back-splash salt water and fresh coolant flows into the engine crankcase. I recommend that you replace your exhaust elbow with a stainless one as soon as possible.

[rgleason]

I have read this thread, but my experience says this problem is due to not enoughr raw water flow due to bad impellor, broken impellor parts blocking, filter blockage, or seaweed growth on the grill. Or blockage in the heat exchanger or hose.