White Puffs of Smoke

[jharwood@fulcrumstrategy]

I went up to my boat this weekend and the Atomic 4 engine started puffing a lot of white smoke. It's been running fine with no smoke coming out of the exhaust.

I asked someone on the dock about it and he said that this may mean my engine seals are shot. Can you tell me if this is the case or could it be a more minor problem?

Thanks,
James

[Don Moyer]

James,

The Atomic 4 has no seals that have any likelihood of causing which smoke in the exhaust.

It's important to clarify the difference between steam and white smoke. White smoke will linger behind the boat for several boat lengths, while steam will dissipate quickly - normally within 5 to 10 feet. White smoke is almost always caused by defective oil rings which allow oil to enter the combustion chambers and burn along with the fuel mixture. Unless an oil ring has broken, oil smoke usually develops over time, rather than to appear all of a sudden.

Steam can appear rather suddenly and will normally be caused by one of the following conditions:

1) In the cool part of the season, it's rather common within our northern operation locations for people to report a "vapor" coming out with the exhaust on their boats. This vapor is simply a matter of warm moist air cooling and condensing behind the boat. The problem goes away as soon as the weather warms up a bit.

2) Early model cooling systems will create a small amount of steam until the engine gets fully warmed up. While an early model engine is still cool, most of the cooling water is being recirculated, leaving an insufficient amount of engine cooling water to be discharged into the exhaust system to cool the hot section. What water does enter the exhaust system turns to steam. As soon as the engine warms up, more water will be discharged to cool the exhaust system, and the steam should dissipate.

3) In both early and late model engines, cooling water flow may have reduced, due to a defective water pump or a restriction in one of the cooling hoses, so that there is no longer sufficient water flowing through the engine to keep the hot section of the exhaust system cool, and a small amount of steam may be developing in the part of the hot section where the engine cooling water enters the system.

4) Steam will sometimes be created as the hot section slowly clogs with precipate where the engine cooling water enters the hot section, usually just above the inlet to the water lift muffler.

NOTE: In both (2) and (3) above, the creation of steam may be somewhat exacerbated if the hot section was recently wrapped with an insulating material, since the insulating material will result in a hotter temperature
within the hot section.

5) The most serious scenario would be steam caused by a small amount of water leaking into the exhaust manifold through a crack in the block, head or manifold itself. Steam created by a small crack in one of these cooling water jackets, will usually elevate exhaust back pressure within the manifold or the rest of the exhaust system, which will - in turn - cause a very thick caramelized brown goo to form on the stems of intake valves. We have several cases on record wherein intake valves have stuck open in only 5 to 10 hours of operation.

Best regards,

Don Moyer

[jharwood@fulcrumstrategy]

Don. Thanks so much for the quick reply. I forgot to mention that the white puffs don't appear until the engine has been running for a while so I'm thinking that one of the explanations you provided for steam formation might be the most plausible.

I haven't replaced the impeller in a couple of years so I'm wondering if that might be contributing.

James