6.6 Duramax Excessive White Smoke

Not all white smoke issues need to send up alarm signals. If you only notice short bursts of thin white smoke in cold weather that dissipates quickly after startup, it may simply be condensation. Keep an eye on it, and unless it persists or gets worse, it is most likely the normal occurrence when starting a diesel engine in winter.

Duramax white smoke emissions may also signal issues related to the following key functions:

Injector Issues

Symptoms of this common issue include white smoke at startup, which worsens over time.

The LB7 trucks have had many injector problems, to the point where GM increased their warranty to seven years/200k miles. What starts as a wisp of white smoke on startup can slowly progress into a larger issue. An injector issue can also manifest itself in the truck “making oil,” meaning the oil level rises over the life of the oil. This symptom is from excess fuel dripping from the injectors, past the piston rings, and into the crankcase.

Even though the redesign of the injectors in 2005 was an improvement, they can still fail and result in the same symptoms. The service manual fix is to replace all eight injectors. 

Before you take the truck to a mechanic, try Diesel Extreme. Treat one full tank (or two tanks, if necessary) to clean out your old injectors.

Fuel Lubrication Deficiency

Diesel engines rely on sufficient lubrication to function effectively. In a high-pressure, common-rail fuel system, the only thing lubricating the internal parts of the injector is the fuel flowing through it. One of the major factors in injector failure is that there is not enough lubrication in the fuel. As a preventive measure, use Hot Shot’s Secret Every Day Diesel Treatment to lubricate and protect the fuel system.

Coolant Leaks

When coolant burns, it produces a distinctive white smoke. The only way for coolant to enter the combustion chamber of an engine is through a mechanical failure. These problems can include a blown head gasket, damaged engine block or cracked cylinder head. Checking the coolant levels is an effective way to confirm whether a coolant leak is the cause.

Poor Fuel Quality or Clogged Filters

Using low-quality fuel can have a devastating effect on every part of an engine. Contaminants can clog up the fuel filters and not burn effectively, resulting in excessive white smoke emissions as unburned fuel passes through the exhaust.

Diesel Extreme is the one-stop solution to tackle many of these issues head-on. It improves the fuel’s cetane rating, making it ignite more efficiently when it enters the combustion chamber. Its safe detergent action attacks sludge and impurities, resulting in a cleaner system.

Try the following preventive measures to keep your Duramax engine performing effectively and avoid future white smoke issues:

• Regularly undertake routine maintenance: Follow recommended schedules for fuel filter replacement and injector inspections.
• Use premium-quality fuel additives: Treat your fuel system regularly with Everyday Diesel Treatment to improve performance and provide ongoing fuel lubrication. White smoke in Duramax engines can often be attributed to injector problems, especially in LB7 models. Diesel Extreme cleans and maintains fuel injector tips, significantly reducing the appearance of white smoke when injector issues are the cause.
• Only use high-quality fuel: Reduce the risk of contamination and ineffective combustion and protect your Duramax engine by always opting for top-quality fuel. Pay special attention when storing fuel to ensure containers are rust- and moisture-free.