White smoke from an LB7 Duramax engine often indicates faulty injectors.

We’ve heard of rollin’ coal, but rollin’ snow? Not a good sign.

Blowing white smoke is a red flag for your diesel engine, yet we see this happen all the time to our customers.

In many cases, white smoke emanating from the tailpipe (often at idle once the engine reached operating temperature) typically means a worn out injector.

Now this isn’t always the case, but after some trouble shooting we’re usually the go-to shop when diesel drivers need refurbished, rebuilt, or new injectors.


White smoke often occurs when there is either too much fuel being injected into the combustion chamber, or not enough heat to burn the fuel.  Un-burned fuel travels through the exhaust system & exits out the tailpipe which will produce a scent of rich, un-burnt diesel. Other causes of white smoke include lack of compression, or water/coolant entering the combustion chamber.


Black smoke indicates excess fuel is being injected into the combustion chamber and/or not enough air is present.   This can be caused by worn/leaking injectors or restrictions in the air intake system.


Blue smoke is normally the result of engine oil entering & burning inside the combustion chamber.  This is most often caused by low compression, or worn piston rings.

But what we see more often than not are issues related to worn injectors.

Once the problem injector(s) are confirmed (by checking the balance rates and/or capping the feed line to injectors one by one, or bench testing), it’s time to get it fixed.

As we’ve written previously, we test the heck out of injectors with state-of-the-art equipment you won’t find anywhere else. We also stand behind all of our injectors with the best expanded warranty in the business.

When you are shopping for replacement injectors, it’s best to go with a shop that has experience & utilizes the latest testing equipment.

Rest assured, InjectorsDirect.com has all the equipment necessary to clean and accurately test common rail (Duramax and Cummins 2001-present, including piezo) and H.E.U.I. (Ford 7.3 & 6.0) injectors.

You can learn more on our injector testing equipment page, and we’re always happy to provide an accurate assessment of your injector performance, and honest advice on your best repair or replacement options for your budget.

We’ve been doing this since 2009, and have seen just about everything when it comes to failing fuel injectors.

So the last thing we’re going to do is blow smoke.

Contact us for more information, and we’ll get you back on the road again in no time.