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.


In a previous post, we wrote about how InjectorsDirect.com has spent more than $250,000 on state-of-the-art tools and equipment to ensure we’re providing the best diesel injectors for your budget.

What we failed to mention is that we’ve spent thousands more on tools that help make our customers’ lives easier, too.

injector removal tool

For example, see the image at right?

Yeah, that’s a Duramax LBZ fuel injector removal gone horribly wrong (somebody literally has a screw loose on that one).

Want your LBZ injectors installed right?

Fortunately for you, we provide the correct removal tools for the job as FREE LOANERS are offered with the purchase of new injectors. This helps make the job easier, and helps insure that your old injectors are removed without damage.

These tools can all be used & returned with your cores for a full refund, which means it doesn’t cost you anything to use them!

For more information on our removal tools, check out the details on our LB7 Injector Removal Tool, LB7 Injector Sleeve Removal Tool, LLY/LBZ/LMM Injector Removal Tool & 6.0 Injector Harness Connector Removal Tool pages.

Along with providing all of the tools you need to get the job done right, we also back up our injectors with the best warranty in the business.

Each injector comes with all necessary O-rings and copper crush washers necessary for installation. To help you get the most out of your new injectors, we also sell standard, advanced and ultimate install kits for the LB7 engine, and Universal return line kits for LLY, LBZ & LMM engines.

At InjectorsDirect.com, we know what a pain it is when your injectors fail.

That’s why we’re passionate about providing the best quality injectors for your budget, with fast, free shipping, and all the tools necessary to help you get your truck back on the road as soon as possible.

Actual effects of rust and sediment contamination on the valve seat.
Where water and rust can collect.

Following up on a previous blog post about keeping your diesel engine running clean, another way you can keep dirt, rust and debris out of your engine is to make sure your fuel lines are nice and clean.

Over the years, we’ve learned a thing or two about fuel systems, and we have found that when you reuse old, rusted and pitted fuel lines, the chances of premature injector failure skyrockets.

And if you’ve already suffered injector failure and are spending the money to replace a full set, it is smart to replace the high-pressure fuel lines at the same time to prevent corrosion from affecting your new injectors.

LB7 Fuel LineBall Seat ErosionWith a Duramax LB7, for example, an extended length nut on the injector line is actually open to the atmosphere outside of the valve cover.

That means the nut/line interface is exposed to debris and water, which almost always leads to rust.

When the line is removed, the rust is broken loose & can contaminate the fuel system if not replaced.

Fortunately, Duramax LB7 fuel lines are pretty easy to replace,
and we now offer a couple different options to keep your new injectors happy.

Lb7 Fuel Line Cut Apart To Illustrate Rust Buildup
LB7 Fuel Line cut apart to show rust buildup.

As with most of our injectors, we offer LB7 fuel lines as brand new sets (available for $599.99 after a core refund), and we also have more economical refurbished sets (available for $249.99 after core refund).

Our new sets are just that, eight new stainless steel fuel lines from GM.

Our Injectors Direct refurbished sets are a clean yet economical alternative, and are thoroughly cleaned and guaranteed to be rust and corrosion free.

Just one more way Injectors Direct is looking out for your injectors, and doing our best to keep your engine running clean.

Extreme example of rust contamination in an LB7 injector's high pressure inlet
Extreme example of rust contamination in an LB7 injector’s high pressure inlet.
Sealing Surface of a Typical rusted LB7 Fuel Line
Sealing surface of a typical rusted LB7 Fuel Line.
Sealing Surface of a Refurbished LB7 Fuel Line
Sealing surface of a refurbished LB7 Fuel Line.

Want to learn more about keeping your engine clean? Read our previous posts on: