Maximizing Duramax Lbz Performance: Fuel Injector Change Intervals

The LB7 engine is a popular diesel engine used in Chevy and GMC trucks. While the LB7 engine is generally reliable, one common issue that owners may encounter is the need to replace the fuel injectors. This process can be complicated and time-consuming, requiring a range of tools and parts, and it is recommended that truck owners drain the engine coolant before starting. While some experienced individuals may choose to replace the injectors themselves, others may prefer to take their truck to a dealer or mechanic for this service. The time it takes to replace injectors can vary depending on the experience of the mechanic and the availability of parts, but it generally takes between 4 and 40 hours. Replacing fuel injectors can be an expensive endeavour, with the cost of a full set of new injectors ranging from $3,000 to $5,500.

LBZ injector replacement tools and parts

When it comes to LBZ injector replacement, there are a variety of tools and parts that you will need to get the job done. Here is a detailed list of the tools and parts required for a successful injector replacement:

Tools:

• 5mm allen bit, wrench, and ball end bit
• 8mm allen bit or ball end bit
• Torque wrench
• Basic set of metric tools
• 19mm wrench, stubby, crows foot
• Pick set
• Pry bar set and maybe a floor jack
• Schley Tools – 13300 GM Duramax 6.6L-V8 LLY, LBZ and LMM Injector Puller Kit (optional)

Parts:

• 8 LBZ fuel injectors
• Install Kit:
• 8 Joined banjo washer pairs for connecting return lines to each injector
• 2 Joined banjo washers for connecting the return line on each side to the head
• 16 External injector O-rings
• 8 Copper seat washers
• 2 tubes of "Permatex Ultra Grey" RTV silicone sealant
• O-rings, copper crush washers, return line seals, and lower valve cover gaskets
• High-pressure fuel lines (optional but recommended)
• LLY/LBZ/LMM return line kit (optional but recommended)

It is important to note that injector replacement can be a complicated process, and it is always recommended to consult a professional or a repair manual for detailed instructions on how to perform the replacement safely and correctly.

How to identify a bad injector

The LBZ Duramax injectors are crucial components of the 6.6L Duramax engine, delivering fuel to the combustion chamber. Over time, these injectors can develop issues that affect engine performance. Here are some ways to identify a bad injector:

• One of the most common signs of a bad injector is a rough idle or frequent misfires. You may notice the engine shaking or vibrating more than usual, especially when idling.
• Bad injectors can lead to a noticeable reduction in engine performance, such as sluggish acceleration, reduced power output, or a lack of responsiveness when pressing the accelerator pedal.
• If you observe thick, black smoke coming from the exhaust, it could be an indication of faulty injectors. The excess fuel that is not properly atomized by the injectors can result in unburned fuel being expelled as smoke.
• Malfunctioning injectors may cause the engine to consume more fuel than usual, leading to more frequent refuelling.
• Damaged injectors can result in engine knocking or ticking noises, especially under load or during acceleration. These sounds may indicate that fuel is not being properly delivered and burned in the combustion chamber.
• When injectors start to fail, the vehicle's onboard computer (ECU) may detect the issue and trigger the check engine light. An OBD-II scanner can be used to retrieve any injector-related fault codes, such as P0201 to P0212 (injector circuit malfunction).
• Faulty injectors can cause issues with starting the engine, such as extended cranking before the engine starts. Additionally, the engine may stall or shut off unexpectedly while driving, particularly at low speeds or idle.
• If you notice a strong smell of fuel inside or outside the vehicle, it could be an indication of leaking injectors.
• When injectors are failing, you may experience a loss of engine power when towing or carrying heavy loads. The engine may struggle to maintain speed or climb hills.

Injector removal and installation

Passenger Side:

• Remove the passenger-side wheel and inside fender (black plastic).
• Drain the coolant from the radiator by removing the drain plug on the bottom passenger side.
• Disconnect the big blue turbo intake hose from the intercooler by loosening the 10mm nut on the clamp and pulling the hose off.
• Unhook the turbo intake hose off the top of the engine and wiggle it off.
• Remove all the tubing, intake, the fuel filter bracket (3 bolts holding it on and a 4th one just holding a coolant line to it) and the Fuel Injector Control Module (FICM). Disconnect the FICM by sliding the tabs up and down.
• Disconnect the glow plug wire and move it out of the way.
• Remove the keepers on the high-pressure fuel lines with an 8mm socket or Phillips-head screwdriver.
• Remove the injector lines with a 19mm wrench.
• Remove the upper valve cover. Use the tabs sticking out as pry points.
• Remove the lower valve cover. Disconnect and remove the injector wire harness. It is held down to two injectors with four 7mm nuts and two gold 10mm bolts.
• Remove the injector return line. Be careful as these bolts strip easily.
• All the injectors have a bracket holding them in place. Unscrew them with an 8mm Allen bit.
• To remove the injectors, twist them side to side while pulling up. Make sure to remove the copper washer from the bottom of the cup.
• If the injector comes out with the cup, the coolant from the head will drain into the cylinder if the coolant was not drained first.
• Clean out the hole and use a small amount of lube on the O-ring of the new injector.
• Reinstall a new copper washer at the bottom of the injector cup.
• Install the injector and torque it down to 37 ft-lbs.
• Reinstall the return lines with new seals. Tighten the banjo bolts to 12 Nm or 106 lb-in. Tighten the 12mm banjo bolt that goes into the head to 11 lb-ft.
• Install the lower valve cover and tighten the bolts in sequence to 10 Nm or 89 lb-in twice.
• Install the injector harness and tighten the bracket bolts to 9 Nm or 80 lb-in. Tighten the 7mm connectors to 2 Nm or 18 lb-in.
• Put a bead of sealant on the bottom of the upper valve cover about 2-3mm wide and 1mm high. Install the upper valve cover and tighten the bolts to 8 Nm or 71 lb-in in sequence.
• Install the injector lines and keepers.

Driver Side:

• Remove the inner cooler tube.
• Remove the upper radiator rubber hose.
• Remove the metal radiator crossover tube by taking out the 2 x 12mm bolts from the valve cover and the 12mm bolt from the thermostat housing.
• Unbolt the A/C pump (4 bolts) and slide it forward slightly.
• Unhook the main wiring/engine harness bail connectors by squeezing the 2 tabs and lifting the grey handle.
• Remove the 3 x 12mm bolts that hold the large bale bracket to the driver-side upper cover.
• Disconnect the fuel lines where they go over the valve cover by the driver's firewall. First, remove the spring clips, then the lines themselves.
• Remove the high-pressure lines (clips first).
• From this point, the driver side is just like the passenger side.

Additional Notes:

• Before starting, drain the engine coolant in case an injector cup comes out with the injector.
• When reinstalling the injector cups, clean them up and replace the O-rings. Then prep the cup by putting red Loctite on the bottom of the cup where it begins to taper. Lube up the O-rings with some Vaseline or oil.
• Be very careful when reinstalling the cups and make sure they go in straight.
• When reinstalling the upper valve cover, seal the top of the high-pressure line fitting. This keeps dirt and debris from building up and dumping inside the injector.
• When reassembling, it is recommended to check your valve lash, especially if you have a lot of miles on your LB7.
• When refilling the radiator, remove the bleed screw to get some air out.

Injector warranty

The injector warranty depends on the product you purchase. For example, InjectorsDirect.com offers a three-year warranty on their brand new BOSCH LBZ injectors, while their refurbished or remanufactured products come with a two-year warranty. Pure Diesel Power offers a 12-month, unlimited-mile warranty on their remanufactured 2006-2007 LBZ Duramax Diesel Bosch Fuel Injectors.

It is worth noting that some sources mention a seven-year, 200,000-mile warranty on injectors, but this may be specific to certain models or years. It is always best to check the warranty information for the specific product you are considering purchasing to understand the terms and conditions of the warranty coverage.

Additionally, some companies may offer extended warranties or protection plans for an additional cost. These plans can provide peace of mind and protect your investment in the event of unexpected repairs or replacements. When purchasing injectors, be sure to carefully review the warranty information to understand what is covered, as well as any exclusions or limitations that may apply.

Injector replacement cost

The cost of injector replacement for a Duramax LBZ engine varies depending on the type of injectors purchased and the source. Remanufactured injectors are generally more affordable than brand-new injectors. Online retailers like Injectors Direct offer individual injectors and full sets of eight injectors. A single remanufactured injector for the LBZ engine can cost around $250-350, while a full set of eight remanufactured injectors can cost around $3,200. On the other hand, brand-new injectors tend to be more expensive, with a set of eight injectors priced at $4,000 or more.

It is worth noting that injector replacement can be a complex task and may require specialized tools and knowledge. While some experienced individuals may choose to replace the injectors themselves, others may prefer to have the work done by a dealership or a trusted mechanic. The labour cost for injector replacement can vary depending on the mechanic or dealership, but it is generally recommended to obtain multiple quotes to ensure a fair price.

Additionally, it is important to consider the maintenance history of the vehicle when deciding on injector replacement. Proper maintenance, such as regular oil changes, fuel filter replacements, and the use of fuel additives, can help extend the lifespan of the injectors. On average, injectors for the Duramax LBZ engine may require replacement around 250,000 to 300,000 miles, but this can vary depending on the usage and maintenance of the vehicle.

Frequently asked questions