2017-2019 6.6L GM Duramax L5P

Lift Pump - Injectors - Injection Pump

December 2018

Model year 2017 marked some major changes for the Duramax fuel system. Finally, they forewent the status quo that had been hovering over this engine since 2001 with the only major change occurring in the 2011 model years with the LML engine. The fuel system featured on the L5P could best be described as a 100% complete overhaul. Without going into a complete analysis, lets give you some of the highlights at least. Number one, a fuel pump from the factory. That's right, the main cause for fuel starvation, especially on modified Duramax engines, has been addressed with the addition of a factory lift pump. And we'd say its about time, as every single other manufacturer realized this years ago. Next, you won't be seeing any Bosch insignia on your fuel system.

Again, since 2001, they've been in bed with Bosch to deliver the high pressure fuel via common rail (and later piezo) injectors and a high pressure CP3 or CP4 injection pump. Well, GM and Bosch apparently had a divorce and Denso came knocking. The Bosch CP4 found on the LML engines has been replaced by a Denso HP4 that should eliminate the countless failures of the CP4. Why? Many would attribute the failures to the roller tappet design that would self destruct at the presence of any air where the HP4 uses a much more robust solid lifter design that is also a substantially simpler design. As previously stated, Denso is also supplying the injectors with a solenoid type that replaces the Bosch piezo units found in the 2011-2016 model years. This move wasn't necessarily due to a high failure rate of the piezo injectors, more so because the solenoid type work more cohesively with the HP4 and the rest of the fuel system. 

Again, these are merely the highlights of the move from Bosch to Denso with basically every other facet of the injection system changing in some degree, as well. Now, the question at hand, what's to be improved from this system? Well, time will tell as far as the true weaknesses, but for those looking to produce power levels above stock, there is definitely room for improvement. While a lift pump has indeed been integrated from the factory, its output is sub par and will need an upgrade to allow for fuel delivery to match most of the programmers on the market. The HP4 is absolutely more robust than a CP4 in terms of durability, but again, not capable of delivering sustained rail pressure for maximum power potential. How far will fuel upgrades take you and your L5P Duramax to meet your power goals?

As always, if you are having any issues determining the right parts for you and your truck, do not hesitate to give us a call at 801-517-7780 or send an e-mail to info@gillettdiesel.com and we would be happy to assist.

 

How to Recognize and Diagnose a Damaged Turbo - Septmeber 2018

Vehicle manufacturers are adding turbos at an extraordinary rate, and over the coming years, the turbo market is expected to grow to more than eight million turbocharged vehicles. As this number of turbocharged vehicles increases, more technicians and vehicle owners will see vehicles with turbocharger issues. Unfortunately, there's already confusion in diagnosing turbo problems. Here's a comment from one of our customers

"How can I visual check a turbo to help know when a new turbo is needed."

To help technicians and vehicle owners diagnose turbocharger repairs, here are a few important diagnostic and repair tips to keep in mind. As a note upfront, most turbocharger diagnoses (aside from noise and low power issues) require scan data and an understanding of operation at the technician-level.


What Causes a Turbocharger to Malfunction 

Bad Turbo

Symptoms of a malfunctioning turbocharger include loss of power, excess smoke, high fuel consumption, overheating, high exhaust temperature, and oil leaks from the turbo. But it’s important to note that defects in other components can produce the same symptoms. Before wrongly attributing the issues to the turbo, remember that turbo performance can only be impaired by mechanical damage or blockage caused by debris.


Signs of a Damaged Turbocharger

 

If you hear whistling noises coming from the turbo, it’s likely due to an air leakage caused by pre-turbine exhaust gas or air leaks. To narrow the diagnoses first check all of the joints. If the noise continues, check the turbocharger clearances and wheels for housing contact.

If the turbocharger rotor assembly has seized up or is difficult to rotate, the problem is likely tied to the break down of the lubricating oil. When the oil degrades, it can lead to carbon buildup in the bearing housing. The carbon buildup will restrict rotation. Two other issues that can cause the rotor to seize up include insufficient or intermittent drop-in oil pressure and dirt in the lubricating oil. Another important detail to keep in mind is that a turbocharger has specific axial and radial rotor clearances. Sometimes, the clearances can be misdiagnosed as worn bearings. In reality, clearances that are out of specification may be associated with a lubricating oil issue. Check for insufficient oil, dirt, and oil contamination with coolant.

To determine if the turbo has been damaged by foreign material, inspect the turbine wheel or impeller. You will clearly see any foreign material that has entered through the turbine or compressor housings. If the blades are damaged, the turbo is already destroyed. Look for metal that has come off the turbo in the intake tubes. Metal particles in this area may indicate a damaged engine.


Common Trouble Codes

Two typical diagnostic trouble codes for turbos include Boost Codes (underboost) or (overboost), and Actuator codes. If you’re receiving an underboost code, the issue could be a wastegate that’s stuck in the open position or a leak between the compressor and throttle. Causes of overboost, on the other hand, include a wastegate that’s stuck in the closed position, a wastegate vent solenoid that’s stuck in the vent position, or leaking or disconnected control hoses.

When diagnosing and repairing boost-related trouble codes, here’s a helpful repair tip to keep in mind: turbocharger operation can be affected by a dirty intake air temperature sensor. That’s because the dirty sensor is unable to pass temperature differences quickly enough. To fix the issue, remove the intake air temperature sensor from the intake manifold and clean it using either carburetor cleaner or bead blast.


Choose the Right Replacement

Once you’ve diagnosed your turbo and determined that you need a replacement unit, remember that Gillett Diesel Service offers both 100% new and quality remanufactured turbochargers.

Using extensive research to determine the numbers needed to compete in the turbo market, Gillett Diesel offers full-line coveragefor all turbo applications. Gillett Diesele also offers an array of related components, including turbo actuators, turbo oil drain tubes, and turbo speed sensors. 

Browse our extensive inventory of turbos and turbo part

 

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