Cummins 6.7L Diesel Turbocharger
In 2007, Dodge trucks began using the 6.7L common rail Cummins diesel turbocharger engine, which uses a Variable Geometry Turbocharger (VGT). On the 6.7L, the VGT has a patented one-piece sliding nozzle that continuously moves to vary the power of the turbine and the amount of air delivered to the engine. The movement allows turbine power to be set to provide enough energy to drive the compressor at the desired boost level in all engine operating modes.
Changes in turbine power level are achieved by varying the position of the nozzle ring in relation to a set of guide vanes that control the flow through the turbine. Other VGT designs turn the vanes to achieve different turbine volumes. In this turbocharger, however, the vanes do not pivot. An electronically controlled actuator positions a sliding nozzle ring over the guide vanes. Exhaust gas enters the turbine section of the turbocharger as it leaves the exhaust manifold. Pressure from the exhaust gas causes the turbine to rotate. The turbine is connected by a shaft to the compressor section of the turbocharger. The rotating compressor draws in inlet air, compresses it, and sends the compressed air through the inter cooler to the engine.
Mounted to the turbocharger housing, the Electronically Controlled Actuator consists of an integrated controller and a gear train that controls the position of the sliding nozzle ring. The actuator uses a signal from the ECM to control the relationship between the sliding nozzle ring and turbine blades. Moving the nozzle ring backward or forward redirects the exhaust flow, so the turbine wheel spins faster or slower as needed. If the ring is moved rearward, the turbocharger builds more pressure (wheel moves faster). If the ring is moved forward, the turbocharger builds less pressure (wheel moves slower).
Do not remove the actuator from the turbo housing unless you are sure that your scan tool can perform the locating procedure required for proper assembly.
The VGT Actuator on the 6.7L is water cooled. Coolant is provided through a passage in the bearing housing. Water cooling adds to the reliability and durability of the actuator. When replacing a failed turbo, it is important to check these lines for adequate coolant flow.
Power Tip: Carbon buildup inside the turbo can prevent proper movement of the nozzle and will often set a P2262 insufficient boost code.
When replacing a turbo, it is important to do the following:
- Check for oil and coolant flow to the turbocharger
- Check and/or replace the air filter
- Be sure the oil is clean and has been serviced
- Disable fuel, and crank the engine to prime the turbo and oil lines
- Start the engine and allow it to idle for a few minutes before spooling up the turbo
- Allow the turbo to cool by idling the engine for a few minutes
For more replacement tips for this turbo, watch our Installation Spotlight video: