GM diesel work done to spec, from injector cups to Allison shift quality.
Duramax Repair
Every Duramax generation has its own personality. LB7 injectors live under the valve covers; LLY overheats when towing; LBZ and LMM ask about turbo vanes and glow plugs; LML and L5P bring CP4 and emissions questions. We diagnose to the generation, not to a generic diesel checklist.
Allison transmission concerns are handled in-house alongside the engine so the diagnosis is not split between two shops blaming each other.
What's included
Scope of work
- LB7 injector replacement with return-flow verification
- LLY / LBZ / LMM turbo vane cleaning and actuator service
- LML / L5P CP4 and CP3 conversion diagnostics
- Fuel pressure regulator, FCA and lift-pump service
- Glow plug and glow-plug-module repair
- Allison shift-quality diagnosis, service and repair
- Water pump, thermostat and cooling upgrades for towing
- EGR, DPF, DEF and NOx sensor diagnostics
Symptoms we fix
Sound familiar?
- White smoke and hard start on an LB7
- Overheating on grades with a trailer
- Limp mode or boost fault codes
- Fuel in the oil or a rising oil level
- Harsh, late or slipping Allison shifts
- DEF or emissions countdown warnings
How we work it
The four steps, every time
- 01
Generation ID
RPO and VIN decode so parts and procedures match your exact truck.
- 02
Fuel & air testing
Return flow, rail pressure and boost testing separate injector faults from supply faults.
- 03
Repair
Torque-to-spec assembly, new seals and cups, and correct injector programming where required.
- 04
Relearn
Injector balance rates and transmission adaptives are relearned before the truck leaves.
Questions
Straight answers
Do LB7 injectors have extended coverage?
Original GM coverage has long expired on most trucks. We quote the full job including the required programming.
Can you fix an Allison without replacing it?
Often yes. Many shift complaints are solenoid, fluid or adaptive issues, not a failed transmission.
Do you clean turbo vanes or replace the turbo?
We inspect first. A sooted-up vane assembly can be cleaned; a worn shaft or damaged actuator gets replaced.
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Get a straight answer on your truck.
Tell us what it's doing. We'll tell you what it takes — in writing, before any work starts.