GMC Duramax Repair | GMC Duramax Service

GMC Duramax Repair Service

GMC Sierra HD trucks earn their keep every day. We support them with brand-aware diagnostics, Genuine GM parts, and tight communication—Sierra 2500/3500 HD pickups, cab-and-chassis upfits, and legacy medium-duty TopKick/Kodiak.

Diagnostics & Common Repairs

Test-first workflow to fix root cause, not just clear codes.

Low power/limp & regens: DPF/DEF/SCR, diff-press, NOx/EGT sensors, heater/line faults, dosing tests
Turbo/air: VGT actuator, vane sticking, CAC/boot leaks, intercooler integrity, MAP/MAF contamination
Fuel system: rail pressure/return, balance rates, filter head issues, CP3/CP4/Denso HP pump tests, injector service
Cooling & oiling: thermostats, water pump, radiator/cooling-stack service, fan clutch, EGR & oil cooler
Electrical/starting: glow plugs & module, batteries/alternator, voltage-drop/grounding
Chassis: brakes, hubs, U-joints, steering/suspension, 4×4 vacuum/engagement

Engines & Platforms We Service

6.6L Duramax: LB7, LLY, LBZ, LMM, LML, L5P across Sierra 2500/3500 HD
Cab-and-chassis/upfits: service bodies, dumps, crane/utility rigs
Also supported (where equipped): 2.8L LWN in Savana and select fleet units

Major Repairs — Engine

Verification: relative compression/leak-down, balance rates/return flow, rail pressure, boost/CAC smoke test, cooling pressure/flow, oil analysis
Fuel restorations: CP4 contamination (LML) complete system remediation; L5P HP pump/injector service; LB7 injector/line updates
Turbo & air: VGT service/replacement, actuator calibration, CAC/intercooler replacement
Top-end & gaskets: head gaskets/fastener strategy, valve train, timing set
Cooling-stack refresh: radiator/CAC/cond, fan hub/clutch, thermostats, water pump, hoses/surge tank
Aftertreatment integration: DPF clean/replace, DOC/DEF components, NOx/EGT calibration
Validation: hot/cold starts, grade road test, leak/boost checks, datalog packet

Major Repairs — Transmission

Allison 1000/2000 and 10-speed pairings.

Diagnostics: TCM codes, adaptives, line pressure, range switch, harness/grounds, cooler flow/temps
Service/repair: correct fluids (TES-295 / Dexron ULV), filters, seals, sensors, valve body/solenoids, cooler & lines
Rebuilds/reman: clutches, converter; approved reman options
Calibrations: adaptive reset/learn, shift-quality verification, PTO checks
Validation: temperature-controlled drive, no-drip recheck, printed fluid specs/intervals

Preventive Maintenance & Fleet Programs

Duty-cycle-based intervals; oil & GM fuel filters, separator drains, coolant test/exchange, CAC/boost integrity, axle/transfer case fluids, brake service, wheel-end torque, batteries/charging, glow-plug tests, tires/TPMS & alignment. Fleet support: priority slots, PM calendars, consolidated billing, proactive advisories.

BIT/DOT Compliance

Inspection prep and quick corrections (lighting, brakes, leaks, tires, steering/suspension) with VIN-level records.

Schedule GMC Duramax service with confidence at Britt’s Diesel—brand-savvy diagnostics, durable repairs, and documentation fleets trust.

Local Shop

Local diesel repair & tire shop in Bishop, CA—fast diagnostics, quality parts, fair estimates, and quick turnarounds.

Skilled Mechanics

Experienced, skilled mechanics—quality diesel repair and maintenance you can trust every time.

Quality Equipment

From advanced diagnostics to heavy-duty lifts and equipment, we have the tools to service with precision.

Benefits of Service

Maximize uptime, minimize surprises. Proper, test-first service with OEM fluids/filters, fuel & air system verification, turbo/aftertreatment checks, and Allison-friendly procedures delivers stronger pulling power, fewer regens, better MPG, longer component life, and lower cost per mile.

GMC Duramax Service FAQs

Quick answers about GMC Duramax service at Britt’s Diesel—Sierra 2500/3500 & 4500–6500, 6.6L Duramax from LB7 to L5P, test-first diagnostics for power loss/regens, engine & Allison transmission repairs, PM for towing/heavy use, and fleet/BIT-DOT support

01. Which GMC models and engines do you service?

Sierra 2500/3500 HD pickups and cab-and-chassis upfits (service body, dump, crane), plus 4500/5500/6500 medium duty. Engines: 6.6L LB7, LLY, LBZ, LMM, LML, L5P (and 2.8L LWN where equipped).

02. How do you diagnose low power, limp mode, or frequent regens?

A test-first workflow: live data logs, rail pressure & return, injector balance rates, boost/CAC smoke testing, MAP/MAF verification, DEF/NOx/EGT sensor checks, cooling performance, and 12V voltage-drop/ground tests—so fixes target root cause.

03. Do you handle major engine and Allison transmission work?

Yes. Engine: CP4 contamination remediation (LML), L5P high-pressure pump/injectors, LB7 injector/line updates, turbo/VGT service, head gaskets, cooling-stack refresh. Transmission: Allison 1000/2000/10-speed diagnostics, fluid/filters to spec (TES-295/Dexron ULV), valve body/solenoids, rebuilds or reman swaps, and adaptive reset/learn.

04. What preventive maintenance is best for towing/heavy use?

GM-spec oil & fuel filters, water-separator drains, coolant test/exchange, CAC/boost integrity, axle/transfer case fluids, brake fluid/pads, hub & wheel-end torque, batteries/charging, glow-plug system checks, and tire cold PSI/TPMS. Follow severe-duty intervals.

05. Can you support fleets and compliance?

Absolutely—priority scheduling, PM calendars (miles/hours/date), consolidated invoicing, digital service records, and BIT/DOT pre-inspection with fast corrections (lighting, brakes, leaks, steering/suspension, tires).

Service

GMC Duramax