Chevy Silverado HD and GMC Sierra HD service. Every generation: LB7, LLY, LBZ, LMM, LML, L5P. Injectors, glow plugs, Allison 1000 transmission, fuel system. We service the trucks Northern Colorado runs hard.
If your vehicle is showing any of these, bring it in. Most are addressable; all deserve real diagnosis before parts are thrown at the problem.
The LB7 and LLY have completely different injector platforms. The LBZ runs differently from the LMM. The LML’s CP4 fuel pump is built differently from the LMM’s CP3. Diagnosis on a Duramax has to start with “which Duramax is this” — and that matters for parts, procedures, and timing.
We use GM GDS2 and Tech 2 scan tools for Duramax diagnostics. We’ve done LB7 injector jobs, LMM DPF cleaning, LML fuel system replacements, and L5P emissions work hundreds of times. AC Delco and Bosch parts where they belong. Allison transmission service done with the correct fluid and updated TSB-mandated procedures.
We do not perform DPF, EGR, or DEF deletes. We service emissions-legal Duramax trucks only.
On the LB7, 100,000–150,000 miles is typical before injector cup or body failure. Newer generations (LBZ, LMM, LML, L5P) often go 200,000+ with quality fuel and disciplined filter service. Symptoms of failure include rough idle, white smoke at idle, fuel-in-oil rise, and CEL codes.
The 2004–2006 LLY has a documented airflow restriction issue: the radiator and intercooler are smaller than the engine demands when towing at altitude. We diagnose for actual head gasket vs cooling system limitation, then repair or upgrade accordingly. Larger transmission cooler and thermostat upgrade often address it without engine work.
Yes. The Allison 1000 (in all Duramax HD trucks) is a strong transmission but needs disciplined service: fluid changes at 50,000 miles, filter replacement, and torque converter monitoring. We do full Allison service and full rebuild on case-by-case basis.
The L5P uses a different CP4 design than the 6.7 Power Stroke and has a much better failure track record. We don’t recommend proactive replacement on the L5P. We do recommend disciplined fuel filter service and quality fuel only — both apply to any modern diesel.
Most appointments available within 48 hours. Free estimate. Photo inspection. A real person who answers the phone.