GM 97241129 Duramax Front Thermostat (6.6L LB7 | LLY | LBZ | LMM | LML)

Genuine OEM GM / ACDelco Front Coolant Thermostat – 185°F

Restore factory cooling performance and precise temperature control in your GM 6.6L Duramax with this genuine OEM front thermostat (GM 97241129 / ACDelco 131-163). Designed as a direct drop-in replacement for the forward-mounted thermostat, this unit maintains the OE-specified 185°F opening temperature for optimal engine warm-up, consistent operating temperature, fuel efficiency, and emissions performance.

Key Features & Benefits

• Genuine OEM Quality — Factory GM part engineered to exact OE specifications for fit, form, and function
• 185°F Opening Temperature — Correct front thermostat rating for Duramax dual-thermostat system
• Includes Integrated Seal/Gasket — Rubber seal ring pre-attached for leak-free installation
• Symmetrical Design — Easily identifies as the front thermostat (vs. offset rear unit)
• Responsive Wax-Pellet Actuator — Provides accurate and reliable temperature regulation under all operating conditions
• Direct Replacement — No modifications required; installs in the forward position of the thermostat housing

Why Replace the Front Thermostat?

A failing thermostat is a common issue on higher-mileage Duramax engines. Symptoms of a bad thermostat include:

• Overheating or running too cool
• Poor heater performance
• Reduced fuel economy
• Check engine lights or limp mode related to coolant temperature

Replacing the thermostat(s) is especially recommended during water pump service or any major cooling system work.

Recommended Service Notes

• The front and rear thermostats work together in the Duramax’s dual-thermostat system (rear thermostat is GM 97241130 / 180°F).
• When performing this job, strongly consider replacing the upper radiator pipe seal and oil filler tube seal (sold separately) to prevent coolant leaks.
• Always use the correct coolant and follow proper bleeding procedures after installation.

Vehicle Fitment

Fits 2001–2016 GM 6.6L Duramax (and select later models):

• LB7 (2001–2004)
• LLY (2004.5–2005)
• LBZ (2006–2007)
• LMM (2007.5–2010)
• LML (2011–2016)

Applications include:

• Chevrolet Silverado 2500HD / 3500HD
• GMC Sierra 2500HD / 3500HD
• Chevrolet Express / GMC Savana vans with 6.6L Duramax

Note: Confirm exact fitment with your VIN. This is the front thermostat only.