The thermostat temperature best suited for a 5.7 Hemi typically falls in the 180°F (82°C) to 195°F (90°C) range; confirm the exact spec for your vehicle’s year and model.
The 5.7 Hemi, used in a variety of Dodge, Chrysler, and Jeep applications, relies on the thermostat to regulate coolant flow and engine temperature. The right rating affects warm-up time, heater performance, emissions, and overall drivability. Below we outline common options, how they behave in different conditions, and how to choose the correct one for your vehicle.
Common thermostat ratings for the 5.7 Hemi
Below are the most common thermostat ratings you’ll encounter for the 5.7 Hemi, with notes on typical use and trade-offs.
- 180°F (82°C) thermostat: Pros — quick warm-up, widely used as OEM on many Hemi applications; Cons — engine may run cooler under high load or in very cold climates; heater performance can be slightly cooler at idle.
- 195°F (90°C) thermostat: Pros — keeps engine at a higher operating temperature, which can improve emissions and heater output; Cons — longer warm-up in cold weather and occasionally higher under-hood temperatures in hot climates or with towing.
- 160°F (71°C) high-flow option: Pros — faster warm-up in some cold climates; Cons — higher emissions, cooler exhaust temps, and potential issues with engine sensors and idle quality; not common for modern Hemi vehicles.
- 170°F (77°C) alternative: Pros — moderate warm-up; Cons — may not be ideal for emissions compliance or long-term reliability; less common on newer Hemi engines.
In most daily driving, sticking to the stock 180°F or the OEM-specified 195°F is the prudent choice. If you tow, drive in very cold climates, or are pursuing a performance-oriented setup, you may consider the 195°F option upon consultation with a technician.
Choosing for your vehicle
Consider these factors to determine the right thermostat for your 5.7 Hemi:
- Check the OEM specification for your exact model and year using the owner's manual, service manual, or VIN-specific parts catalog.
- Assess your climate and typical driving conditions—cold starts, highway driving, towing, and climates with extreme heat may influence the best choice.
- Evaluate how a thermostat choice affects cabin heater performance, engine warm-up, and emissions compliance.
- Ensure the aftermarket thermostat matches the engine's cooling system design (high-flow vs standard, gasket compatibility, and sensor placement).
- Consult a dealer or qualified mechanic if you are replacing under warranty or if you operate a modified vehicle (e.g., performance-tuned 5.7 Hemi).
Implementing the correct thermostat helps maintain optimal operating temperature, ensures reliable heater performance, and supports emissions compliance. If you are unsure, aim for the stock spec and consult your vehicle’s documentation or a technician.
Summary
The 5.7 Hemi commonly uses a thermostat rated around 180°F (82°C) to 195°F (90°C). The best choice depends on your vehicle’s year, climate, and usage, with 180°F serving as a typical baseline and 195°F favored by those who tow or operate in warmer climates. Always verify the exact specification for your VIN and consult a professional if you are unsure.