What temperature thermostat for 5.7 hemi?
The typical thermostat temperature for a 5.7 Hemi is 195°F (90°C). This is the standard spec used in most Mopar-engineered vehicles with the 5.7 Hemi, balancing warm-up speed, engine efficiency, and emissions. Some enthusiasts consider 180°F in very cold climates or for specific performance goals, but 195°F remains the recommended all-around option for daily driving.
Stock thermostat temperature for the 5.7 Hemi
Understanding the baseline helps explain why 195°F is widely used. The thermostat's opening temperature controls when coolant starts circulating through the radiator. At about 195°F, the engine reaches its optimal operating temperature quickly enough to maintain performance and emissions standards, while still allowing the cooling system to manage heat under heavy load or hot conditions.
Common thermostat options and trade-offs
Below are the temperature options you’ll encounter for the 5.7 Hemi and what they typically mean in practice.
- 195°F (90°C) – The stock or standard replacement. Provides reliable warm-up, steady operating temperature, and good emissions performance for most driving conditions.
- 180°F (82°C) – A popular aftermarket choice for faster warm-up and improved cabin heat in very cold climates. May cause the engine to run cooler longer, which can affect fuel trim and emissions readiness in some conditions.
- 160°F (71°C) – Rare for daily driving; used only in very specific builds or extreme cold scenarios. Can lead to longer catalytic converter warm-up times and potential performance detriments if the engine never reaches its designed operating temperature.
When choosing among these options, climate, towing duties, and personal preference for heater output should factor in. For most drivers, the 195°F thermostat remains the safest and most balanced choice.
Installation and maintenance tips
Installing a thermostat in a 5.7 Hemi is a straightforward task if you follow proper procedure and safety steps. The thermostat sits in the water outlet housing connected to the radiator hoses, so correct orientation and a good gasket seal are essential for reliable operation.
- Drain coolant and disconnect the battery before starting work.
- Remove the thermostat housing, take out the old unit, inspect the seating surface and gasket, and replace with a new gasket or O-ring.
- Install the thermostat with the correct orientation (spring side toward the engine, standard for most designs) and reseal the housing with a fresh gasket. Refill coolant to the proper level and bleed air if your vehicle requires it.
- Run the engine and monitor for leaks and proper temperature operation. Ensure the cooling fan engages and coolant temps stabilize near the target range.
Use a reputable brand (OEM Mopar, Gates, Dorman, Mahle, etc.) and verify compatibility with your exact model year to minimize fitment issues and ensure long-term reliability.
Impact on temperature readings and engine performance
Thermostat choice interacts with the radiator capacity, ambient temperature, and vehicle load. A cooler thermostat can shorten warm-up time but may keep the engine cooler in steady-state operation, potentially affecting fuel economy and emissions readiness. The standard 195°F thermostat works well with the factory cooling system to keep the engine in its optimal range during most conditions.
Will a different thermostat affect fuel economy or emissions?
Yes, to some degree. A lower opening temperature (like 180°F) can delay catalytic converter warm-up and may slightly worsen emissions readiness or fuel trim until the engine reaches its operating temperature. For everyday driving, the 195°F thermostat is typically the best balance of performance, efficiency, and emissions.
Summary
For most 5.7 Hemi owners, the recommended thermostat temperature is 195°F (90°C). A 180°F option can be considered in very cold climates or for specific warmth-up preferences, but it carries potential trade-offs in emissions and fuel economy. Always confirm compatibility with your exact year and configuration, and choose a trusted brand with proper installation to maintain reliable cooling and engine performance.
What is the best temperature thermostat for a 5.7 Hemi?
RIPP 180 Degree Thermostat for 5.7L and 6.4L V8 HEMI Engines. An efficient cooling system is essential for your HEMI V8 engine. The RIPP thermostat increases the efficiency of your engine's cooling system by opening at 180°F, compared to your vehicle's standard thermostat, which opens at 203°F.
Is a 180 or 195 thermostat better?
A 180-degree thermostat opens earlier, allowing coolant to flow sooner to keep the engine cooler, while a 195-degree thermostat lets the engine run hotter before opening. For most modern vehicles, the 195-degree thermostat is recommended as it is designed for the engine's stock efficiency and emissions control. However, a 180-degree thermostat is suitable for performance or modified engines where cooler temperatures are desired, provided the cooling system is adequate to handle the heat.
| Feature | 180-Degree Thermostat | 195-Degree Thermostat |
|---|---|---|
| Operating Temperature | Allows coolant to flow at 180°F, keeping the engine temperature lower. | Allows coolant to flow at 195°F, letting the engine run hotter. |
| Engine Efficiency | Can be less efficient, as some fuel may not burn completely at lower temperatures, but can reduce detonation risk. | Optimized for stock efficiency and emissions control. |
| Performance | Better for performance or modified engines that run hot, and provides a larger buffer against overheating. | Stock temperature for most modern cars; higher temps can lead to better fuel burn. |
| Overheating | If an engine overheats with a 195-degree thermostat, it will also overheat with a 180-degree one, as overheating is a separate issue with the cooling system. | If an engine runs fine with a 195-degree thermostat, a 180-degree may lead to it running slightly cooler without issues. |
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When to use which thermostat
- Use the 195-degree thermostat:
- For most modern cars to maintain designed efficiency and emissions performance.
- If you want the engine to run at its optimal operating temperature for the vehicle's design.
- Use the 180-degree thermostat:
- In performance or modified engines where cooler running temperatures are beneficial.
- If you have a stock engine that runs hotter than the stock thermostat's operating temperature, as it provides a larger buffer.
What is the normal operating temperature for a 5.7 Hemi?
The normal operating temperature for a 5.7 Hemi engine is typically between 195°F and 220°F for the coolant. However, temperatures can fluctuate based on driving conditions, with some modern engines designed to run efficiently at the higher end of this range (around 203°F). It is critical to avoid temperatures above 220°F220 degrees cap F220°𝐹 to prevent overheating.
Normal temperature ranges
- Coolant: A healthy 5.7 Hemi will generally run between 195−220°F195 minus 220 degrees cap F195−220°𝐹.
- Idle: At idle, especially with the AC on, the temperature might hover between 208−213°F208 minus 213 degrees cap F208−213°𝐹.
- Driving: While cruising, the temperature is often in the 197−204°F197 minus 204 degrees cap F197−204°𝐹 range.
What to watch for
- High temperatures: If the temperature consistently goes above 220°F220 degrees cap F220°𝐹, especially under load, it can be a sign of a problem, such as a failing water pump, a leak, or a faulty thermostat.
- Overheating: If your temperature gauge enters the red zone, stop the car immediately to prevent serious engine damage.
- Engine performance: Running too hot can lead to issues like warped cylinder heads or piston seizure. Conversely, running too cold can negatively affect fuel efficiency and computer-controlled systems, which are tuned for optimal performance at higher temperatures.
What temperature thermostat for 2012 Ram 1500 5.7 Hemi?
Engine Thermostat 52028898AE,203℉ For 2003-2018 Ram 1500 2500 3500 5.7L & Dodge Challenger Charger Durango Magnum 5.7L,6.1L,6.2L,6.4L & Jeep Commander Grand Cherokee 5.7L,6.1L,6.4L & Chryslers 300.
