Engine Coolant Thermostat Guide for the 1965-1979 Dodge Monaco
Keep your classic Monaco's engine temperature in check with the right replacement thermostat.
- A stuck-closed thermostat is a critical failure that can quickly lead to severe engine damage from overheating.
- For a stock engine, a standard replacement thermostat from a reputable brand like Gates or Stant is a reliable choice.
- Always verify the correct temperature rating (typically 180°F or 195°F) for your Monaco's specific engine and year.
- Always replace the thermostat gasket to prevent coolant leaks.
Symptoms of a Failing Thermostat
A bad thermostat can fail in two ways: stuck open or stuck closed. Each has its own set of symptoms.
Stuck Open: If the thermostat is stuck open, the engine will take a very long time to warm up, or may never reach full operating temperature. Symptoms include a low reading on the temperature gauge, poor heater performance, and decreased fuel economy.
Choosing the Right Aftermarket Thermostat
For a vehicle from the 1965-1979 era, new OEM parts from Mopar are generally not available. Your only option is a new aftermarket part. The good news is that modern manufacturing can produce high-quality replacements. The key is choosing a reputable brand.
Brand Quality Tiers
- Standard Replacement (Recommended): Brands like Gates and Stant have historically been reliable choices for daily drivers and stock restorations. They offer a good balance of quality and price. While some forum users note that quality can be inconsistent across all brands these days, these are generally considered safe bets.
- Performance Options: Brands like Edelbrock and Mr. Gasket offer high-flow thermostats. These are designed for modified engines with upgraded cooling systems. For a stock Monaco, a high-flow thermostat is not necessary and may not provide any benefit. Some users have reported quality control issues with performance brands, so it's wise to test the part before installation.
- Budget Brands: Motorad is a very common brand found in many parts stores and is even known to be an OEM supplier for some modern cars. However, owner experiences are mixed; some report premature failures or incorrect temperature operation, while others have no issues. If choosing a budget option, it is highly recommended to test it before installation.
Cost to Replace a Dodge Monaco Thermostat
| Part/Service | Estimated Cost |
|---|---|
| New Aftermarket Thermostat | $8 - $56 |
| New OEM Thermostat | Not Available (NOS Only) |
| Shop Labor | $75 - $150 |
Frequently Asked Questions (FAQ)
What temperature thermostat should I use for my Monaco?
Always check the specifications for your specific year and engine. Most classic Mopar engines from this era use a 180°F or 195°F thermostat. A 180°F thermostat will run the engine slightly cooler, which some prefer in hot climates, while a 195°F thermostat is often the stock temperature, promoting better fuel burn and heater performance. Using the OE specified temperature is generally the best practice.
Do I need a special "fail-safe" thermostat?
Some aftermarket thermostats are designed to lock in the open position if they fail, preventing a catastrophic overheating event. While this sounds good, some mechanics report these can fail in the open position without an actual overheating event, leaving you with a cold-running engine. A quality standard thermostat is often a more reliable choice.
Should I replace the gasket and housing?
Yes, you must always use a new gasket when replacing the thermostat to prevent leaks. The thermostat housing itself rarely needs replacement unless it is cracked, heavily corroded, or the bolt holes are stripped. Inspect it carefully when you remove it.
Are there any recalls for the thermostat on my Dodge Monaco?
No, there are no specific recalls issued by the NHTSA for the engine coolant thermostat on the 1965-1979 Dodge Monaco.
Technical Specifications
Common temperature ratings are 180°F and 195°F. Diameter is a critical dimension, typically around 53-54mm for Mopar applications of this era, but always verify fitment for your specific engine.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.