Dodge Aries 1981-1989 Engine Coolant Thermostat: A Mechanic's Guide
Don't let a simple, inexpensive part cause major engine trouble in your classic K-car.
- A thermostat failing in the 'stuck closed' position will cause rapid overheating; pull over immediately to prevent engine damage.
- The 2.2L and 2.5L engines are known to trap air; drill a small 1/16" bleed hole in the new thermostat's flange to prevent air pockets.
- Always use the factory specified 192°F or 195°F thermostat; a different temperature won't fix other cooling system issues.
- Overheating symptoms can also be caused by a failing head gasket, a known weak point on some of these engines.
Is Your Aries Thermostat Failing?
A thermostat can fail in two ways: stuck open or stuck closed. The symptoms are very different, but both mean you need a new part.
| Failure Mode | Symptoms |
|---|---|
| Stuck Open | Your engine takes a very long time to warm up. The temperature gauge on the dash stays low, and the heater blows lukewarm or cold air. You may also notice worse gas mileage because the engine isn't running at its efficient temperature. |
| Stuck Closed | This is a serious problem. The temperature gauge will shoot into the red very quickly, often within minutes. You might see steam from under the hood or hear boiling and gurgling sounds. Pull over and shut off the engine immediately to prevent catastrophic damage like a warped cylinder head. |
Vehicle-Specific Known Issues
Warning: Check the Head Gasket
The 2.2L Chrysler engine, common in the Aries, was known to have issues with head gaskets. A failing head gasket can push combustion gases into the cooling system, causing overheating that looks exactly like a stuck thermostat. If you replace the thermostat and the car still overheats, a bad head gasket is a strong possibility.
Pro Tip: Bleeding Air from the System
The 2.2L and 2.5L engines in these cars are notorious for trapping air in the cooling system after it has been drained and refilled. This trapped air can cause an air pocket behind the thermostat, leading to overheating even with a brand new part. To prevent this, many mechanics drill a tiny 1/16-inch hole in the flange of the new thermostat before installing it. This allows trapped air to escape, making it easier to properly bleed the system.
🎬 See this expert video on how to bleed a cooling system.Choosing the Right Aftermarket Thermostat
For a vehicle of this age, original Mopar thermostats are not readily available. The aftermarket is your only realistic choice. Fortunately, thermostats are a simple, proven technology, and several reputable brands offer reliable replacements. The quality difference between the major aftermarket brands for a basic part like this is minimal.
- Gates: A well-respected name in cooling system parts like belts and hoses, their thermostats are considered a reliable, standard choice.
- Motorad: One of the largest thermostat manufacturers in the world. They produce thermostats that are often repackaged and sold under other brand names. While some DIY forums have mixed reviews, they are a major OEM supplier and a common aftermarket part.
- Beck Arnley: This brand specializes in sourcing parts and often re-boxes components from other manufacturers, which could even be Motorad. They are generally considered a quality source for aftermarket parts.
- Calorstat: A well-regarded European brand, often known for being an OEM supplier. Quality is generally considered to be very good.
Ultimately, choosing the correct temperature rating (192°F or 195°F) and ensuring a proper, air-free installation is more critical than which of these brands you choose.
Estimated Replacement Costs
Replacing the thermostat on an Aries is one of the most affordable repairs you can make. The part itself is inexpensive, and the labor is straightforward for any mechanic or DIYer.
| Item | Estimated Cost |
|---|---|
| New Aftermarket Thermostat & Gasket | $9.85 - $26.86 |
| Shop Labor | $100 - $180 |
| Total (Shop Repair) | $110 - $207 |
| Total (DIY Repair) | $10 - $27 (plus coolant) |
Frequently Asked Questions
What temperature thermostat should I use?
You should use the factory-specified temperature, which is typically 192°F or 195°F for the Dodge Aries. Using a lower temperature thermostat will not solve an overheating problem and will cause the engine to run too cool, hurting fuel economy and performance.
Should I replace the gasket too?
Yes, always. The thermostat gasket is a single-use part that ensures a leak-free seal. A new gasket is very cheap and should come with the thermostat or be purchased separately. Reusing the old gasket will almost certainly cause a coolant leak.
Is this a good DIY job?
Yes. For most people with basic hand tools, this is a very manageable DIY repair. The thermostat is located at the top of the engine where the upper radiator hose connects to the thermostat housing. 🎬 Watch: How to find and replace your engine thermostat. The job involves draining some coolant, unbolting the housing, swapping the part and gasket, and then refilling and bleeding the system. The most difficult part is usually cleaning the old gasket material off the metal surfaces.
🎬 Watch: A step-by-step guide to replacing a bad thermostat.Are there any recalls for the Dodge Aries thermostat?
No, there are no specific safety recalls issued by the NHTSA for the engine coolant thermostat on the 1981-1989 Dodge Aries.
Helpful Videos
Technical Specifications
OEM Part Numbers: 4104442 4105404 4105442 4105768
Standard Temperature: 192°F or 195°F.
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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.
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