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If you drive a Ram 3500, a properly functioning thermostat matters for engine longevity, cabin comfort, and towing reliability. Picking the right Ram 3500 thermostat helps maintain correct operating temperature under heavy loads and varied climates, reducing the risk of overheating or inefficient warm-up. This guide presents our shortlisted top picks for the Ram 3500 thermostat and explains the key factors we used to evaluate each option, including fitment specifics and thermal response. Read on for practical guidance before you choose a replacement.
Looking for other parts? See all Ram 3500 parts & accessories.
Top Picks at a Glance
| Best overall The best all-around choice for most situations | Gates 33915 Engine Coolant Thermostat |  |
| Best quality Built to a higher standard if you want something more solid | Sixity Auto Gates Engine Coolant Thermostat for Ram 2500 6.7L L6 (2013–2019) |  |
| Best Value The sweet spot between price and what you get | A-Premium Engine Coolant Thermostat with Seal (fits Ram 1500/2500/3500 and select Chrysler, Dodge, Jeep models) |  |
| Best Budget The cheapest option that still gets the job done reliably | MotoRad 426-180 Engine Coolant Thermostat |  |
| Highest Rated A top-rated pick with lots of positive feedback | RICHWEI Engine Thermostat 203°F (52028898AE Compatible) |  |
| Most Popular A crowd favorite that many people choose with confidence | JXGZYD Engine Thermostat 52028898AE (203°F) for Ram 1500/2500/3500, Dodge, Chrysler, Jeep |  |
| Best Seller A high-volume bestseller chosen again and again | MotoRad 7416-203 203°F Fail-Safe Thermostat |  |
1. Gates 33915 Engine Coolant Thermostat
| Manufacturer Part Number | 33915 |
|---|---|
| Manufacturer | GATES |
| OEM Part Number | 5011456AA, 5086739AB, 5292712, 68005464AA, 68005464AB |
| Included Components | Engine Coolant Thermostat |
The Gates 33915 is a straightforward engine coolant thermostat built to replace the factory unit on Ram 3500 Cummins engines. It uses a positive piston thermostatic element and sturdy metal construction to open and close at its calibrated temperature, helping the engine reach and hold normal operating temperature. Typical use is as a direct replacement during routine cooling-system service or when the truck is running too cool or exhibiting wide temp swings. Buyers will notice consistent temperature control reported by users, simple installation and a factory-calibrated mechanism that resists pressure-related variations. Limitations are that the part does not include visible temperature markings on the housing and long-term durability can vary by operating conditions, so results depend on proper installation and compatible housing/gasket condition. This is a practical, no-frills replacement for Ram 3500 owners who want predictable cooling behavior without modifying the stock cooling strategy.
Best for: Balanced, practical Ram 3500 owners who want a reliable factory-quality replacement to restore stable operating temperatures without performance modification.
Less Ideal for: Owners seeking performance or modified cooling behavior, or those who need a complete housing gasket kit delivered with the thermostat.
- Factory-calibrated thermostatic element for consistent open/close temperature
- Positive piston design reduces sensitivity to pressure changes
- Sturdy metal construction for a robust feel
- Direct-fit replacement for Dodge Ram 3500 Cummins applications
- No temperature marking on the thermostat body to confirm set point
- Does not include housing or gasket, which may be needed for complete replacement
Verdict: A dependable, factory-calibrated replacement thermostat that restores stable coolant temperatures for Ram 3500 Cummins trucks without tuning or extra parts.
2. Sixity Auto Gates Engine Coolant Thermostat for Ram 2500 6.7L L6 (2013–2019)
| Brand | Sixity Auto |
|---|---|
| Manufacturer | Sixity Auto |
| Manufacturer Part Number | 4036024480 |
| Compatible Vehicles | Ram 2500 6.7L L6 2013-2019 |
This thermostat is a direct replacement designed to control coolant flow and maintain operating temperature in the 6.7L Cummins Ram 2500 from 2013 through 2019. It installs in place of the factory unit and is used whenever a failed thermostat causes overheating, poor warm-up, or cooling system faults. The listing highlights Gates-brand compatibility and includes the sealing hardware needed for a straightforward swap. In practice the unit should restore proper thermostat operation and temperature regulation, helping the engine reach and hold its intended temperature under load. Limitations to note are fitment scope and that the listing targets the Ram 2500 6.7L L6; if your vehicle is a Ram 3500 this part may not be confirmed for fitment and you should verify compatibility before purchase. Expect a simple mechanical replacement with no electronic controls and the usual need to bleed and refill the cooling system after installation.
Best for: Performance-oriented buyers who prioritize reliable, factory-style temperature control and want a straightforward replacement part to return a diesel engine to correct operating temperature.
Less Ideal for: Shoppers seeking thermostat options specifically validated for Ram 3500 models or those who want advanced thermostats with variable or electronically controlled temperature management.
- Direct-replacement design intended to match factory thermostat function
- Includes seal and hardware for one-step installation
- Compatible with 6.7L L6 Ram 2500 model years 2013–2019, simplifying fit confirmation
- Branded Gates part compatibility suggests factory-quality design and combustion-cooling reliability
- Fitment is specified for Ram 2500 6.7L models and not listed for Ram 3500 in the product details
- No electronic or adaptive temperature control features compared with some modern thermostats
Verdict: A factory-style replacement thermostat for 6.7L Ram 2500s that restores standard temperature control but is not confirmed for Ram 3500 fitment.
3. A-Premium Engine Coolant Thermostat with Seal (fits Ram 1500/2500/3500 and select Chrysler, Dodge, Jeep models)
| Start to Open Temperature | 95 C |
|---|---|
| Package Quantity | 1 |
| Voltage | 12 Volts (DC) |
This A-Premium thermostat is a direct-fit replacement intended to regulate coolant flow and keep the engine within its designed operating temperature. It is typically used when a failing thermostat causes overheating or poor warm-up performance and is installed in place of the factory unit. The part arrives boxed with a seal and claims a 95 C start-to-open rating, which matches the operating point for many Mopar V8 engines and helps the cooling system open at the right time. Practical benefits include straightforward fitment for covered Ram 1500/2500/3500 model years, a claimed durability from hardness and crush tests, and compatibility with common OEM reference numbers so it integrates with the stock housing and sensors. Limitations are that aftermarket tolerances can vary from factory parts and long-term life depends on installation and thermostat housing condition. The product also lists a one-year unlimited-mileage guarantee but buyers should confirm fitment for specific Ram 3500 model years and engine variants before installation.
Best for: A practical optimizer who wants a budget-friendly, direct-replacement thermostat that restores correct operating temperature on Ram trucks without paying for dealer parts.
Less Ideal for: Owners seeking exact factory-sourced parts for long-term warranty alignment or those working on Ram 3500s with uncommon engine variants should consider factory-quality replacements.
- Direct-fit compatibility with many Ram 1500/2500/3500 model years and common Mopar reference numbers
- Start-to-open temperature specified at 95 C for consistent warm-up behavior
- Includes seal and ships in a box for complete replacement installation
- Backed by a one-year unlimited-mileage guarantee from the brand
- Aftermarket manufacturing tolerances may differ from factory units which can affect long-term reliability
Verdict: A cost-conscious, direct-fit thermostat that restores proper cooling control for many Ram trucks while offering clear temperature spec and a one-year guarantee.
4. MotoRad 426-180 Engine Coolant Thermostat
| Brand Name | MotoRad |
|---|---|
| Model Name | 426-180 |
| Material Type | Copper |
| Item Type Name | Engine Coolant Thermostat |
| Included Components | 1 Motorad branded product |
The MotoRad 426-180 is a simple, factory-replacement style thermostat built to control coolant flow and stabilize engine temperature on compatible Ram 3500 trucks. It installs in the thermostat housing like a standard unit and is intended to hold the engine at its designed operating range to reduce overheating and improve steady-state economy when towing or hauling. The listing and images indicate copper construction and a MotoRad-branded stamped assembly, and several user reports note it comes with a gasket preinstalled. In real-world use buyers report lower cruising temps and quicker cooldown after heavy loads, which helps when towing. There are mixed long-term reliability reports so expect variation between units; one reviewer reported a premature failure that led to overheating. This is a budget-focused replacement that delivers OEM-style function for owners who want an inexpensive fix, but if you need guaranteed heavy-duty longevity for continuous severe-duty towing you may prefer a premium or OEM-sourced thermostat.
Best for: Budget-conscious Ram 3500 owners who need a low-cost, straightforward replacement thermostat to restore normal engine temperature control while towing or daily driving.
Less Ideal for: Owners who run continuous heavy-duty towing or need the highest long-term durability should consider a heavy-duty aftermarket or factory-quality thermostat instead.
- Designed as a direct replacement for applicable Ram 3500 cooling systems
- Copper construction and MotoRad manufacture for basic durability
- Often ships with a gasket already installed for easier installation
- Reported to lower cruising temperatures and improve cooldown after heavy loads
- Some customer reports of premature failure and unit sticking closed
- Mixed consistency in how quickly the valve opens under boil test conditions
Verdict: A no-frills, budget-friendly thermostat that restores factory-style temperature control for Ram 3500 owners who want a low-cost replacement.
5. RICHWEI Engine Thermostat 203°F (52028898AE Compatible)
| Manufacturer | RICHWEI |
|---|---|
| Model | JWQ-4 |
| Manufacturer Part Number | 52028898AE |
| Temperature Rating | 203℉ |
This RICHWEI thermostat is a direct-replacement style unit set to open at 203°F and intended for Chrysler-family V8 engines including Ram 3500 5.7L applications. It installs like a stock thermostat and is used to regulate coolant flow so the engine reaches and holds the designed operating temperature. The metal construction and supplied seal mean it behaves like a factory-style part, and multiple owner reports show it holds temperature in the low 200s once fitted. Practical benefits include straightforward installation for a DIYer and compatibility across many model years, which simplifies part sourcing for older Rams. Limitations to note are fitment sensitivity and gasket fit; several users found the included rubber seal thinner than factory and needed to reuse the original O-ring or modify the gasket to stop small leaks. If you plan to install it yourself, have the original seal available or be prepared to fit a different gasket to ensure a proper housing seal.
Best for: Reliability-focused owners who want a straightforward, factory-style replacement thermostat for maintaining correct operating temperature in their Ram 3500 and prefer a part that matches original function.
Less Ideal for: Drivers unwilling to perform basic gasket swaps or those who need a guaranteed perfect seal without any fitment adjustments should consider a thermostat with a verified OEM-style gasket.
- Factory-style metal construction and 203°F opening temperature for correct operating control
- Wide compatibility across Chrysler, Dodge, Jeep and Ram V8 model years that simplifies part selection
- Supplied seal allows immediate installation without sourcing extra parts
- Simple, bolt-in replacement suitable for DIY installation
- Included rubber seal is reported thinner than factory and may not seat properly on some housings
- Some users needed to reuse the OEM O-ring or add a different gasket to stop minor leaks
Verdict: A practical, factory-style 203°F replacement thermostat that restores proper coolant regulation for Ram 3500 V8 engines when installed with a correct seal.
6. JXGZYD Engine Thermostat 52028898AE (203°F) for Ram 1500/2500/3500, Dodge, Chrysler, Jeep
| Manufacturer | JXGZYD |
|---|---|
| Model | JX-4 |
| Manufacturer Part Number | 52028898AE |
| Exterior | metal |
This JXGZYD thermostat is a metal-bodied, direct-replacement unit designed to restore correct coolant flow on affected Chrysler‑platform V8s. It installs into the factory housing and is intended to open at 203°F, which helps the engine reach and maintain normal operating temperature and can clear P0128 codes caused by a stuck-open thermostat. Typical use is a routine cooling-system repair during a thermostat service or when troubleshooting a coolant-temperature fault code. Notable features include a factory-style metal construction and a replacement part number listed to match 52028898AE. Practical benefits are straightforward fit-and-replace installation for many Ram, Dodge, Chrysler, and Jeep V8 models, and a simple way to return temperature control to spec without expensive shop labor. Limitations are mixed fit reports and a thin gasket included with the part, so reusing the vehicle's original gasket or confirming fit before final installation may be necessary.
Best for: Convenience-driven owners who want a ready-made replacement to fix temperature problems quickly without sourcing OEM parts or extensive troubleshooting.
Less Ideal for: Customers who need guaranteed exact-fit OEM parts for vehicles with known fitment quirks or who prefer dealership-sourced replacements should consider alternatives.
- Factory-style metal construction for durability and heat resistance
- Specified to open at 203°F to help the engine reach normal operating temperature
- Lists direct replacement part number 52028898AE for easier cross-reference
- Works as a quick, low-complexity repair to resolve coolant temperature faults
- Some buyers report fitment issues on specific model years despite the compatibility list
- Included gasket is thin and may be less durable than the original
Verdict: A budget-friendly, metal-bodied direct-replacement thermostat that restores proper coolant temperature control on many Chrysler V8 models.
7. MotoRad 7416-203 203°F Fail-Safe Thermostat
| Included Components | (1) Fail-Safe Thermostat, 203 °F |
|---|---|
| Voltage | 230 Volts |
| Power Source | Battery Powered |
| Temperature Control Type | thermostatic |
The MotoRad 7416-203 is a drop-in fail-safe thermostat designed to replace the factory unit in compatible Dodge, Chrysler, Jeep and Ram engines, including Ram 3500 models listed in the fitment. It is built with a locking feature intended to prevent coolant loss and catastrophic overheating by failing closed or holding a controlled position, and MotoRad states the part is tested and calibrated before shipping. Installation is the same as a factory replacement, so most home mechanics or professionals will fit it without modification. The thermostat is offered as a vehicle-specific fit and is advertised as manufactured to meet or exceed factory standards, which makes it a convenient option when you want a direct replacement. Buyer reports are mixed: many users report proper fit and reliable operation in Ram trucks while a minority report units that failed to open during testing. If you choose this part, bench-test it before installation and consider professional installation for peace of mind when avoiding engine risk.
Best for: Risk-averse mainstream buyers who want a direct, factory-style replacement for their Ram 3500 and prioritize a tested, drop-in part that minimizes installation complexity.
Less Ideal for: Buyers seeking adjustable or performance-tuned thermostats or those unwilling to bench-test parts before installation should consider other options.
- Vehicle-specific fit for affected Ram models makes installation straightforward
- Fail-safe, lockable design aimed at preventing coolant loss and engine damage
- Factory-quality manufacturing claims and pre-shipment calibration/testing
- Simple analog/button control and battery power means no vehicle reprogramming
- Some user reports of units failing to open during bench tests indicate inconsistent quality control
- Listed 203°F opening is fixed so it may not match every service preference
Verdict: A practical, vehicle-specific fail-safe replacement for Ram 3500 owners who want a factory-style thermostat but test units before installation due to occasional quality reports.
Choosing the Right Ram 3500 Thermostat: Key Factors to Consider
Correct Fitment and Mounting
Exact fitment to the Ram 3500 thermostat housing ensures the part seats properly and aligns with coolant passages. Mismatched dimensions or an incorrect flange can create sealing gaps, leading to leaks or erratic coolant flow. Proper mounting also affects thermostat orientation and bypass flow paths. Choosing a unit that matches the original mounting pattern reduces installation time and lowers the risk of introducing stress on the housing or hoses.
Opening Temperature and Thermal Response
The thermostat s specified opening temperature determines when coolant begins circulating through the radiator, so it directly influences engine warm-up time and operating temperature. A thermostat that opens too early can cause the engine to run cool, which affects efficiency and emissions, while one that opens too late increases overheating risk. Thermal response, or how consistently the valve opens and closes at its rated temperature, matters for stable temperature control during towing or idling. Look for thermostats with clearly stated temperature ratings and consistent actuation characteristics.
Seal Integrity and Gasket Compatibility
A reliable seal at the housing prevents coolant loss and maintains system pressure. The condition and compatibility of the thermostat housing seal or gasket influence long-term leak resistance, especially after repeated heat cycles or when using different coolant formulations. Choose thermostats that include or are compatible with high-quality gaskets, and ensure replacement seals match the housing design to avoid weeping or overtightening damage during installation.
Material Quality and Corrosion Resistance
Thermostat components are exposed to coolant and heat, so materials that resist corrosion and thermal fatigue extend service life. Brass, stainless steel, and coated steels are common in critical parts like the valve and spring, while housings may be metal or high-grade polymer. Better material quality reduces the chance of sticking, valve distortion, or structural failure when the engine is under heavy load or in harsh environmental conditions.
Bypass Flow Characteristics
Internal bypass ports help regulate coolant circulation before the thermostat fully opens, affecting warm-up behavior and head gasket protection. The size and design of the bypass path determine how much coolant recirculates through the engine versus being routed to the radiator at lower temperatures. Consider how bypass flow interacts with engine warm-up and heater core performance, especially if you tow or operate in cold climates where maintaining cabin heat quickly is important.
Ease of Installation and Serviceability
A thermostat that is straightforward to install reduces labor time and the chance of installation errors. Features that help include clear sealing surfaces, included gaskets, and design elements that aid alignment with the housing. Serviceability matters if you anticipate future inspections or repeated replacements. Thermostats that avoid overly tight torque requirements and that use standard fasteners make maintenance simpler for both DIYers and technicians.
How We Chose the Best Ram 3500 Thermostat
We focused on thermostats that specifically list compatibility with the Ram 3500 and meet factory-style fitment standards. Our selection criteria emphasized accurate fitment and mounting dimensions, consistent opening and closing temperatures, and reliable valve operation under load and varied ambient conditions. We also considered build quality of the housing and sealing surfaces, corrosion resistance of internal components, and availability of compatible gaskets or seals. We excluded universal or generic thermostats that require significant modification, units lacking clear temperature specifications, and parts without documented mechanical durability. Our approach prioritized parts that minimize installation hassle, restore correct thermal management, and reduce the chance of coolant leaks or premature failure.
Our full evaluation process is outlined in our review methodology.
FAQ
What are common signs of a failing thermostat in a Ram 3500?
Common signs include the engine overheating under load, the engine taking too long to reach normal operating temperature, or wide temperature gauge fluctuations. You might also notice poor cabin heat output or coolant leaks near the thermostat housing. These symptoms often point to a thermostat that is sticking closed, stuck open, or has a failed seal.
How do I test a thermostat without removing it?
You can observe coolant temperature behavior and heater performance while the engine warms up and idles. Rapid overheating, no warm-up, or a temperature gauge that stays unusually low often indicates thermostat issues. For a definitive test, many technicians monitor inlet and outlet hose temperatures or use a scan tool to read coolant temperature sensors while the engine reaches operating conditions.
Can a thermostat cause my engine to run cold or overheat?
Yes. A thermostat stuck open will allow continuous coolant flow and often causes the engine to run cooler than intended, while one stuck closed will prevent flow to the radiator and typically leads to overheating. Both conditions can affect performance and component longevity, so addressing thermostat faults promptly is important.
Should I replace the gasket or seal when changing the thermostat?
Replacing the thermostat housing gasket or seal during installation is usually recommended. Reusing an old seal can increase the risk of leaks, especially if the original material has compressed or been damaged during removal. New gaskets ensure a proper mating surface and help maintain system pressure.
How long does a thermostat typically last on a heavy-duty truck?
Thermostat lifespan varies with usage, coolant quality, and driving conditions. On heavy-duty trucks that tow or operate under high loads, thermostats often face greater thermal stress and may show issues sooner than passenger cars. Regular inspection during routine service helps catch early signs of sticking or leaks before they cause major problems.
Conclusion
When choosing a Ram 3500 thermostat, prioritize correct fitment, the proper opening temperature, and durable sealing to maintain reliable engine temperatures under load. Consider material quality and bypass design to match your typical driving and towing needs. Balancing thermal response with installation ease will reduce downtime and the chance of coolant leaks. Use the factors above to select a unit that restores stable temperature control and fits your service preferences.
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