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If your Acura TSX is showing temperature swings or taking too long to warm up, choosing the right thermostat matters for engine health and drivability. The correct thermostat helps maintain optimal operating temperature, reduces wear, and can prevent overheating or running too cold. This guide covers seven shortlisted thermostats that fit the Acura TSX and highlights the factors we used to evaluate them, including fitment reliability and temperature response. Read on for practical guidance before you proceed with replacement or diagnostics.
Looking for other parts? See all Acura TSX parts & accessories.
Top Picks at a Glance
| Best Reviewed A top-rated pick with lots of positive feedback | AISIN THH-003 Engine Coolant Thermostat with Housing and Gasket |  |
| Most Popular A crowd favorite that many people choose with confidence | Gates 33914 Engine Coolant Thermostat |  |
| Best Quality Built to a higher standard if you want something more solid | Honda Thermostat Assembly 19301-RAF-004 (Genuine) |  |
| Best Budget The cheapest option that still gets the job done reliably | BRTEC Engine Coolant Thermostat Assembly (fits 19301RAAA02) |  |
| Most Sold A high-volume bestseller chosen again and again | MotoRad 456-160 Engine Coolant Thermostat for 8-Cylinder GM |  |
| Best Value for Money The sweet spot between price and what you get | IRONTEK Engine Coolant Thermostat Housing Assembly |  |
| Best Overall The best all-around choice for most situations | Gates 34198 Engine Coolant Thermostat |  |
1. AISIN THH-003 Engine Coolant Thermostat with Housing and Gasket
| Manufacturer Part Number | THH-003 |
|---|---|
| OEM Part Number | 19301-RAF-004 |
| Position | Center |
| Exterior | Machined |
The AISIN THH-003 replaces the engine coolant thermostat and comes as a complete assembly with housing and gasket, so you can swap the entire unit without hunting for additional parts. It installs like a factory component and is intended to open at the correct OEM-specified temperature, helping the cooling system reach and maintain optimal operating temperature. In typical use it directly replaces the original thermostat on compatible Acura TSX models and is useful during routine cooling-system service or when diagnosing temperature control problems. Notable features include machined exterior finish and OEM-matched form, fit, and function claims that simplify fitment and reduce the risk of leaks. Practical benefits are straightforward installation and dependable temperature regulation that can prevent overheating or excessive warm-up time. Limitations are that mounting hardware is not always included, so you may need replacement bolts if originals are corroded, and a few shoppers prefer dealer-branded parts despite the similar construction.
Best for: Reliability-focused buyers who prioritize a factory-quality replacement that restores intended temperature control and reduces repeat repairs on their Acura TSX.
Less Ideal for: Shoppers who want a dealer-branded Acura part for warranty or branding reasons, or those who prefer a kit that includes all fasteners and hardware out of the box.
- Complete assembly with thermostat, housing, and gasket reduces parts sourcing and simplifies installation.
- Manufactured to match factory-specified operating temperature for consistent engine warm-up and cooling.
- Machined exterior and OEM-level construction for a durable, long-lasting replacement.
- Widely reported exact fit for Acura TSX applications, minimizing adjustment or trimming.
- Mounting bolts are not included, so corroded fasteners may need replacement before installation.
- Some buyers prefer dealer-branded parts and may opt for a branded Acura thermostat instead.
Verdict Aisin's THH-003 is a dependable, factory-matched thermostat assembly that restores proper temperature control on Acura TSX models, but order replacement mounting bolts if yours are corroded.
2. Gates 33914 Engine Coolant Thermostat
| Manufacturer | Gates |
|---|---|
| Voltage | 12 Volts |
| Material | Metal |
| Manufacturer Part Number | 33914 |
This Gates 33914 is a straightforward replacement thermostat that opens at a lower-than-factory temperature to regulate coolant flow and help the engine reach and hold operating temperature. It installs inline in the cooling system and is typically used during routine thermostat replacement on vehicles that accept this part. The unit is metal-bodied and described as factory-calibrated so opening and closing temperatures remain consistent under pressure changes, which helps prevent overheating or overcooling in normal driving. Practical benefits include simple mechanical operation, compatibility with vehicles that use the 33914 fitment, and a rugged machined exterior that resists corrosion. Important limitations are that the listing and some user reports note the gasket may not be included, so you may need to source a seal separately, and a few buyers have reported receiving an aftermarket variant rather than Gates-branded packaging, which could affect longevity. Check compatibility for the Acura TSX model year before purchase and plan to have a gasket on hand for installation.
Best for: Buyers who prioritize convenience and straightforward maintenance for their Acura TSX and want a ready replacement part that gets the cooling system back to service quickly.
Less Ideal for: Drivers seeking an exact factory-spec temperature curve or a complete installation kit with seals should consider alternatives or source the correct gasket and verify brand authenticity before installing.
- Factory-calibrated piston for consistent opening and closing under pressure
- Sturdy machined metal construction for durability
- Simple inline design that is easy for routine thermostat replacement
- Gasket not consistently included with the unit
- Some reports of aftermarket units sold in Gates packaging, creating quality uncertainty
Verdict A durable, factory-calibrated replacement thermostat suited for quick, convenience-focused swaps on Acura TSX models provided you confirm fitment and supply the seal separately.
3. Honda Thermostat Assembly 19301-RAF-004 (Genuine)
| Brand | Honda |
|---|---|
| Model | Genuine Honda THERMOSTAT ASSY- |
| Manufacturer Part Number | 19301-RAF-004 |
This genuine Honda thermostat assembly replaces a failing thermostat to restore correct engine warm-up and coolant flow in compatible Acura TSX engines. It installs in the same location as the original and functions like a factory replacement, opening at the specified temperature to allow coolant circulation and closing as the engine cools. The main benefit is faithful fit and operation compared with aftermarket units, which helps maintain expected idle warm-up, heater performance, and engine temperature control. Using a factory-quality thermostat reduces the risk of incorrect opening temperature or uneven flow that can cause overheating or poor cabin heat. Drawbacks are limited to the narrow scope of the part: it only replaces the thermostat itself, so you may still need a gasket or housing inspection and any associated seals when doing the job. Also this is a direct replacement for specific engine setups and will not be a universal fit across all model years without checking compatibility.
Best for: Performance-oriented buyers who prioritize factory-quality components to maintain precise engine temperature control and reliable thermal behavior in their Acura TSX.
Less Ideal for: Buyers seeking a low-cost universal aftermarket option or a multi-year one-size-fits-all solution should consider alternatives instead.
- Genuine factory-quality part for consistent opening temperature and reliable operation
- Direct fit replacement for compatible Honda/Acura cooling systems to simplify installation
- Helps restore proper heater output and engine warm-up behavior compared with worn thermostats
- Replaces only the thermostat so additional seals or housing work may be needed during installation
- Compatibility varies by year and engine, so vehicle fitment must be verified before purchase
Verdict Choose this genuine Honda thermostat when you want a factory-quality replacement to keep an Acura TSX running at the correct operating temperature.
4. BRTEC Engine Coolant Thermostat Assembly (fits 19301RAAA02)
| Brand | BRTEC |
|---|---|
| Manufacturer Part Number | BCTMH8095 |
| Vehicle fitment | Acura 2009–2014 TSX; Honda 2003–2012 Accord; 2012–2015 Crosstour; 2003–2011 Element |
| Item Weight | 8.3 ounces |
This BRTEC thermostat assembly replaces the factory thermostat housing and valve to restore proper coolant flow and engine temperature regulation on compatible Acura TSX and Honda models. It is intended as a direct replacement for part number 19301-RAA-A02 and installs in place of the original unit to eliminate overheating or extended warm-up issues. The product emphasizes ease of installation and durability, with manufacturer testing claimed to improve long-term performance. For a budget-focused repair it offers clear cost savings compared with dealer parts and comes with basic installation guidance. However, fitment must be verified against the original part before purchase and some users report occasional premature failures, so expect variability in longevity compared with higher-end factory-quality parts. This unit is best used for routine thermostat replacements where cost and quick repair are priorities rather than a long-term performance upgrade.
Best for: Budget-conscious buyers who need an affordable, quick replacement to get their Acura TSX back to normal operation without paying dealer prices.
Less Ideal for: Drivers seeking a long-term, high-reliability factory-quality part or those unwilling to verify fitment and inspect the unit after installation should consider OEM or premium alternatives.
- Direct replacement for part number 19301-RAA-A02 for straightforward fit on listed vehicles
- Low-cost option that can significantly reduce repair expense versus dealer parts
- Marketed as easy to install which helps DIY repairs without specialized tools
- Manufacturer states units undergo wear testing to improve durability
- Some customers report early failures or coolant leaks on certain installations
- Quality and longevity may vary compared with factory-quality thermostat housings
Verdict A cost-effective direct-replacement thermostat assembly for Acura TSX owners who prioritize low repair cost and quick DIY replacement, with some risk of variable longevity.
5. MotoRad 456-160 Engine Coolant Thermostat for 8-Cylinder GM
| Brand | MotoRad |
|---|---|
| Model Name | 456-160 |
| Temperature Control Type | Thermostatic |
| Specification Met | OEM |
The MotoRad 456-160 is a direct-replacement thermostatic valve intended to control coolant flow and maintain stable operating temperatures in compatible 8-cylinder GM engines. It installs in place of a factory thermostat and works the same way as a factory-quality unit: opening at its set temperature to allow coolant circulation and closing when the engine cools. Buyers report noticeable temperature drops in daily driving and highway use, which helps engine longevity and air conditioning performance in hot conditions. The part is marketed as meeting OEM specification and customers find it straightforward to fit where listed. Limitations: compatibility is restricted to many GM models and years rather than Acura vehicles, so fitment must be verified before purchase, and some users noted fit issues on certain engine variants. There is no indication of adjustable calibration or enhanced performance beyond cooler running compared with some stock thermostats, so it is best used as a like-for-like factory replacement rather than a performance modification.
Best for: Risk-averse mainstream buyers looking for a factory-style, straightforward replacement thermostat that restores proper cooling behavior without experimentation.
Less Ideal for: Drivers seeking a thermostat specifically for an Acura TSX or those wanting an adjustable or performance-grade thermostat should look for parts explicitly listed for that vehicle or designed for performance tuning.
- Designed as a direct replacement for specified 8-cylinder GM engines
- Meets OEM specification for fit and function according to the product listing
- Reported to lower operating temperatures in real-world driving, improving cooling in traffic and on long drives
- Not listed for Acura TSX or non-GM fitment so not suitable without confirmed compatibility
- No adjustable set point or performance tuning options
- Some users reported fitment problems on select engine years or variants
Verdict A solid factory-style replacement for the GM 8-cylinder applications listed, but not appropriate if you need a thermostat specifically for an Acura TSX.
6. IRONTEK Engine Coolant Thermostat Housing Assembly
| Manufacturer | IRONTEK |
|---|---|
| Manufacturer Part Number | IRKTMH8044 |
| Vehicle Fitment | 2004-2008 Acura TSX Base Sedan 4-Door |
| Interchange Part Numbers | 902-788, 19301-RAF-003, 19301-RAF-004 |
This IRONTEK thermostat housing assembly replaces the factory housing on compatible Acura TSX models and restores the coolant path, thermostat mounting, and sensor connections in one unit. It is intended for do-it-yourself or shop replacement when the original housing leaks, cracks, or the thermostat fails. The part is molded to match the original mounting points so installation is straightforward and typically requires only basic hand tools and a brief coolant drain. Notable features include claimed precision engineering to match factory fitment and included interchange numbers for verification against OEM parts. Practical benefits are low cost compared with dealer parts and the convenience of getting the housing and thermostat interface in a single component. Limitations to be aware of are that some customers report brittle plastic connectors and occasional need to trim or supply seals during install, so careful handling and a fresh gasket or sealant may be required for a leak-free result. Verify exact fitment for your TSX before installation.
Best for: Practical optimizers who prioritize repairing an Acura TSX affordably and prefer a cost-effective, functional replacement that gets the cooling system back to working order without premium dealer pricing.
Less Ideal for: If you want the absolute highest-end factory refinish or prefer parts guaranteed to include every OEM gasket and clip, consider sourcing a factory-quality replacement or a dealer part instead.
- Direct-replacement design intended to match factory mounting and thermostat location.
- Budget-friendly alternative to dealer parts, lowering repair cost.
- Ships as a complete housing assembly so thermostat and sensor ports are in place for quick swap.
- Manufacturer provides 36-month after-sales service (one-time replacement).
- Some review reports describe injection-molded parts or electrical connectors that can be fragile during installation.
- May require cutting or adding seals rather than providing ready-to-install gaskets in every case.
Verdict A cost-conscious, ready-to-install housing assembly for Acura TSX owners who want a practical, budget-friendly replacement rather than an OEM dealer part.
7. Gates 34198 Engine Coolant Thermostat
| Brand | Gates |
|---|---|
| Model | 34198 |
| Position | Center |
| Exterior | Machined |
This Gates 34198 thermostat replaces the factory unit to restore proper coolant flow and temperature control in vehicles where it fits, and for an Acura TSX it is intended to match factory fit and function. It installs in place of the original thermostat and uses factory-style seals and jiggle pins to vent trapped air, which helps prevent hot spots and poor warm-up behavior. The calibrated valve opens and closes reliably under changing pressure so the engine reaches and maintains proper operating temperature. For routine maintenance or thermostat failure, this part offers straightforward, one-to-one replacement with no modification required when compatible. Limitations are that it must match the TSX application number exactly and installation requires basic cooling-system work including draining and refilling coolant; it does not include hoses or a gasket beyond the supplied seal where applicable. If your TSX needs a direct factory-quality replacement, this is a practical choice, but verify fitment for your model year before ordering.
Best for: Balanced buyers who want a reliable, factory-quality replacement part that restores correct engine temperature behavior without aftermarket modifications.
Less Ideal for: Drivers looking for performance thermostats with altered opening temperatures or those who prefer a full cooling-system overhaul including hoses and fittings.
- Factory-equivalent fit and calibration for direct replacement when matched to the correct application
- Includes jiggle pin design to help purge air and improve warm-up consistency
- Machined exterior and factory-style seals for leak-free installation
- Trusted aftermarket brand with a long track record in cooling parts
- Requires coolant drain and refill during installation which adds labor and mess
- Not a universal part so fitment must be confirmed for the specific TSX model year
Verdict A dependable, factory-style replacement thermostat for TSX owners who need a direct-fit part to restore proper cooling performance.
Choosing the Right Acura TSX Thermostat: Key Factors to Consider
Correct Fitment and Ports
Correct mechanical fitment ensures the thermostat seats properly and that inlet and outlet ports align with the housing and hoses. A precise fit reduces the chance of leaks and ensures the unit operates as intended under pressure and temperature cycles.
When fitment is wrong you may see persistent leaks, poor coolant circulation, or difficulty installing the part. Check flange shape, bolt pattern, and sensor or bypass connections to avoid surprises during replacement.
Opening Temperature and Tolerance
The thermostat opening temperature determines when coolant flow begins and directly affects engine operating temperature. Choosing a unit with the correct specified opening point and a tight tolerance helps maintain stable thermostat control and proper cabin heating performance.
If the opening temperature is too low the engine can run cold, reducing efficiency. If it is too high or inconsistent the engine can overheat. Prefer thermostats that list a clear opening temperature and have minimal variance.
Seal and Gasket Quality
High-quality seals and gaskets prevent coolant leakage at the thermostat housing under thermal cycling. Materials that resist compression set and coolant additives extend service life and reduce the chance of slow leaks that are hard to diagnose.
Consider units that include a proper gasket or O-ring made from durable materials and those designed to mate cleanly with the housing to avoid repeat service for seal failures.
Build Materials and Corrosion Resistance
Materials used for the valve, frame, and spring affect durability in a hot, corrosive coolant environment. Corrosion-resistant metals or coated components maintain movement reliability and prevent sticking over time.
Inferior materials can lead to rust, binding, or weakened springs that alter opening characteristics. Look for thermostats specified for automotive coolant exposure and that use durable coatings or stainless components where appropriate.
Valve Mechanism and Response Consistency
The design of the valve and its thermal element controls how smoothly and predictably the thermostat responds to temperature changes. A consistent response avoids sudden temperature swings and helps the engine reach and hold its target temperature.
Poorly designed mechanisms can stick open or closed intermittently, causing overheating or prolonged warm-up. Prioritize designs with proven thermal elements and consistent movement through many cycles.
Installation Ease and Instructions
Clear instructions and straightforward installation reduce installation errors that can cause leaks or incorrect operation. Features like integrated gaskets or matching bolt patterns speed up replacement and reduce the likelihood of improper sealing.
If you plan DIY installation, check for included hardware, torque specifications, and any vehicle-specific notes to ensure a smooth swap and correct reassembly of hoses and housing components.
FAQ
What are common signs of a bad thermostat in an Acura TSX?
Common signs include the engine overheating intermittently, the temperature gauge rising quickly, or the engine taking a long time to reach normal operating temperature. You might also notice erratic temperature gauge behavior or inconsistent cabin heat. These symptoms often indicate the thermostat is sticking closed or open, though other cooling system issues can cause similar behavior.
How do I test a thermostat without removing it?
You can first observe temperature behavior after a cold start and while the engine warms up; if the temperature jumps erratically or never reaches normal range that is informative. For a direct test some technicians use an infrared thermometer on the upper radiator hose to watch for a sudden rise in temperature when the thermostat opens. These checks can suggest a sticking thermostat but do not replace a bench test or visual inspection when removed.
Can a thermostat cause my engine to overheat?
Yes. If the thermostat sticks closed it prevents proper coolant circulation and can cause the engine to overheat fairly quickly. However, overheating can also stem from low coolant level, radiator blockage, water pump failure, or cooling fan problems, so diagnose multiple systems rather than assuming the thermostat alone.
How likely is a thermostat housing seal leak and what should I watch for?
Housing seal leaks are a common service issue because the housing experiences thermal cycling and mechanical stress. Look for small coolant drips at the housing seam, dried coolant residue, or a steady loss of coolant without external hose leaks. Replacing the gasket or seal with a matched part and following correct torque specs usually resolves the issue.
Should I replace the thermostat when I replace the water pump?
Often replacing the thermostat during related cooling system service is recommended because the components share the same service life and access. Doing both at once reduces future labor and the risk of repeated coolant system disassembly, though the decision depends on the condition and age of the existing thermostat.
What affects the cost of thermostat replacement?
Cost drivers include the part quality, whether the housing or gasket must also be replaced, and labor complexity due to routing hoses or removing ancillary components. Accessibility on the Acura TSX and any related drain and refill work for the coolant will also affect total service time and cost.
How We Chose the Best Acura TSX Thermostat
We focused on parts that specifically fit the Acura TSX and that meet the OEM temperature range and mechanical specifications. Primary evaluation criteria included exact fitment to the vehicle mounting and ports, the thermostat opening temperature and tolerance, and build quality of the valve and spring. We also considered housing and gasket compatibility, resistance to corrosion, and the quality of seals to reduce risk of leaks. Ease of installation and clear instructions were included as practical factors for DIY installers and technicians. Finally we reviewed reported longevity and failure modes to prioritize units that maintain consistent temperature control over time. We excluded universal or ambiguous-fit thermostats that require significant modification and any units lacking clear vehicle fitment data. We did not consider unrelated accessories or parts that do not affect temperature regulation directly, such as external sensors or unrelated cooling system components.
Our full evaluation process is outlined in our review methodology.
Conclusion
When replacing an Acura TSX thermostat prioritize correct vehicle fitment, the specified opening temperature, and reliable seals. Those factors most directly affect engine temperature stability, heater performance, and the risk of leaks. Balance durability and ease of installation against the service you can perform. Addressing related cooling system items, such as hoses and housing seals, at the same time can reduce the chance of repeat work and help maintain consistent engine operating temperature.
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