Loading...

Lexus Gs300 Engine Coolant Thermostat Housing Assemblys

Lexus Gs300 Engine coolant thermostat housing assemblys

Starting at $21.95, AutoBuffy stocks 3 engine coolant thermostat housing assemblies from Beck/Arnley, SKP, and Aisin. The housing seals the thermostat to the engine and routes coolant through the system; a cracked, warped, or leaking housing causes coolant loss, overheating, and heater failure that can quickly escalate to serious engine damage if ignored.

Signs your Lexus Gs300 needs a new engine coolant thermostat housing assembly

  • Visible coolant puddle or wet stain directly beneath the thermostat housing on the engine block or intake
  • Coolant smell from the engine bay without a visible radiator or hose leak
  • Temperature gauge climbing toward the red zone or erratic needle movement during normal driving
  • Heater blowing cool or inconsistent air because coolant flow to the heater core is disrupted
  • Low coolant warning light or repeated need to top off the reservoir with no obvious external leak
  • White residue or mineral deposits crusted around the housing flange, indicating a slow ongoing seep

Which engine coolant thermostat housing assembly should you buy for your Lexus Gs300?

The main decision is whether to buy a bare housing, a housing pre-fitted with a new thermostat and gasket, or an OE-equivalent assembly that matches factory material and outlet position exactly. On many modern engines, the housing integrates the thermostat, temperature sensor port, and coolant hose connections into one unit, so replacing the whole assembly rather than individual pieces is often more reliable and cost-effective.

OEM-equivalent complete assembly
Best for
Owners who want a direct factory-match fit with no sourcing multiple pieces
What you get
Housing, integrated thermostat, gasket or O-ring, and sensor port — matches original material (plastic, aluminum, or magnesium alloy) and outlet angle
Housing + thermostat kit (aftermarket)
Best for
Budget-conscious repairs where the housing is intact but the thermostat has failed separately
What you get
Replacement thermostat calibrated to factory opening temperature paired with a compatible housing; may require purchasing a gasket separately
Heavy-duty aluminum housing
Best for
High-mileage vehicles or those in hot climates where OEM plastic housings have a history of cracking
What you get
Cast or billet aluminum construction that resists heat cycling and cracking better than plastic; may require adapting sensor and hose fittings
Housing with integrated coolant temperature sensor
Best for
Vehicles where the CTS mounts directly into the housing and the original sensor is corroded or damaged
What you get
All-in-one repair covering both the housing failure and a failing sensor in a single R&R, reducing labor time

Engine coolant thermostat housing assemblys brands we stock for your Lexus Gs300

Beck/Arnley
1 option · from $62.95
SKP
1 option · from $21.95
Aisin
1 option · from $57.95

Replacing an engine coolant thermostat housing assembly on a Lexus Gs300

Moderate⏱ 1–2 hoursSocket and ratchet setDrain pan for coolantFlat-blade screwdriver or housing gasket scraperPliers or hose clamp toolFunnel and fresh coolant for refill

Allow the engine to cool completely, then drain enough coolant from the radiator to bring the level below the housing before unbolting it and disconnecting any hose and sensor connections. Clean the mating surface on the engine block or intake thoroughly before installing the new housing with a fresh gasket or O-ring — do not reuse old sealing material. Refill and bleed the cooling system, then run the engine to operating temperature and inspect for leaks before returning the vehicle to service.

Frequently asked questions

How much does it cost to replace engine coolant thermostat housing assemblies on a Lexus Gs300?
Parts start at $21.95 at AutoBuffy. A complete DIY repair using a quality aftermarket or OEM-equivalent assembly typically falls within a modest range depending on brand and whether the kit includes the thermostat and gasket. Adding professional labor at a shop will increase the total, but the part itself is straightforward to source.
Can I drive my Lexus Gs300 with a leaking thermostat housing?
No — even a slow leak is unsafe to drive with for long. Coolant loss lowers system pressure and can cause the engine to overheat within miles. A cracked or leaking thermostat housing on a Lexus Gs300 should be treated as an urgent repair to prevent warped cylinder heads or worse engine damage.
Is it better to replace just the gasket or the entire thermostat housing assembly on a Lexus Gs300?
If the housing body is cracked, warped, or corroded, replace the full assembly — a new gasket will not seal against a damaged mating surface. If the housing is structurally sound and the leak is clearly from a failed gasket or O-ring only, replacing the seal alone is acceptable and less expensive.
Does replacing the thermostat housing on a Lexus Gs300 require bleeding the cooling system?
Yes. Any time the cooling system is opened on a Lexus Gs300, air can enter the system. After installation, the system must be bled — typically by running the engine with the heater on full and allowing the thermostat to open — to purge air pockets that cause overheating or heater malfunctions.
How long does a thermostat housing assembly last on a Lexus Gs300?
Plastic housings on a Lexus Gs300 typically last many years but are more prone to cracking from heat cycling as mileage climbs. Aluminum or metal housings tend to last the life of the engine barring physical damage. The gasket or O-ring usually fails before the housing itself and can often be replaced independently.
Will a faulty thermostat housing cause a check engine light on a Lexus Gs300?
It can. If the housing failure disrupts coolant flow enough to affect engine temperature regulation, the ECU may set a coolant temperature-related fault code. Additionally, if the housing incorporates a coolant temperature sensor port and that sensor is disturbed or damaged during a leak, a sensor fault code may also appear.

Shop engine coolant thermostat housing assemblys by year for the Lexus Gs300

2006

More parts for your Lexus Gs300

Side Marker Light AssemblyHeadlight Wiring HarnessEngine Crankshaft SealVacuum Regulator ValveTire Pressure Monitoring System (TPMS) Programmable SensorCV Joint BootA/C System Valve Core and Cap KitTie Rod End Set

Engine coolant thermostat housing assemblys for other Lexus models

Lexus LC500hLexus IS FLexus CT200hLexus GS460Lexus GX460Lexus IS350