Where is the thermostat on a 2008 Lexus RX 350?

The thermostat for this model is inside the engine’s thermostat housing, at the end of the coolant outlet where the upper radiator hose meets the engine. In the 2008 RX 350 with the 3.5L V6 (2GR-FE), you won’t find a separate unit in the radiator; the thermostat regulates coolant flow from within that housing on the engine, typically toward the passenger side near the firewall.

Where to look and how it works

The thermostat sits inside the housing that covers the end of the engine’s coolant outlet. It opens and closes to control when coolant flows from the engine to the radiator. This arrangement is common across Toyota and Lexus 3.5L V6 installations and helps maintain steady engine temperature.

Safety reminder: always let the engine cool completely before touching hoses or the housing, and use the proper tools and a catch pan for any coolant spills.

To locate the thermostat housing on a 2008 RX 350, follow these practical steps:

1. Open the hood and let the engine cool completely to avoid burns from hot coolant or pressurized hoses.


2. Find the large upper radiator hose that runs toward the engine; trace it to the point where it attaches to the engine block. That connection marks the coolant outlet.


3. Inspect the area around the outlet for a plastic or metal housing with bolts and possibly a coolant temperature sensor plugged into it. This is the thermostat housing, and the thermostat sits inside.


4. Note the gasket or O‑ring around the housing; if you plan a replacement, you’ll want to replace the gasket and reseal the housing.

Locating and confirming the thermostat housing helps you perform diagnostics for overheating, leaks, or slow warming up.

Replacing the thermostat: steps and tips

If replacement is required or you’re performing a routine inspection, use this guide to proceed carefully.

Tools and safety

• Socket set and screwdrivers


• Wrenches and pliers


• New thermostat and gasket or O‑ring


• Coolant (and a catch pan)


• Torque wrench and rags/solvent for cleaning the mating surfaces


• Safety gloves and eye protection

With the right tools and precautions, you can replace the thermostat and restore proper coolant flow.

1. Disconnect the negative battery terminal to avoid electrical issues while you work near cooling system components.


2. Drain a portion of the coolant so you can safely detach the thermostat housing and hose without excessive spillage.


3. Loosen and remove the hose clamp on the upper radiator hose and detach the hose from the thermostat housing.


4. Remove the bolts securing the thermostat housing to the engine, then carefully lift off the housing to expose the thermostat inside the coolant outlet.


5. Remove the old thermostat and clean the mating surfaces. Install the new thermostat in the correct orientation (spring side toward the engine) and reseal with a new gasket or O‑ring.


6. Reattach the thermostat housing, reconnect hoses, and tighten the bolts to the recommended torque.


7. Refill the cooling system with the proper mix, then start the engine with the radiator cap off to bleed air. Check for leaks and add coolant as needed once the system stabilizes.

If overheating issues persist after replacement, or you notice persistent leaks, consider professional service for a thorough diagnosis.

Summary

In short, on a 2008 Lexus RX 350 the thermostat is housed inside the thermostat housing at the end of the engine’s coolant outlet where the upper radiator hose attaches. Locating it involves following the upper hose to the engine and identifying the housing, then opening and inspecting the housing if you need to replace the thermostat. Proper cooling-system bleeding and careful resealing are essential after any work. When in doubt, a professional mechanic can perform the service with factory torque specs and correct coolant type.

What is the most common problem with Lexus RX350?

The most common problem with the Lexus RX 350 is a massive oil leak, specifically from the VVT-i oil line, which can lead to rapid oil loss and potential engine failure, especially in older models like the 2010. Other frequent issues include faulty rain sensors, especially in newer models, resulting in wipers that malfunction randomly. Older model years (2007 and 2010) also show a tendency for airbag warning lights and transmission problems, while some 2016 models experienced rough shifting and transmission issues.
 
This video discusses the 2013 Lexus RX 350's common problems, including oil leaks and other issues: 55scar PROblemsYouTube · Jun 26, 2022
Engine and oil leaks 

• VVT-i oil line leak: This is a recurring issue, particularly in older models like the 2010, where the oil line can burst, causing significant oil loss and potential engine damage if not addressed immediately. 
• Check Engine light: This can be triggered by various engine issues, including problems with the variable valve timing system. 

Electrical and sensor problems 

• Rain sensor malfunction: Both older and newer models have reported issues with the rain-sensing wipers not functioning correctly or stopping randomly. 
• Airbag warning light: This has been reported across several model years, often linked to codes B0111 and B0116 due to issues like faulty sensors or a depleted airbag backup battery. 
• Infotainment system issues: Problems like malfunctioning touchscreens, unresponsive climate controls, and other glitches have been reported, particularly in recent years. 

Transmission and drivetrain issues

• Rough shifting: Some models, such as the 2016, have been reported to have delayed gear shifts and a lack of smoothness.
• Transmission failure: In the 2016 model year, transmission problems were significant enough to cause concerns about long-term reliability. 

Other potential problems

• Spontaneously shattering sunroofs: Though rare, this has been reported in some model years and is a significant safety concern. 
• Body integrity issues: Some older models, such as the 2010, have experienced body-related issues like rattling doors. 
• Steering mechanism leaks: These can be costly to repair. 

Where is the thermostat located on a Lexus?

There or feel around there is a there's a hose that a a hard pipe that comes from the side. And comes right over here to this uh lower radiator hose.

Where is the thermostat located on a 2008 Lexus ES 350?

The 2008 Lexus ES 350 thermostat is located on the engine block, connected to the lower radiator hose. You can find it by following the lower radiator hose back to where it connects to a pipe on the engine. It's housed in a small metal component that is usually secured by three 10mm nuts.
 
This video shows the location of the thermostat housing on a similar Lexus V6 engine: 56sHelping Hand Auto RepairYouTube · Jun 14, 2020

• Location: Find the lower radiator hose and follow it to where it connects to the engine block. This connection point is where the thermostat is located, within a housing that is part of the engine's coolant inlet pipe. 
• Appearance: The housing is typically a small aluminum piece secured by bolts or nuts. You may need to move electrical connectors and wiring harnesses out of the way to get to it. 
• Access: Accessing the thermostat on the 2008 ES 350 requires removing the serpentine belt and the front engine mount bracket to get enough clearance, according to Lexus Parts Now. 
• Removal: Once the housing is accessible, you will need to disconnect the lower radiator hose, then remove the three 10mm nuts to pull off the housing and get to the thermostat and its gasket. 

This video shows the steps to replace the serpentine belt and access the thermostat housing on a similar Lexus ES 350: 1mRichierock1YouTube · Jan 25, 2023

How much does it cost to replace a thermostat in a 2007 Lexus RX350?

The average cost for a Lexus RX350 Thermostat Replacement is between $673 and $907. Labor costs are estimated between $503 and $738 while parts are typically priced around $170. This range does not include taxes and fees, and does not factor in your unique location. Related repairs may also be needed.