How to remove and install the thermostat housing on Mazda 3?

To replace the thermostat assembly, initially, one has to detach the cable on the negative terminal of the battery by lifting up the battery cover. Lift the car on jackstands and take off the splash covers. Drain the cooling system, preserve the coolant in case it is in good condition. Get the coolant expansion tank out of the way and then unhook the drivebelt(s) and either the drivebelt tensioner or idler pulley based on the type of engine. Follow the lower radiator hose to the engine until you find the thermostat housing. Unscrew the hose clamps and loosen the bypass hose and lower radiator hose out of the housing, and use adjustable pliers to loosen the seal, if it is necessary. In case the cover of the thermostat housing is corroded or pitted, then change. Take out the bolts of the thermostat housing and unscrew the housing, but be careful that the thermostat is a part of the housing and cannot be taken out. To install, wipe off the sealing areas and examine the hoses and replace them as necessary. Install a new gasket of type O-ring in the housing groove and the thermostat housing can be installed by screwing on bolts to the required torque. Add the cooling system, then turn on the engine, get the engine up to a normal working temperature and examine any leaks and check the thermostat functionality.

Genuine Mazda 3 Thermostat

Engine Coolant Thermostat

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Mazda 3 Thermostat Part Number: P502-15-171
$23.89 MSRP: $31.85
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Product Specifications
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2021-2024 Mazda 3 | 2.5 Carbon Turbo, 2.5 Turbo, 2.5 Turbo Premium Plus | 4 Cyl 2.5 L GAS
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Mazda 3 Thermostat Part Number: PE01-15-171
$28.34 MSRP: $37.79
You Save: $9.45 (26%)
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Product Specifications
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2012-2018 Mazda 3 | Grand Touring, i, i Grand Touring, I Sport, i SV, I Touring, Mazdaspeed, S, s Grand Touring, s Touring, Sport, Touring | 4 Cyl 2.0 L GAS, 4 Cyl 2.3 L GAS, 4 Cyl 2.5 L GAS
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Mazda 3 Thermostat Part Number: P501-15-171
$28.40 MSRP: $37.87
You Save: $9.47 (26%)
Ships in 1-2 Business Days
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Product Specifications
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2018 Mazda 3 | Grand Touring, Sport, Touring | 4 Cyl 2.0 L GAS, 4 Cyl 2.5 L GAS
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Mazda 3 Thermostat Part Number: L336-15-170
$42.59 MSRP: $56.79
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Product Specifications
- Other Name: Thermostat & Cover; Cover, Thermostat, Thermostat Housing, Water Inlet
- Replaces: L328-15-170A, L327-15-170, L327-15-170A, L327-15-171, L328-15-170B, ZZCA-15-172, ZZCA-15-172A, LFE2-15-170
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2007-2013 Mazda 3 | Mazdaspeed, S | 4 Cyl 2.3 L GAS, 4 Cyl 2.5 L GAS

Mazda 3 Thermostat

The Mazda 3 Thermostat ensures that the engine does not exceed its optimal temperature zone, ensuring performance is preserved and that excessive heat does not cause harm to the engine during each run. Placed next to the radiator, the device acts like a closed-loop control unit, detecting the warmth of the coolant and blocking or releasing the flow accordingly so that the motor does not overheat or run too cool. There have been two basic styles that have emerged throughout the history of the Mazda car line. The first heat regulator was a mechanical wax-pellet Thermostat, which was identical to the successful bimetal system originally perfected in the nineteenth century, wherein the expansion of the wax opens a valve when the coolant reaches a certain temperature and then closes it when it becomes colder. Subsequent models applied an electronically controlled unit that operates in the same way but adds a digital sensor and control signal, similar in simplicity to modern programmable home Thermostats. The primary distinction is the response speed and accuracy. The electronic unit can adjust the position of valves more frequently, and this helps the cooling system stabilize more quickly, increase fuel efficiency and reduce emissions. In whatever form your Mazda might have, the basic objective is the same rapid warming after start-up and then constant regulation after cruising, and this is achieved by each Thermostat automatically. Car owners of Mazda 3 cars enjoy this reliability without input from the driver. The straightforward, long-lived construction is advantageous to drivers, as well as the centuries of evolution in a single component of the Thermostat.

Looking for Thermostat with proven quality? Choose OEM Thermostat. Mazda designs and builds them to strict factory specs. Every piece goes through rigorous quality checks. You'll get parts that fit right and work like new. Shop our huge inventory of OEM Mazda 3 parts. Enjoy the highly competitive prices online. Our site is your one-stop shop. Each genuine 3 part includes a manufacturer's warranty. Buy with confidence. Our return policy is simple and hassle-free. In a rush? Choose expedited delivery at checkout. You'll love the streamlined experience from search to checkout to receiving your order.

Mazda 3 Thermostat Parts and Q&A

Thermostat
L336-15-170
Q: How to remove and install the thermostat housing on Mazda 3?
A:
To replace the thermostat assembly, initially, one has to detach the cable on the negative terminal of the battery by lifting up the battery cover. Lift the car on jackstands and take off the splash covers. Drain the cooling system, preserve the coolant in case it is in good condition. Get the coolant expansion tank out of the way and then unhook the drivebelt(s) and either the drivebelt tensioner or idler pulley based on the type of engine. Follow the lower radiator hose to the engine until you find the thermostat housing. Unscrew the hose clamps and loosen the bypass hose and lower radiator hose out of the housing, and use adjustable pliers to loosen the seal, if it is necessary. In case the cover of the thermostat housing is corroded or pitted, then change. Take out the bolts of the thermostat housing and unscrew the housing, but be careful that the thermostat is a part of the housing and cannot be taken out. To install, wipe off the sealing areas and examine the hoses and replace them as necessary. Install a new gasket of type O-ring in the housing groove and the thermostat housing can be installed by screwing on bolts to the required torque. Add the cooling system, then turn on the engine, get the engine up to a normal working temperature and examine any leaks and check the thermostat functionality.