How to drain and clean the coolant reservoir on Mazda 3?

Empty the cooling system until the reservoir is emptied. When provided with the original hose clamps, have them remove the clamps of the smaller hoses with the pliers and also disconnect the hoses to the reservoir. Take off the screw attaching the reservoir to the inner fender panel. Pick up the tank and detach it at the front mounting tab and unhook the hose on the bottom of the tank. Use soapy water and brush to clean out the tank and make sure that inside the tank no deposits have been left, also check the reservoir well and in case there is a crack then change the reservoir. Removal is the other side of installation after which the cooling system is filled.

Genuine Mazda 3 Coolant Reservoir

Coolant Tank Reservoir

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9 Coolant Reservoirs found

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Mazda 3 Expansion Tank Part Number: PAF3-15-351
$7.59 MSRP: $10.12
You Save: $2.53 (25%)
Ships in 1-2 Business Days
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Product Specifications
- Other Name: Tank, Sub-Radiator; Expansion Tank, Reservoir Tank
- Replaces: PAF1-15-351
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2019-2024 Mazda 3 | 2.0, 2.5 S, 2.5 Turbo, 2.5 Turbo Premium Plus, Base, Carbon Edition, Preferred, Premium, Select, Select Sport | 4 Cyl 2.0 L GAS, 4 Cyl 2.5 L GAS
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Mazda 3 Reservoir Part Number: PE01-15-351A
$30.04 MSRP: $40.07
You Save: $10.03 (26%)
Ships in 1-2 Business Days
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Product Specifications
- Other Name: Tank, Sub-Radiator; Reservoir, Reservoir Tank
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2014-2018 Mazda 3 | Grand Touring, i Grand Touring, I Sport, i SV, I Touring, s Grand Touring, s Touring, Sport, Touring | 4 Cyl 2.0 L GAS, 4 Cyl 2.5 L GAS
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Mazda 3 Expansion Tank Part Number: PEAR-15-351
$50.08 MSRP: $66.78
You Save: $16.70 (26%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Tank, Sub-Radiator; Expansion Tank
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2014-2018 Mazda 3 | Grand Touring, i Grand Touring, I Sport, i SV, I Touring, s Grand Touring, s Touring, Sport, Touring | 4 Cyl 2.0 L GAS, 4 Cyl 2.5 L GAS
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Mazda 3 Reservoir Assembly Part Number: PAF3-15-360A
$52.84 MSRP: $70.46
You Save: $17.62 (26%)
Ships in 1-2 Business Days
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Product Specifications
- Other Name: Tank, Sub-Radiator; Reservoir Assembly
- Replaces: PAF3-15-360
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2019-2024 Mazda 3 | 2.0, 2.5 S, Base, Carbon Edition, Preferred, Premium, Select, Select Sport | 4 Cyl 2.0 L GAS, 4 Cyl 2.5 L GAS
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Mazda 3 Reservoir Part Number: LF8B-15-350B
$59.00 MSRP: $78.68
You Save: $19.68 (26%)
Ships in 1-2 Business Days
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Product Specifications
- Other Name: Tank, Sub-Radiator; Expansion Tank, Reservoir
- Replaces: LF8B-15-360A, LF50-15-350A, LF50-15-350, LF8B-15-350A, LF50-15-350B, LF8B-15-350, LF8B-15-360, LF50-15-350C, LFR5-15-360
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2004-2013 Mazda 3 | i, Mazdaspeed, S, SP23 | 4 Cyl 2.0 L GAS, 4 Cyl 2.3 L GAS
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Mazda 3 Reservoir Part Number: PX4J-15-730
$75.90 MSRP: $101.23
You Save: $25.33 (26%)
Ships in 1-2 Business Days
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Product Specifications
- Other Name: Sub Tank; Reserve Tank, Reservoir
- 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 Expansion Tank Part Number: L3CE-15-350A
$81.11 MSRP: $108.17
You Save: $27.06 (26%)
Ships in 1-2 Business Days
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Product Specifications
- Other Name: Tank, Sub-Radiator; Expansion Tank
- Replaces: L3CE-15-350, L512-15-350, L512-15-350A
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2010-2013 Mazda 3 | i, Mazdaspeed, S | 4 Cyl 2.0 L GAS, 4 Cyl 2.3 L GAS, 4 Cyl 2.5 L GAS
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Mazda 3 Reservoir Part Number: L33X-15-350E
$104.81 MSRP: $139.78
You Save: $34.97 (26%)
Ships in 1-2 Business Days
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Product Specifications
- Other Name: Tank, Sub-Radiator; Reservoir Tank
- Replaces: L33X-15-350C, L33X-15-350B, L33X-15-350D
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2007-2009 Mazda 3 | Mazdaspeed, S | 4 Cyl 2.3 L GAS
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Mazda 3 Expansion Tank Part Number: PX4J-15-360B
$126.99 MSRP: $169.35
You Save: $42.36 (26%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Tank, Sub; Expansion Tank, Reservoir Tank
- Replaces: PX4J-15-360A
- 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

Mazda 3 Coolant Reservoir

The Mazda 3 Coolant Reservoir serves as a safety buffer that holds expanding coolant, prevents the entry of air into the closed cooling loop, and prevents harmful antifreeze from dripping on the road. This plastic tank is attached to the radiator and is part of the Mazda 3 cooling system, with hot and cold level lines that allow drivers to quickly estimate the amount of fluid when the engine is cold. Heat causes increased pressure that forces coolant through a small hose into the Coolant Reservoir, and upon cooling of the engine, the vacuum pulls the liquid back and keeps the radiator topped up and free of corrosion-causing air. Mazda cars have applied two primary styles throughout the years. The first overflow-tank system puts the pressure cap on the radiator at the front of the assembly, and the reservoir cap is just a simple piece of plastic, so only coolant passes in and out. Subsequent expansion-tank designs relocate the pressure lid to a more robust reinforced Coolant Reservoir that is placed at the high point of the circuit, allowing compressed air, instead of fluid, to escape during pressure increases. The pressurized design of the cap in both cases can open under excess pressure and also close in cold conditions, saving weight as the cap requires less coolant in the radiator. All Mazda 3 drivers are expected to maintain the fluid line within the expected limits to ensure that the operating temperatures remain stable regardless of the generation.

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Mazda 3 Coolant Reservoir Parts and Q&A

Reservoir
L33X-15-350E
Q: How to drain and clean the coolant reservoir on Mazda 3?
A:
Empty the cooling system until the reservoir is emptied. When provided with the original hose clamps, have them remove the clamps of the smaller hoses with the pliers and also disconnect the hoses to the reservoir. Take off the screw attaching the reservoir to the inner fender panel. Pick up the tank and detach it at the front mounting tab and unhook the hose on the bottom of the tank. Use soapy water and brush to clean out the tank and make sure that inside the tank no deposits have been left, also check the reservoir well and in case there is a crack then change the reservoir. Removal is the other side of installation after which the cooling system is filled.