Used Genuine BMW E12 / E21 Coolant Expansion Tank – 17111120363

Used original BMW coolant expansion tank for selected BMW E12 and E21 models with an M20 engine.

The tank is fitted in the engine cooling system and allows coolant expansion as the engine reaches operating temperature. It features the original BMW moulding, integrated mounting points, hose connections and the casting number 1120363.

The original coolant cap is included as shown in the photographs.

Product details

• Product: Coolant expansion tank
• Alternative description: Coolant reservoir
• German description: Ausgleichsbehälter
• Manufacturer: Genuine BMW
• BMW part number: 17111120363
• Formatted BMW number: 17 11 1 120 363
• Casting/reference number: 1120363
• Installation position: Engine bay
• System: Engine cooling system
• Engine application: Selected M20 engines
• Material: Moulded translucent plastic
• Cap: Included
• Condition: Used
• Quantity supplied: One expansion tank

Vehicle compatibility

Suitable for selected BMW models using the corresponding expansion-tank design, including:

BMW E12

• BMW 520 with M20 engine
• Selected late E12 520 configurations

BMW E21

• BMW 320 with M20 engine
• BMW 323i with M20 engine
• Selected E21 sedan models with the corresponding cooling-system layout

Fitment depends on the engine, production date, market specification, radiator layout and hose connections. This tank is not guaranteed to fit every E12 or E21 model.

Always compare the tank shape, mounting points, hose connections, cap opening and casting number with the original component before ordering.

BMW and reference numbers

• 17111120363 – BMW coolant expansion tank
• 17 11 1 120 363 – Formatted BMW catalogue number
• 1120363 – Casting/reference number visible on the tank

The coolant cap shown in the photographs is included.

Condition

Used original BMW component with visible age- and use-related wear, including:

• Heavy yellowing and discolouration of the plastic
• Surface dirt and storage marks
• Scratches and cosmetic marks
• Aged plastic around the mounting points
• Possible coolant residue and staining
• Age-related brittleness may be present

The tank has not been pressure-tested or leak-tested. Carefully inspect the tank around the seams, mounting points, hose connections and cap opening before installation.

No guarantee can be given that the aged plastic will remain leak-free under operating pressure.

Supplied exactly as shown in the photographs.

Included

• One used genuine BMW coolant expansion tank
• One coolant cap as shown in the photographs

The following are not included:

• Coolant hoses
• Radiator
• Thermostat housing
• Additional brackets or mounting hardware not visible in the photographs
• Coolant or installation materials

Installation recommendation

Before installation:

• Compare the tank with the original component
• Inspect the plastic for cracks and stress marks
• Check all hose connections carefully
• Inspect the mounting points
• Check the cap and sealing surface
• Pressure-test the cooling system after installation
• Use new hose clamps where required
• Fill the system with the correct coolant mixture
• Bleed the cooling system correctly
• Check for leaks after the engine reaches operating temperature

Because a failed expansion tank can cause sudden coolant loss and engine overheating, professional inspection is recommended.

Storage location: 204