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Fitment notes and restrictions
Description
Replace a brittle plastic tank with pressure-tested aluminum
Moroso 63791 is a direct-fit aluminum coolant expansion tank for the supported BMW E36 and Z3 applications. It uses the factory mounting points and clip-on hose connection while replacing the failure-prone plastic body and threaded neck.
Key Features
- Moroso 63791 is fabricated from aluminum
- Direct bolt-in design using factory mounting points
- Accepts the factory clip-on hose without cutting
- Billet aluminum filler neck
- Pressure tested for leak-free operation
- Includes a 24 psi radiator cap
- Made in the USA
Fitment
| Years | Make | Chassis / Model | Verified Notes |
|---|---|---|---|
| 1992-1999 | BMW | E36 3 Series | Verified six-cylinder applications include 323i, 325i, 328i, and M3 body variants listed by the retailer catalog. |
| 1996-2002 | BMW | Z3 | Confirm the factory two-piece expansion-tank layout and clip-on hose before installation. |
Specifications
| Detail | Value |
|---|---|
| Manufacturer Part Number | 63791 |
| Product Type | Coolant expansion tank |
| Material | Fabricated aluminum |
| Installation | Direct bolt-in |
| Hose Connection | Factory clip-on style |
| Cap | Moroso 63324, 24 psi |
| UPC | 084663637919 |
| Country of Origin | USA |
What's Included
- One Moroso 63791 aluminum expansion tank
- One Moroso 63324 radiator cap
- Integral mounting brackets and fittings shown with the exact tank
About Moroso
Moroso manufactures racing and performance fluid-control components in the United States. Its direct-fit expansion tanks replace application-specific factory plastic assemblies with welded aluminum while retaining the documented hose and mounting layout.
Related Parts
- No internal hose, thermostat, water pump, radiator, or coolant is linked because each companion part must be verified for the exact BMW chassis, engine, and cooling-system layout.
FAQ
What is the 63791?It is a direct-fit aluminum coolant expansion tank for the supported BMW E36 and Z3 cooling systems.
Is a radiator cap included?Yes. The verified kit includes a 24 psi Moroso cap.
Does installation require cutting the factory hose?No. The tank accepts the matching factory clip-on hose connection.
Is the tank plastic or aluminum?It is fabricated from aluminum with a billet aluminum filler neck.
Does it fit every E36?No. Confirm the supported six-cylinder application and the original tank, hose, and mounting layout before ordering.
Does it fit the Z3?The manufacturer lists 1996-2002 Z3 applications, subject to matching the factory cooling-system configuration.
Is coolant included?No. Use only coolant mixed and specified for the exact BMW cooling system.
What should be checked after installation?Pressure-test the system, bleed it with the BMW procedure, verify fan operation and coolant level, and inspect every connection for leaks.
Installation Instructions
- Confirm the BMW chassis, model year, engine, factory expansion-tank layout, and Moroso 63791 before draining coolant.
- Allow the engine to cool completely, relieve pressure safely, and capture coolant for proper disposal or reuse only if serviceable.
- Disconnect the level sensor and factory clip-on hose, then remove the original tank without damaging adjacent plastic fittings.
- Install the aluminum tank at the factory mounting points and reconnect the verified hose and sensor without forcing either connection.
- Fit the supplied cap, refill with the BMW-specified coolant mixture, and bleed the cooling system using the current service procedure.
- Pressure-test the system, verify operating temperature and fan function, and recheck coolant level and every connection after the first complete heat cycle.
California Proposition 65 Warning: This product can expose you to chemicals including antimony oxide and other chemicals known to the State of California to cause cancer or reproductive harm. For more information, visit www.P65Warnings.ca.gov.
