This ATE brake master cylinder reservoir cap (PN 390425) seals the brake fluid reservoir to keep moisture and debris out on the Porsche applications listed below. ATE, a division of Continental AG, has been engineering hydraulic brake systems in Germany for over a century. An OEM supplier to manufacturers like Porsche AG, Mercedes-Benz, and Volvo, ATE produces factory-level rotors, pads, and hydraulic components built to strict European standards. Known for consistent pedal feel, proper fitment, and long service life, ATE remains a trusted choice for reliable, OE-quality braking performance.

Technical Details

Manufacturer part number: 390425
OE reference: 477 611 361 (477611361)
Function: Seals the brake fluid reservoir to reduce contamination and help prevent leaks at the cap
Quantity required: 1 per car
Best practice: Replace the cap if the seal is hardened or if the reservoir has been opened for long-term storage

Fitment & Compatibility

Use the fitment table below to confirm year and model (356/914/924/928). Always verify reservoir style and level-sensor configuration where applicable.

If you’re sorting out reservoir parts, grommets, or master cylinder plumbing, send us your VIN and a quick description of what’s on the car now. We’ve been doing Porsche brake work for over 20 years, and we can help you avoid ordering the wrong reservoir hardware.

Year	Make	Model
1956	Porsche	356A
1957	Porsche	356A
1958	Porsche	356A
1959	Porsche	356A
1960	Porsche	356B
1961	Porsche	356B
1962	Porsche	356B
1963	Porsche	356B
1964	Porsche	356C
1965	Porsche	356C
1964	Porsche	356SC
1965	Porsche	356SC
1970	Porsche	914
1971	Porsche	914
1972	Porsche	914
1973	Porsche	914
1974	Porsche	914
1975	Porsche	914
1976	Porsche	914
1977	Porsche	924
1978	Porsche	924
1979	Porsche	924
1980	Porsche	924
1981	Porsche	924
1982	Porsche	924
1978	Porsche	928
1979	Porsche	928
1980	Porsche	928
1981	Porsche	928
1982	Porsche	928
1983	Porsche	928
1984	Porsche	928
1985	Porsche	928
1986	Porsche	928
1987	Porsche	928

Brake Fluid

ATE Brake Fluid Reservoir Cap for Porsche 356/914/924/928 (1956–1987)