CAT 078-5358 SIEGE DE FAU

CAT 078-5358
Official Name: SIEGE DE FAU (French) → Valve Seat / Valve Cone Seat
Type: Precision sealing valve seat for hydraulic/fuel control valve bodies, check valves, overflow valves, and other applications.
Core Specifications (CAT Original Standard)
Part Number: 078-5358
Material: High-hardness alloy steel / carburized and quenched steel (CAT MES standard)
Surface: Precision ground, conical seal, surface hardness HRC 58–62
Sealing Cone Angle: 60° / 90° (depending on valve body, original standard conical surface)
Function: Forms a high-pressure seal with the valve core (valve cone) to prevent internal leakage and ensure stable pressure.
Compatible Systems and Typical Applications
Compatible with: 3044C / 3054C engine fuel system, hydraulic pilot control module
Models: 306E / 307E excavators, 226B3 / 246B3 Skid Steer Loader
Location: Check Valve / One-Way Valve / Relief Valve Internal Seat, mating seal with valve core
Installation and Maintenance Points

Before installation, the valve bore, valve seat, and valve core must be cleaned to remove iron filings and impurities.

For press-fit/threaded installation, the valves must be coaxial; the conical surface must be free from impacts and scratches.

Use with valve cores (such as 078-0653 check seat, 078-0776 spool valve core).

If internal leakage, slow pressure build-up, or differential pressure occurs, first check the sealing surface of this valve seat.