Valve outer disc Manufacturer & Supplier – EMD 645 & 710 Parts

Overview

These inner and outer discs are the internal seating components of the cylinder indicator (test) valve fitted to each EMD 645/710 cylinder head — the same valve used for blowdown venting and for taking peak-pressure readings. They come in a small range of sizes to match different indicator valve bodies across the engine family.

How It Works in the Engine

The disc is what actually seats and seals inside the indicator valve body when it's closed, and lifts off its seat when the valve is opened for blowdown or a pressure reading. Because it's a small, hardened wear part sitting directly in the combustion gas path, it takes the seating wear so the valve body itself doesn't have to be replaced or re-machined.

Signs You Need a Replacement

• Valve won't seal fully closed, showing as a slow leak past the seat
• Pitting or erosion on the disc face from repeated blowdown cycles
• Inconsistent or unreliable pressure readings taken through that valve
• Disc size mismatch with the valve body, usually from mixing part numbers during a repair

Why Source This From Apex International

Each size — small, medium, and large — is checked against its EMD/DLW reference number before shipping, so the disc seats correctly in the valve body it's meant for instead of relying on a close-enough universal fit.