The order we never skip — which is why the wrong part does not reach your site.
01
Confirm
Nameplate, OEM number and working conditions — checked against your machine, confirmed in writing before you pay.
02
Verify
Photos and video of the actual part, packed and labelled, before it leaves. What you see is what ships.
03
Prevent
Send the hour-meter reading and we log the service interval — you get a message before the next one is due.
04
Dispatch
Nothing leaves Xi’an until you reply "ok". You approve, then we ship — not the other way round.
Confirm this part for my machine
Machine model and part number are what let us confirm fitment in writing. Message is optional.
Overview
Fitment Note: Confirmed by the removed valve number and its head diameter. 37 mm head. The quantity depends on the engine - tell us your engine and we confirm the number; inlet valves quoted separately.
Aftermarket exhaust valve 5I-7739A — a direct replacement for the Caterpillar 5I-7739 valve. It fits the Caterpillar 3066 / S6K / C6.4 diesel engine family (also 3064 / C4.2), commonly used on CAT 311 / 311B / 311C / 312B / 320 / 320B / 320C / 320D excavators. Valve head diameter 37 mm.
The exhaust valve opens to release burnt gases and closes against the seat to seal compression. It works hotter than the inlet valve, so it is more prone to burning, tuliping and seat recession — typical signs are rough running, hard starting, a drop in power and overheating. Exhaust valves are normally inspected and replaced during a cylinder-head overhaul. Supplied as a single valve.
Tell us the engine and the quantity — the number of valves depends on the engine. Confirm the removed valve number and its head diameter before ordering.
Low compression, hard starting, a misfire or power loss on one cylinder, high exhaust temperature, overheating; a burnt valve or recessed seat leaks badly.
Installation Tips
1. Check the valve guide and seat for wear; recut / replace the seat if pitted or recessed.
2. Lapping the valve to the seat is recommended before final fitting.
3. Check the valve stem for straightness and fit new stem seals.
4. Re-set valve clearance to the engine specification after assembly.
