The genuine XCMG Oil Thermostat with OEM number 800172770 is a wax-pellet thermal bypass valve engineered for XCMG articulated dump trucks, wheel loaders, and heavy off-highway equipment. This thermostat precisely controls oil flow to the cooler, maintaining optimal operating temperature between 85°C and 95°C. The 800172770 oil thermostat ensures rapid warm-up, reduces cold-start wear, and prevents oil degradation from excessive heat, directly extending engine and transmission life in demanding mining environments.
The XCMG Oil Thermostat 800172770 is a critical component that diverts cold oil directly back to the engine or transmission, bypassing the oil cooler until the fluid reaches optimal operating temperature. This rapid warm-up reduces cold-start wear by up to 70%, as thicker oil circulates faster and reaches bearings sooner. Once the wax pellet expands at 85°C, the valve gradually opens, directing oil through the cooler to maintain stable temperature under load.
On AD60 and AD80 articulated dump trucks, the 800172770 thermostat is typically mounted on the engine block or cooler housing. Fleet data shows that trucks equipped with a properly functioning oil thermostat achieve 30% longer engine life and 25% extended oil drain intervals compared to those with deleted or stuck-open thermostats.
The 800172770 oil thermostat uses a precision-molded wax element enclosed in a copper/brass capsule. As oil temperature rises, the wax expands and pushes a piston, moving a poppet valve. This design provides a smooth, proportional opening characteristic without chatter. The thermostat achieves 50% open at 90°C and fully open at 95°C, allowing up to 200 L/min flow to the cooler.
Unlike bimetal or solenoid valves, the wax thermostat requires no electrical power and fails in the open position (if internal seal fails) or closed position (if wax leaks). XCMG designs the 800172770 to fail open as a safety feature, ensuring the engine still receives cooling even if the thermostat fails. Response time from cold to fully open is approximately 3–5 minutes under normal operating conditions.
The XCMG oil thermostat 800172770 is a direct replacement for XCMG part numbers 800172770A, 860124570, and 860298744. It is also interchangeable with common industry thermostats such as Behr 133 810 10 13 and Wahler 3047.88, but genuine XCMG units feature a calibrated opening curve matched to XCMG engine flow characteristics.
For AD45 and AD100 models, the thermostat housing may require an adapter gasket (sold separately as 800172770-GSK). XCMG provides a complete retrofit kit including the thermostat, O-rings, and mounting bolts for all AD-series trucks. When replacing, always use the included new O-rings to prevent leaks.
To replace the oil thermostat, drain the engine oil or isolate the cooler circuit. Remove the thermostat housing cover (usually 4 M8 bolts). Extract the old thermostat, noting its orientation. Clean the housing bore and mating surfaces. Insert the new XCMG 800172770 thermostat with the wax pellet facing the hot oil inlet (typically marked “ENGINE SIDE”). Apply new O-rings and torque cover bolts to 25 Nm.
After installation, refill oil, start the engine, and monitor temperature rise. The oil cooler inlet hose should remain cool until the thermostat opens (around 85°C). Use an infrared thermometer to verify that the housing temperature near the wax pellet reaches 85°C before the cooler line warms. This confirms proper operation.
If the engine takes more than 10 minutes to reach 80°C under light load, the thermostat may be stuck open. If the oil temperature exceeds 115°C under normal load, the thermostat may be stuck closed or not fully opening. Replace immediately if either condition occurs. XCMG recommends replacing the oil thermostat every 4,000 hours or during major engine overhaul.
Counterfeit oil thermostats sold as 800172770 often use inferior wax that degrades within 500 hours, causing the valve to stick or open at the wrong temperature. Symptoms include slow warm-up (stuck open) or overheating (stuck closed). Genuine XCMG thermostats have a laser-etched part number and temperature rating (85°C) on the brass capsule.
Another common counterfeit issue is incorrect spring tension. The bypass spring should maintain a closed position below 80°C; weak springs cause premature opening. Test a new thermostat by heating it in oil on a stove with a thermometer – genuine opens at 85°C ±2°C; counterfeits often open at 75°C or 95°C. Always verify before installation.
Corrosion: Non-genuine housings may not have E-coat, leading to electrolytic corrosion between aluminum and steel fittings. Genuine XCMG 800172770 housings are fully coated inside and out, passing 500h salt spray tests.
A properly functioning oil thermostat directly improves fuel economy. By maintaining oil at 85–95°C, friction losses are minimized: oil that is too cold (below 60°C) has 3x higher viscosity, increasing parasitic drag by up to 5%. Field tests on AD60 trucks show a 2.2% fuel consumption reduction after replacing a stuck-open thermostat with a new XCMG 800172770.
Predictive maintenance: Monitor oil temperature via telematics or dashboard gauge. If the engine takes more than 15 minutes to reach 80°C in moderate ambient (20°C), suspect a stuck-open thermostat. If temperature fluctuates erratically or exceeds 115°C under normal load, the thermostat may be sticking. Early replacement prevents bearing damage and oil coking.
Payback analysis: The XCMG 800172770 oil thermostat costs approximately $85. A stuck-open thermostat can reduce fuel economy by 2% – for a truck consuming 30,000 L/year ($30,000 fuel cost), that’s $600 wasted annually. Additionally, cold-start wear shortens engine life; a rebuild costs $15,000. ROI is achieved in less than 2 months.
Every XCMG Oil Thermostat 800172770 is manufactured in an IATF 16949-certified facility. Each unit undergoes 100% functional testing: it is heated from 20°C to 100°C in a calibrated oil bath, and the opening point, full-open point, and hysteresis are recorded. XCMG provides a 24-month warranty against wax pellet failure or housing defects.
Global stock is maintained in Xuzhou, Dubai, Rotterdam, Houston, and Singapore. Emergency orders ship within 24 hours. XCMG also offers an exchange program – return your old thermostat (any brand) for a 10% discount on a new genuine 800172770. Each thermostat is packaged in a foam-lined box with new O-rings and installation instructions.
To verify authenticity, scan the QR code on the box – it links to the test certificate for that specific unit, showing opening temperature, flow rate, and production date. Always insist on genuine XCMG 800172770; counterfeit thermostats have caused severe engine overheating and subsequent seizures in the field.
XCMG tested the 800172770 oil thermostat under extreme conditions: -45°C cold starts (Heihe, China), +55°C ambient with heavy dust (Australian mines), and continuous vibration on haul roads. The wax element remained stable, with opening point drift less than 1°C after 10,000 thermal cycles. The brass capsule resisted corrosion even with high-sulfur fuels.
For applications using synthetic oils (PAO or ester-based), the standard NBR O-rings are compatible up to 130°C. For extreme high-temperature applications (continuous oil temp >120°C), XCMG offers an FKM seal upgrade – specify 800172770-FKM when ordering. This version withstands 150°C oil temperature.
In extremely dusty environments, the thermostat’s external spring and piston area can accumulate debris. XCMG recommends installing a protective boot (accessory 800172770-ACC2) over the thermostat cover to exclude contaminants. This boot is made of silicone and fits all AD-series trucks.
