8976020353 Excavator ISUZU 6HK1 Engine Thermostat

Part number 8976020353 (also commonly written as 8-976002035-3/8976020353-ORG) is the original coolant thermostat (Thermostat A, commonly known as the "water tank") for the Isuzu 6HK1 series diesel engine, with an opening temperature calibration of ≈ 76.5 ° C. It is installed in the cylinder head outlet/thermostat housing and works in combination with another T-82 ° C (part number commonly 8981587780/8981587781) at the same location (two cannot be mixed or replaced in reverse). As a genuine Hitachi/Isuzu component, it is mainly compatible with Hitachi ZAXIS platform excavators equipped with 6HK1, typical models such as ZX330-3, ZX350-3, ZX360H-3G, etc.

This is a wax thermostat: the internal precision paraffin wax is heated and expanded, gradually opening the main valve to switch between "small circulation/large circulation" of the coolant, stabilizing the engine operating temperature in the high-efficiency range. The opening point of the main valve of the original 8976020353 is approximately 76.5 ° C. The valve body/seat and spring are calibrated according to the flow rate of the 6HK1 cooling system and the size of the water channel. The outer circle is matched with the housing seat hole, and the upper and lower sealing surfaces (usually equipped with rubber sealing rings/metal positioning edges) can be reassembled without jamming or uneven wear. It does not directly generate electricity or spray oil, but it determines the speed of water temperature rise, thermal equilibrium point, and warm-up smoke level: once the opening point drifts or the valve seat is not tight, it will cause "slow heating (temperature loss)" or "insufficient closure of the small cycle (precursor to boiling)".

When the water temperature is abnormal, do not come up and replace the parts: first confirm that the water tank/intercooler is not blocked, the fan/belt is normal, the coolant volume is sufficient, and there is no large amount of air (air can cause "false shutdown/temperature jump"). Disassembly and assembly must wait for complete cooling and pressure relief; The old sealing ring/old rubber should be thoroughly cleaned, and the new thermostat should be installed in the marked direction. The 6HK1 data clearly indicates that the end with an exhaust hole should be installed facing outward/towards the water outlet side (with the exhaust port facing towards the rear), and the two thermostats cannot be installed upside down. Tighten the shell bolts in a cross sequence with the specified torque (over tightening will cause deformation and leakage, over loosening will cause leakage). After installation, it is necessary to replenish the fluid and exhaust the air, and heat the water temperature. Confirm that the pointer is stable in the normal working area and the joint is not leaking.