MD787131 Mitsubishi Engine Water Pump For 6D16 6D15 Engine

MD787131 Water Pump for Mitsubishi 6D16 6D15 Engine

1. Quick Notice
MD787131 water pump for Mitsubishi 6D16 and 6D15 diesel engines. Direct fit replacement unit. Complete assembly with cast iron housing and pressed impeller. No gasket included. Verify engine model and mounting pattern before ordering. Professional installation recommended.

2. Description
The MD787131 water pump is a bolt-on coolant circulation component designed for the Mitsubishi 6D16 and 6D15 naturally aspirated and turbocharged diesel engines. These inline six-cylinder engines are commonly found in medium-duty trucks, bus chassis, and industrial equipment applications requiring continuous duty cycles with stable thermal management.
This water pump is manufactured as a complete assembly. The housing is constructed from high-density cast iron, which resists cavitation erosion and provides a stable mounting surface for the pulley and belt tension. Unlike stamped steel housings, the cast iron construction of the MD787131 maintains bolt torque retention across repeated thermal cycles from cold start to full operating temperature.
The impeller inside the housing is pressed onto a sealed bearing shaft. It uses a closed-vane design with curved blades optimized for the flow volume requirements of the 6D16 and 6D15 cooling systems. The impeller diameter and blade angle match original factory specifications to deliver correct coolant velocity through the engine block, cylinder head, and radiator core without generating excessive back pressure or cavitation bubbles at high RPM.
A integrated mechanical seal sits directly behind the impeller. This seal uses a carbon face against a ceramic stationary seat, creating a leak-proof barrier between the coolant and the bearing cavity. The seal is pre-lubricated at the factory and requires no running-in period when installed correctly.
The bearing assembly is a double-row sealed ball bearing type, packed with high-temperature grease. The bearing is not serviceable. The shaft extends through the housing front cover and accepts the standard drive pulley and fan hub used on 6D15 and 6D16 accessory drives. Shaft diameter and keyway dimensions match original equipment.
Three mounting bolt holes on the pump flange align with the timing gear housing on the engine front plate. A separate paper or rubber gasket is required for sealing between the pump flange and the engine block surface. No gasket is supplied with this pump. The bypass hose connection port is located on the upper section of the housing.
This replacement pump is suitable for engines experiencing coolant leaks from the shaft seal, bearing noise, impeller erosion, or housing cracks. Always flush the entire cooling system before installing a new water pump to remove debris that could damage the new seal or restrict radiator tubes.

3. Parameter Table

4. Custom Content
Installation notes for MD787131 water pump. Replace the mounting gasket each time the pump is removed. Apply no additional sealant unless specified by the engine manual. Torque mounting bolts to 24 to 30 Nm in a crossing pattern. Fill cooling system with correct antifreeze mixture after installation. Run engine with radiator cap open to purge air trapped behind the thermostat. Top up coolant level after first warm-up cycle. Inspect drive belt tension after 50 operating hours. Do not use sealants or stop-leak additives with this pump. The bypass hose connection accepts 32 mm inner diameter hose. Retain original pulley bolts. No balancing required. Pump is ready for service directly from package. Store in clean dry environment until installation. Do not rotate the pump shaft before fitting the belt. Check that the new pump has no casting cracks around mounting ears. Compare old and new pump flange thickness before bolting down. A mismatch in flange thickness indicates wrong application.

5. FAQ (Q&A Format)
Q1: Which engines accept the MD787131 water pump?
A1: This pump fits Mitsubishi 6D16 and 6D15 diesel engines. It does not fit 6D14, 6D17, or 6D22 without checking housing dimensions first.
Q2: Is this a complete pump assembly?
A2: Yes. The pump includes housing, bearing, shaft, seal, and impeller as one assembled unit. No internal components require separate ordering.
Q3: Does the pump come with a mounting gasket?
A3: No. A separate gasket is required between the pump flange and engine block. Order the correct gasket for your engine.
Q4: What is the rotation direction of this pump?
A4: Rotation is clockwise when viewed from the pulley side facing the pump. Reversing belt routing will damage the impeller.
Q5: Can this pump be installed on both 6D15 and 6D16 without modification?
A5: Direct fit on both engines provided the original pump part number is MD787131. Check pulley bolt pattern match before installation.
Q6: What causes seal failure in these water pumps?
A6: Common causes include contaminated coolant, improper antifreeze concentration, loose drive belt tension, and cavitation from low coolant level.
Q7: Does the bearing require periodic lubrication?
A7: No. The bearing is permanently sealed and lubricated. No grease fitting exists on this pump.
Q8: What torque value is used for mounting bolts?
A8: Torque three mounting bolts to 24 to 30 Nm. Use a crossing pattern. Overtorque may crack the cast iron flange.
Q9: Is coolant required for bench testing before installation?
A9: No. Dry spinning the pump by hand confirms smooth rotation but does not test seal function. Install on engine and fill with coolant for actual testing.
Q10: How can I identify a failed pump before removal?
A10: Symptoms include coolant leaking from the weep hole near the pulley, grinding bearing noise, excessive pulley wobble, and engine overheating at highway speed.