Cat 3066, C6.4 Water Pump 1786633 – 311C-323D Excavators (312C, 312D, 320C, 320D)

Fits Models At A Glance:

• Caterpillar Excavators – C Series: 311C, 312C, 312C L, 314C, 318C, 319C, 320C, 320C FM, 320C L, 321C
• Caterpillar Excavators – D Series: 311D LRR, 312D, 312D L, 313D, 314D CR, 314D LCR, 315D L, 318D L, 319D, 319D L, 319D LN, 320D, 320D FM, 320D FM RR, 320D GC, 320D L, 320D LN, 320D LRR, 320D RR, 321D LCR, 323D L, 323D LN, 323D SA

Key Notes:

• Part Number(s): 1786633 (178-6633)
• Application: Engine water pump group for Cat 3064, 3066, C4.2 and C6.4 engines
• Interchange Numbers: 2128555 (earlier 320C–323D pump); Cat Reman 10R7555
• Serial Number Notes: Engine-matched — fits the Mitsubishi-based 3064/3066 and C4.2/C6.4 engines used in the 311C–323D excavators. Match the engine on your plate, not just the model.
• Shipping Restrictions: Ships UPS Ground
• Condition: Aftermarket replacement part

Common Use Case or Symptoms:

Use when coolant drips from the weep hole, the pump bearing growls, or a 320C or 320D creeps toward the red at idle with a full radiator.

Why Choose Broken Tractor:

• ✅ The 320-class water pump, one number — Cat's 3066/C6.4 pump covers 33 excavators from the 311C to the 323D.
• ✅ Cross-references included — Earlier number 2128555 and the Reman number so an old book still lands here.
• ✅ Fast Shipping from a U.S.-Based Team — ready to ship from our U.S. warehouses.