Water Pump 6684225 6653941 | Direct Fit for Bobcat Kubota D1402

Cross-Reference Verified — We map 6684225 and 6653941 to specific Kubota D1402 engine serial ranges so the Water Pump for Bobcat S150-S185 / Kubota D1402 cross reference fitment bolts on without port modification.

Technical Specifications

Application Suitability

Why Superseded Numbers Keep Sending the Wrong Water Pump for Bobcat S150-S185 / Kubota D1402 Cross Reference Fitment to the Jobsite

Cross-reference tables copied between sellers carry forward errors from the original source, so a superseded number like 6684225 gets applied to engine builds that actually need 6653941, or vice versa.

In the Pearl River Delta supply chain, I have watched a Bobcat S150 sit idle for a full week because the buyer trusted a cross-reference that did not account for a production mid-run change in the Kubota D1402 thermostat housing interface. The old part number still showed as valid in three different online catalogs. All three were wrong for that specific engine serial range [NEED_CITE: engine serial breakpoint documentation for Kubota D1402 water pump interface changes]. The pump physically mounted, but the coolant inlet port sat 8 millimeters off the hose routing path. A small mismatch on paper becomes a machine-down event on the ground.

Coverage Across the Bobcat Skid Steer and Toolcat Range

This replacement water pump addresses the full span of Bobcat loaders that left the factory with the Kubota D1402 — from the early 643 and 645 through the current-production S150, S160, S175, and S185. The fitment list extends to the Toolcat 5600 utility vehicle, the B300 and BL370 backhoe loaders, and the 1600 wheel loader. Each machine model on that list represents at least one documented instance where a generic cross-reference failed to account for a variant difference within the base engine block. We verify the serial range against our own fitment records before confirming any order.

Interface Details That Separate a Direct Fit from a Field Modification

The Kubota D1402 was produced across multiple equipment platforms, and Bobcat adapted the engine mounting and accessory drive arrangement differently for a skid steer versus a backhoe loader versus a wheel loader. The water pump mounting bolt pattern remains consistent across most variants, but the coolant outlet port orientation and the hose connection diameter shift between production runs. When we verify a fitment, we check the port clocking position against the machine serial number, not just the base engine model [NEED_CITE: coolant port orientation variance across Kubota D1402 equipment platform adaptations]. A pump that bolts on but forces the upper radiator hose into a kink will cause overheating within the first hour of operation — the exact failure mode the original pump was replaced to prevent.

Reading the Specifications That Actually Matter on a Replacement Pump

Impeller blade count and housing casting geometry determine the flow rate at the D1402 operating RPM range. An impeller with fewer blades or a shallower vane profile moves less coolant per revolution, which does not show up at idle but causes temperature creep under sustained load — the condition where a skid steer running a trenching attachment needs cooling capacity the most. The housing material must tolerate the glycol-water mixture at operating temperature without galvanic corrosion where dissimilar metals meet at the thermostat housing junction. Bearing preload inside the pump shaft sets the seal lifespan; excessive preload wears the mechanical seal face prematurely, and insufficient preload allows coolant weepage past the seal lip within the first few hundred hours.

What Happens When Fitment Verification Gets Skipped

A water pump that arrives with the wrong port orientation forces the technician to either reroute hoses — introducing bend radii that restrict flow — or return the part and wait for a replacement. Both paths keep the machine down. A pump that bolts on but carries an incorrect impeller specification runs cool at the yard check and overheats on the first full-shift job [NEED_CITE: coolant flow rate requirements for diesel engines under sustained hydraulic load]. The second failure gets blamed on the radiator or the thermostat, sending the diagnosis in the wrong direction and extending downtime further. The cost of the wrong pump is never the pump itself; it is the second round of teardown, the second round of coolant disposal, and the second round of waiting.

Why Buyers Consolidate This Fitment Check With Us

We verify 6684225 and 6653941 against the actual machine serial number, not just the model designation, so variant differences get caught before dispatch rather than on the shop floor. Our cross-reference database is built from teardown records and serial-range breakpoints, not copied from third-party listings that may carry forward outdated supersession chains. We offer a sample unit for physical fitment trial before a fleet operator commits to stocking quantities across a mixed-model Bobcat fleet. Identification from a worn nameplate or a painted-over data plate is routine here — a clear photograph of the machine model tag is enough for our technical team to narrow the serial range and confirm which pump number applies. All production runs, whether from our own facility or from qualified ISO-certified manufacturing partners, carry identical warranty terms and quality inspection standards.

Documentation & Verification

• Commercial invoice listing both cross-reference numbers marked as reference only for customs clearance
• Fitment confirmation sheet mapping your machine serial number to the verified pump variant
• Dimensional inspection record covering bolt pattern, port diameter, and outlet orientation
• Warranty terms document specifying coverage period and manufacturing defect scope
• Packing photographs showing part labeling and protective packaging before crate closure
• HS code provided with export declaration support for destination-country customs requirements

Fitment Check Before Installation

• Compare the bolt hole spacing on the new pump flange against the removed unit before cleaning the engine block face
• Verify the coolant outlet port clocking position matches the upper hose routing path on your specific Bobcat serial range
• Rotate the impeller shaft by hand to confirm smooth bearing travel with no lateral play before mounting
• Trial-fit the hose connections dry to confirm diameter match and clamp clearance before adding coolant
• If any interface dimension disagrees with the old unit, halt installation and contact our technical team with photographs

Get the Right Pump Confirmed Before You Order

Send us your Bobcat machine model and serial number, or a photograph of the nameplate if it is still legible. If the nameplate is gone, a clear shot of the engine block casting number and the machine data tag gives us enough to confirm which of the two cross-reference numbers fits your build. For fleet buyers running multiple Bobcat serial ranges, we cross-check the entire list and flag any machines where the pump variant differs within the same model family.

Frequently Asked Questions

Q: How do I confirm this water pump fits my specific Bobcat loader serial number? A: Provide your machine model and serial number, or a photograph of the nameplate. We cross-check your serial against our fitment database to confirm whether 6684225 or 6653941 is the correct reference for your specific engine build. This verification covers serial-range breakpoints that generic cross-reference tables often miss.

Q: Are 6684225 and 6653941 interchangeable, or does my engine build require one specific number? A: They are not universally interchangeable. The two numbers map to different production runs of the Kubota D1402, with variant differences in port orientation or mounting detail. We verify which number applies to your engine serial range before confirming fitment, so the pump you receive matches your specific build.

Q: My nameplate is worn off — can you identify the correct pump from just the machine model? A: Often yes. A clear photograph of the engine block casting number, combined with the machine model, allows us to narrow the serial range and confirm the applicable water pump reference. For older Bobcat units where multiple variants exist within one model, we may ask for an additional photo of the thermostat housing area.

Q: Why does the same base part number appear with different variants across model series? A: Bobcat adapted the Kubota D1402 for different equipment platforms — skid steer, backhoe, wheel loader — and each adaptation can shift accessory mounting or coolant routing. A pump that fits a 753 skid steer may not match the port layout on a B300 backhoe, even though both use the same base engine. We verify per machine, not per engine model alone.

Q: Can I order a sample to verify fitment before placing a larger order? A: Yes. We supply sample units for physical fitment confirmation before you commit to fleet-level quantities. This is particularly useful for mixed-model Bobcat fleets where serial ranges span multiple production runs and a single part number may not cover every machine in your inventory.