Thermostat 6680512 for Kubota D902 D1105 – Verified Fitment

Cross-Reference Verified — Thermostat 6680512 mapped against four superseded Kubota numbers to confirm fitment before you order.

Technical Specifications

Application Suitability

When a Correct Part Number Still Fits Wrong

The thermostat 6680512 may carry the right number but still deliver incorrect opening temperature if the engine variant is not confirmed.

I have worked through cases where a buyer pulled a thermostat for a Kubota V1505 based on the part number alone, only to find the machine still ran hot after installation. The V1505 has been built across several serial ranges, and thermostat opening specifications shifted between production runs. A worn nameplate makes this worse — paint and corrosion erase the serial data you need to distinguish variants. Relying solely on a cross-reference table copied between sellers compounds the problem, because superseded numbers like 6674172 and 6653948 appear on multiple engine families with different thermal requirements [NEED_CITE: Kubota engine serial variant thermostat specifications across production runs].

Engine Serial Range Determines Fitment, Not Just the Model

A thermostat for a Kubota D1105 is not automatically interchangeable with one for a D1105T. The turbocharged variant operates under different thermal loads, and the wax element calibration may differ. The same logic applies to the V2003T Tier I versus naturally aspirated V-series engines installed across Bobcat skid steers and compact excavators. Identifying the correct thermostat 6680512 requires matching the engine serial range against the compatibility list, not just the model badge on the machine frame.

Port Orientation and Flange Pattern Must Match

Beyond the part number, physical fitment depends on the thermostat housing flange and coolant port orientation. Bobcat 743, 753, and S185 skid steers share Kubota powerplants but route coolant differently depending on chassis generation. A thermostat that fits the bore but places the sensing element on the wrong side of the flow path will open late, causing overheating under load. I always recommend comparing the removed unit against the replacement on a bench — checking flange bolt spacing, overall diameter, and the position of the wax element relative to the coolant inlet [NEED_CITE: thermostat housing flange variation across Bobcat skid steer generations].

Wax Element Calibration and Stainless Steel Housing

The wax element inside this thermostat expands at a calibrated temperature to open the coolant passage. If the element responds at a point too high or too low for the specific engine build, the cooling system cannot regulate properly — either the engine warms up too slowly in cold conditions or overheats under sustained load. The stainless steel housing resists corrosion from extended coolant exposure, which matters in machines that sit idle between seasonal work periods. Stainless construction also maintains dimensional stability across thermal cycles, so the thermostat seats consistently after repeated open-close operations.

What Happens When Fitment Is Skipped

A thermostat that barely seats or opens at the wrong temperature does not always fail immediately. The more common outcome is gradual overheating under load, misdiagnosed as a radiator or water pump issue. The machine returns to the shop weeks later with the same symptom, and the real cause — a thermostat variant mismatch — is only discovered on the second teardown. This costs labor hours, damages confidence in the parts supply chain, and leaves the equipment owner questioning every component in the cooling circuit. Requesting a sample before bulk commitment eliminates this cycle entirely [NEED_CITE: cooling system misdiagnosis caused by thermostat variant errors].

Why Source This Thermostat Through Us

We produce selected part lines in our own facility and source the remainder from qualified ISO-certified manufacturing partners — both carry the same quality control and warranty terms. Our technical team verifies cross-reference numbers 6674172, 6653948, and 3918235 against current and superseded Kubota catalogs, not just copied reference tables. We identify the correct part from a machine model, serial number, photograph, or nameplate image when the original label is illegible. Samples ship for physical fitment testing before you commit to a bulk order, so distributors and repair centres confirm the thermostat 6680512 drops into the housing correctly on the first attempt.

Documentation & Verification

• Commercial invoice listing thermostat 6680512 with cross-reference numbers marked as reference only
• Part compatibility sheet confirming engine serial range and Kubota/Bobcat machine fitment
• Dimensional inspection record covering flange bolt pattern and housing diameter
• Warranty terms document covering 3–12 months against manufacturing defects
• Packing photographs showing thermostat condition and labeling before crate closure
• HS code and customs documentation support for international shipment

Fitment Check Before Installation

• Compare flange bolt spacing on the new thermostat 6680512 against the removed unit before draining coolant
• Verify wax element orientation matches the coolant flow direction marked on the original housing
• Confirm engine serial number falls within the listed Kubota or Bobcat compatibility range
• Bench-test opening temperature in heated water if engine variant is uncertain
• Inspect thermostat housing gasket surface for warping that could cause bypass leakage
• Return sample for exchange rather than forcing fitment if bolt pattern does not align

Request Fitment Verification

Provide the engine model, serial number, or a photograph of the removed thermostat alongside the machine nameplate. If the nameplate is corroded or painted over, send images of the engine block casting numbers and the thermostat housing. Our technical team will cross-reference the part number, confirm variant compatibility, and advise whether a sample is needed before you place a full order.

Frequently Asked Questions

Q: How do I confirm this thermostat fits my Kubota engine or Bobcat machine? A: Send us the engine serial number or a photo of the removed thermostat and the machine nameplate. We cross-reference the part number 6680512 against Kubota and Bobcat serial ranges, including superseded numbers, to confirm fitment before shipping. If the nameplate is unreadable, engine block casting numbers and housing photos are enough for identification.

Q: Are 6674172, 6653948, and 3918235 interchangeable with 6680512? A: These numbers appear as cross-references across different Kubota engine generations and Bobcat machine lines. They may be interchangeable for certain serial ranges but not all. We verify each cross-reference against the specific engine variant you are working on, because superseded numbers sometimes apply to engines with different thermostat opening temperatures.

Q: My machine model has a Tier I designation — does that affect thermostat fitment? A: Yes. Tier I variants of engines like the V1703 and V2003T can have different thermal management requirements than non-Tier versions. The thermostat must match the opening temperature specified for that exact variant. Always confirm the Tier designation when requesting a compatibility check so the correct calibration is supplied.

Q: I only have the machine model, not the part number — can you identify the correct thermostat? A: Yes. Provide the machine model such as Bobcat S185 or E26, along with any visible engine markings or photographs of the existing thermostat. We trace the correct part through Bobcat machine-to-engine mapping and Kubota serial range data, then confirm the result with a cross-reference check against all known superseded numbers.

Q: Can I get a sample to test fitment before ordering in bulk? A: We supply samples for physical fitment confirmation. This is especially useful when dealing with older Bobcat machines where engine variants are difficult to determine from records alone. Install the sample, verify the thermostat seats correctly and regulates temperature as expected, then proceed with a bulk order with confidence.