Orange product names are Amazon affiliate links (we may earn a commission at no cost to you). Orange part numbers link to Amazon listings. Only the 1C011-73013 listing is genuine Kubota (OEM); the others are aftermarket parts listed under the Kubota number. Check the listing shows the exact part number, or order from a Kubota dealer.

These are general diagnostic signs, not figures published by Kubota.

A thermostat is only one cause of overheating. Check the radiator screen, coolant level and fan first, as laid out in our tractor overheating guide. A dirty or leaking radiator is covered in the radiator repair guide.

Source: Messick’s and Coleman Equipment parts catalogs and part records, checked Oct 21, 2026. Always confirm against your serial number with your Kubota dealer before ordering.

These are dealer “product replaces” lists. They show that the current part replaces each older number. A supersession is a Kubota update, so it is different from an aftermarket cross-reference.

An earlier version of this page called 15531-73014 the part “for most applications.” We could not support that, so it has been removed.

Do not treat these as figures for other tractors. We did not carry the BX numbers over to engines whose manual row we could not read. The values above are the start of opening and full opening, which are two separate figures. A number printed on an aftermarket box, such as 160 or 180 °F, is the seller’s description and not a Kubota specification.

The Kubota manual has a test titled “Checking Thermostat Valve Opening Temperature.” We could not retrieve its steps, so look it up in your model’s workshop manual. Our parts diagrams and manuals page is the place to find it.

This sequence comes from Kubota’s BX1880-AU/BX2380-AU/BX2680-AU operator’s manual, printed page 93. Other models may differ, so check yours.

• Stop the engine and let it cool.
• Open the radiator drain plug or the engine drain plug, and remove the radiator cap. The manual says the cap must come off to drain the coolant completely.
• Close the drain plug, then fill with clean soft water and a cooling-system cleaner and follow the cleaner’s directions.
• After flushing, fill the radiator with clean soft water and antifreeze until the level is just below the radiator cap.
• Install the radiator cap securely, then fill the recovery tank up to the “H” mark.
• Run the engine for a few minutes, stop it, let it cool, and check the recovery tank. Add coolant if needed.

For coolant choice, see the coolant type guide and the coolant cross-reference guide. Kubota says not to mix coolant brands or types.

• Opening temperatures for the BX23S, B2601, L2501, L3901, L4701, M5-111 and M7060, and the printed manual page for the BX figures.
• Housing bolt torque for any model, and which way the thermostat faces. Check your workshop manual.
• A Kubota bleeding procedure, a bleed screw, or an instruction about running without a thermostat.
• The gasket for the BX2680 and L4701, and the thermostat gasket 16851-73270 that appeared on our earlier page.
• Dealer-versus-DIY cost figures, failure rates and replacement intervals, which were removed because we had no source.