The MF 65 was built with two engine options and each takes a different thermostat. Most MF 65 tractors in the field are the Perkins diesel version, but check your engine before ordering.
Perkins A4.203 diesel — 180°F thermostat: OEM 1446222M91. Outside diameter is 2.705". Opens at 180°F / 82°C. This number supersedes earlier part numbers 1446073M91, 890991M91, 883471M91, and 1853245M1. Perkins lists it as 2485639. The same thermostat fits the MF 165, MF 255, MF 300, MF 302, MF 304, MF Super 90, MF 1100, and MF 1130.
Continental Z134 gas — 160°F thermostat: OEM 836000M91. Outside diameter is 2.115". Opens at 160°F. Also replaces 830842M91, 836000V91, and 181566M1. Shared with the MF 35, MF 50 gas, MF 135 gas, MF 150, and Massey Harris 50.
Installation notes: The thermostat housing on the MF 65 sits at the front of the cylinder head with two bolts. Drain coolant below housing level first. Clean both gasket surfaces completely — any old gasket material left behind will cause a weep. Set the new thermostat spring-side down into the recess. Torque housing bolts to 15 ft-lbs. After refilling coolant, run the engine until the thermostat opens and top off the radiator. Check for leaks around the housing after the first heat cycle.
Cross-Reference Table
| Supplier | Part Number | Fit | Notes | |
|---|---|---|---|---|
| RAParts | 1446222M91 | Drop-in | 180°F — Perkins A4.203 diesel | |
| Cross Creek | 1446222M91 | Drop-in | 180°F — Perkins diesel, 2.705" OD | |
| Jensales | 1446222M91 | Drop-in | 180°F — Perkins diesel | |
| TISCO | 836000M91 | Drop-in | 160°F — Continental Z134 gas engine | |
| All States | 836000M91 | Drop-in | 160°F — Continental Z134 gas engine |
Specifications
- Notes
- Gas and diesel thermostats are different diameters — not interchangeable. Most MF 65s in service are diesel.
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