Cummins/Onan GTA14 / GTA14 qi 20 NA — Thermostat Replacement

Repair & overhaul

For the Cummins/Onan GTA14 / GTA14 qi 20 NA, from the Cummins/Onan owner's manual.

Applies to: Cummins/Onan GTA14 qi 20 NA, Cummins/Onan GTA14 engine

Procedure

1. Disconnect negative battery cable and drain cooling system below thermostat housing.
2. Remove four cap-screws attaching thermostat housing to rocker housing.
3. Remove thermostat housing from water transfer tube.
4. Remove four thermostat cover cap-screws and remove thermostat from cover.
5. Install thermostat in cover; clean gasket surfaces and install new gasket.
6. Install thermostat cover and four mounting cap-screws.
7. Install thermostat housing assembly and mounting gasket.
8. Inspect transfer tube o-ring; install four mounting cap-screws and washers.
9. Install upper radiator hose, fill with coolant, start engine and check for leaks.

Full service-parts list: Cummins/Onan GTA14 qi 20 NA →

Source: Cummins/Onan owner's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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