The Genie 77478GT is a genuine OEM Thermostat designed for Perkins 104-22 engines powering Genie S-series telescopic and Z-series articulating boom lifts, including the S-40, S-45, S-60, S-60 HC, S-60 TRAX, S-65, S-65 TRAX, Z-45/22, Z-45/25, Z-45/25J IC Power, Z-45/25 IC, Z-45/25J IC, and Z-60/34. As a genuine OEM component, this thermostat is built to the same specification as the part that left the factory, ensuring proper engine temperature regulation from the moment it is installed. Cross-reference part number 77478GT against your Genie parts manual to confirm fitment for your specific machine serial number before ordering.
Key Features
- OEM-Calibrated Opening Temperature — Manufactured to the exact wax-element specification of the original Perkins 104-22 thermostat, so coolant flow transitions at the correct temperature every time.
- Direct Drop-In Replacement — Matches the original housing diameter, bypass port orientation, and sealing flange of the Perkins 104-22 cooling circuit for a straightforward swap with standard hand tools.
- Broad Boom Lift Coverage — Fits Genie S-series telescopic booms and Z-series articulating booms equipped with the Perkins 104-22 engine, spanning the S-40 through S-65 TRAX and Z-45 through Z-60/34 families.
- Protects Engine from Thermal Stress — A correctly functioning thermostat keeps the engine in its optimal operating range, preventing the overheating and cold-running wear that lead to premature cylinder and head damage.
- Critical to Safe Aerial Operation — Engine overheating on a boom lift can trigger unexpected shutdowns at height; replacing a failed thermostat restores the thermal protection the engine needs to run through a full shift.
A thermostat is a temperature-sensitive valve that sits between the engine and the radiator in the cooling circuit. When the engine is cold, the thermostat stays closed, keeping coolant recirculating within the engine block so it reaches operating temperature quickly and evenly. Once the coolant hits the thermostat's design-rated opening point, the valve opens and allows hot coolant to flow through the radiator to be cooled. When a thermostat fails stuck-open, the engine runs chronically cold and burns fuel inefficiently; when it fails stuck-closed, coolant cannot reach the radiator and the engine overheats rapidly — both conditions accelerate wear and can cause unplanned shutdowns on Perkins 104-22 powered boom lifts.
Part Details
| Part Number | 77478GT |
|---|---|
| Brand | Genie |
| Part Type | Genuine OEM |
| Description | Thermostat (Perkins 104-22) |
Compatibility & Fitment
| Name | Model |
|---|---|
| S-60 | S-60 |
| S-65 | S-65 |
| S-60 HC | S-60 HC |
| S-60 TRAX | S-60 TRAX |
| S-65 TRAX | S-65 TRAX |
| S-40 | S-40 |
| S-45 | S-45 |
| Z-60/34 | Z-60/34 |
| Z-45/25 | Z-45/25 |
| Z-45/25J IC Power | Z-45/25J IC Power |
| Z-45/25 IC | Z-45/25 IC |
| Z-45/25J IC | Z-45/25J IC |
| Z-45/22 | Z-45/22 |
Verify Before You Order
Fitment is machine-number and revision-specific; always confirm your model and serial number against the fitment list.
Why Buy From DHS Equipment
Every part is verified against the manufacturer's part number before it ships, so what you order is what arrives. We carry parts from leading OEM brands and our own DHS Quality Parts line of professional aftermarket components. Need help finding the right part? Our team is available to confirm compatibility whenever you need it. Orders are processed fast to keep your jobs on track. We don't just sell parts. We keep you jobsite ready.
Questions? Contact our team at [email protected] or 866-611-9369 — DHS Equipment is here to help you maintain peak performance.
