Multiquip 12915549801 Thermostat 55H 4TNV84T-DSA

The Multiquip 12915549801 is a genuine OEM Thermostat 55H 4TNV84T-DSA designed for the STXD6i and HTXD6i hydrostatic ride-on power trowels. As a direct OEM replacement sourced through Multiquip's authorized parts program, 12915549801 is produced to the same specification as the original component installed at the factory. This thermostat is a critical cooling system component — using the correct OEM part helps protect the 4TNV84T-DSA Yanmar diesel engine from thermal damage and ensures consistent operating temperatures during extended finishing runs.

Key Features

• Genuine OEM Cooling Precision — Engineered to open at the correct 55°C threshold for the 4TNV84T-DSA Yanmar diesel, maintaining the engine's designed thermal operating window.
• Direct-Fit Replacement — Matches the original thermostat housing interface on STXD6i and HTXD6i trowels, dropping in without modification to the cooling circuit.
• Confirmed Fitment — Verified for STXD6i and HTXD6i super-sized and heavy-duty hydrostatic ride-on trowels powered by the Yanmar diesel engine.
• Engine Protection Under Load — A correctly functioning thermostat prevents both overcooling and overheating during demanding slab finishing work, where consistent RPM and sustained engine load are the norm.
• Fuel and Emission Efficiency — Proper coolant temperature regulation keeps combustion conditions within the engine's designed range, supporting efficient fuel burn and minimizing unnecessary wear on internal components.

A thermostat regulates engine coolant temperature by blocking or allowing flow to the radiator depending on how hot the coolant gets. When the engine is cold, the thermostat stays closed so the coolant circulates only through the engine block, allowing it to reach operating temperature quickly. Once the coolant hits the thermostat's opening temperature, the valve opens and routes hot coolant through the radiator to be cooled. A stuck-open thermostat causes the engine to run too cold, reducing efficiency and accelerating wear; a stuck-closed thermostat causes rapid overheating and can lead to serious engine damage if not caught in time.

For fitment questions or help confirming compatibility with your machine, contact DHS Equipment directly.

Part Details

Compatibility & Fitment

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.