146-0240 (1460240) Caterpillar Coolant Temperature Switch (Normally Closed Type)—used to monitor engine water temperature; it opens the circuit when the threshold is reached, triggering a high-temperature alarm or protection mechanism. I. Core Basic Information

Part Number: 146-0240 (1460240)

Type: Normally Closed (NC) Coolant Temperature Switch (Non-continuous signal sensor)

Brand: Caterpillar

Function: Opens the circuit when the water temperature reaches a preset value, triggering the dashboard high-temperature warning light or the engine overheat protection system.

II. Key Specifications

Electrical: 2-pin waterproof connector; compatible with both 12V and 24V systems.

Thread Specification: 3/8"-18 NPT (American National Pipe Thread)

Activation Temperature: Approx. 105°C (221°F); Normally Closed → Open

Operating Temperature Range: -40°C to +125°C

Material: Brass housing + high-temperature-resistant seal; suitable for the harsh operating conditions of heavy machinery.

III. Primary Compatible Engines

3126, 3176C, 3406E, 3412E

C7, C9, C11, C13, C15, C18, and other electronically controlled engines.

IV. Primary Compatible Equipment

Excavators

312D, 314D, 315D, 320D, 323D, 325D, 330D, 336D, 345D, 349D, 374D, 390D

Wheel Loaders (Most Common)

938G, 950G/H, 962G/H, 966G/H, 972G/H, 980G/H, 988H, 994F/H

Off-Highway Trucks / Dozers / Motor Graders

785B/C/D, 789, 793D/F, 797B; D6R, D7R, D8T; 12H, 140H, 160H

V. Alternative Models

146-0241 (Same series; Normally Open [NO] type) 231-2999, 256-6453, 343-5084 (Common OEM Replacement Part Numbers)

VII. Common Faults and Replacement Guidelines

Fault Symptoms

Water temperature is normal, but the high-temperature warning light remains constantly lit (switch contacts are stuck/welded, preventing disconnection).

Water temperature is excessively high, but the warning light does not illuminate (switch circuit is open/broken, preventing closure).

The engine enters overheat protection mode without apparent cause.

Replacement Guidelines

Perform removal and installation only after the engine has cooled down to prevent burns and coolant leakage.

Clean the mounting hole and apply a small amount of high-temperature-resistant sealant.

Tighten to the specified torque (approximately 25–30 N·m).

After installation, perform a test run to verify that the high-temperature warning function operates correctly.