Gates 33556 Engine Coolant Thermostat

Gates OE Type Thermostat for Mercedes-Benz Cooling Control

The Gates 33556 engine coolant thermostat is built for precise temperature regulation and an OEM-equivalent fit in select Mercedes-Benz applications. It is a direct replacement for vehicles that need stable coolant flow control, including Mercedes-Benz 300SEL and 380-series models.

Key Features

• OE Type Thermostat for factory-style cooling system operation
• Reverse poppet bottom-blocking by-pass design for proper coolant routing
• Start-to-open temperature: 167°F / 75°C
• Steel and copper construction
• Jiggle pin weep hole included for air bleeding during service
• OE Performance comparison rating
• Gates part number 33556

Product Details

Gates OE Type Thermostat 33556 is engineered for accurate coolant temperature control and leak-free fitment in select Mercedes-Benz 300SEL, 380SE, 380SL, 380SEC, 380SEL, 380SLC, 500SEC, and 500SEL applications. The reverse poppet bottom-blocking by-pass design helps maintain the correct coolant path as the engine warms up, supporting consistent operating temperature in older Mercedes-Benz cooling systems. This thermostat uses steel and copper materials and includes a jiggle pin weep hole for easier air purging during installation and service.

This part cross-references Beck/Arnley 143-0412 and Motorad 248-160 for the same application.

What It Helps Address

• Engine running too cool or too hot
• Slow warm-up after cold starts
• Temperature fluctuation during driving
• Cooling system flow control issues
• Replacement needs for aging Mercedes-Benz thermostat housings and cooling service

Installation Notes and Tips

Verify the thermostat orientation, bypass design, and temperature specification before installation. Clean the housing sealing surfaces thoroughly and inspect the cooling system for corrosion, debris, or worn hoses before reassembly. This thermostat does not include an installation tool, so use the proper service tools for your vehicle and follow the factory cooling system procedure. Confirm fitment by year, model, and engine application before ordering Gates 33556.

Quality Assurance

Gates OE Type Thermostats are built to deliver precise temperature control and OEM-equivalent fitment standards. The 33556 is specified for direct replacement use in select Mercedes-Benz cooling systems, with materials and design chosen to match OE-style service requirements.