Experiencing your Mercedes Benz W201, particularly the 190E, creeping past the normal temperature mark can be concerning. Like many owners of these classic vehicles, you might find yourself facing overheating issues, especially in stop-and-go traffic. One owner recently shared their experience with a 1985 Mercedes-Benz 190E 2.3 8V Grey Market model, highlighting a common path of diagnosis and repair that many W201 enthusiasts can relate to.
The owner noticed their ‘Baby Benz’ temperature gauge rising above 85 degrees Celsius in traffic. A quick inspection revealed that the main cooling fan, the large yellow five-bladed fan, was spinning, but not with the forceful speed expected when the engine is hot. This observation immediately points towards potential issues within the cooling system, common culprits in older vehicles like the W201.
Following advice, the owner decided to tackle what seemed like likely culprits: the fan clutch and water pump. Parts were ordered – a water pump from Autozone, an electromagnetic fan clutch, a thermostat, and Mercedes-Benz Blue Coolant. A mobile mechanic was enlisted for the installation. However, during the repair, a hiccup occurred: the factory Engine Cooling Fan Sensor, designed to screw into the original water pump, didn’t fit the new aftermarket water pump, despite it being an exact replacement in theory. This necessitated an additional purchase of a new Engine Cooling Fan Sensor.
After the parts were installed, while the car ran better, the main cooling fan’s performance remained questionable. It didn’t seem to spin at the robust speed that inspires confidence in its cooling ability. This leads to a crucial question for W201 owners facing similar issues: Does the Engine Cooling Fan Sensor located on the water pump directly control the fan clutch engagement, or is there another mechanism at play?
Understanding the Mercedes Benz W201 cooling system is key to resolving overheating problems. In many W201 models, the main cooling fan is indeed operated by a fan clutch, but it’s often a temperature-sensitive, viscous fan clutch rather than an electromagnetic one as mentioned in the original post. This type of fan clutch engages and disengages based on the temperature of the air passing through the radiator. As the air temperature increases, the silicone fluid inside the clutch becomes more viscous, causing the fan to spin faster and draw more air through the radiator, effectively cooling the engine.
The Engine Cooling Fan Sensor on the water pump in a W201 is more likely related to the auxiliary electric cooling fan, if the vehicle is equipped with one, rather than the main fan clutch. This electric fan typically kicks in at higher temperatures or when the air conditioning is running to provide supplementary cooling.
Therefore, if you’re experiencing similar overheating symptoms in your Mercedes Benz W201 190E, consider these troubleshooting steps:
- Inspect the Viscous Fan Clutch: With the engine off and cool, try spinning the main cooling fan by hand. There should be some resistance, but it should still turn. If it spins very freely with little resistance, the fan clutch might be failing. Also, check for any signs of leakage from the fan clutch itself.
- Check the Water Pump: While you’ve already replaced the water pump in this case, a failing water pump is a primary cause of overheating. Ensure the replacement pump is indeed compatible with your W201 model.
- Thermostat Function: A stuck closed thermostat prevents coolant circulation and can lead to rapid overheating. Replacing the thermostat is a relatively inexpensive and common maintenance task for W201s.
- Coolant Condition and Level: Ensure your W201 has the correct type and sufficient amount of coolant. Mercedes-Benz Blue Coolant is the recommended type. Check for leaks in the system.
- Radiator Condition: A clogged or corroded radiator can significantly reduce cooling efficiency. Consider flushing or replacing the radiator if it’s old or suspect.
- Auxiliary Electric Fan Operation: If your W201 has an auxiliary electric fan in front of the radiator, ensure it’s functioning correctly. It should turn on when the engine temperature rises significantly or when the air conditioning is activated. The Engine Cooling Fan Sensor on the water pump is likely related to this fan’s operation.
In conclusion, while replacing the water pump, thermostat, and potentially the fan clutch are good steps in addressing Mercedes Benz W201 overheating issues, understanding the specific cooling system components and their functions is crucial. Focus on inspecting the viscous fan clutch for proper operation and ensuring all cooling system components are in good working order. If uncertainty persists, consulting a Mercedes-Benz specialist or mechanic familiar with classic W201 models is always a wise decision to ensure accurate diagnosis and repair.
