What is the reason for different temperature thermostat

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Discussion Overview

The discussion revolves around the reasons for the availability of thermostats with different temperature settings (50, 60, 71 degrees Celsius) for outboard engines. Participants explore the implications of these temperature variations on engine performance and cooling efficiency.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant notes the existence of thermostats with varying temperature settings and seeks to understand the rationale behind these differences.
  • Another participant questions the comparison being made, suggesting that if thermostats are meant to measure the same parameter, discrepancies could indicate device error.
  • A participant clarifies that the different thermostat temperatures are designed for varying engine loads and cooling conditions, emphasizing the need for efficient engine operation without overheating the lubricating oil.
  • It is explained that the temperature at which a thermostat opens affects engine cooling, with lower temperatures allowing for cooler engine operation. This adaptability is seen as beneficial for changing environmental conditions.
  • An example is provided illustrating how different thermostat settings can maintain optimal coolant temperatures in varying external temperatures, thereby ensuring engine efficiency.

Areas of Agreement / Disagreement

Participants express differing views on the implications of thermostat temperature settings and their effects on engine performance. The discussion does not reach a consensus on the best approach or the reasons for the temperature variations.

Contextual Notes

There are assumptions regarding the relationship between thermostat settings, engine load, and external cooling conditions that remain unexamined. The discussion also does not resolve the potential for device error in temperature measurements.

Who May Find This Useful

This discussion may be of interest to automotive mechanics, engineers working with cooling systems, and individuals involved in the maintenance of outboard engines.

vtr1005
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I am a outboard mechanic, when i change a new thermostat, i find out there have different temperature,

which is 50, 60,71 degree celsius.

can anyone teach me the reason of it?
 
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Different from what?
From each other? Where are they? If they are supposed to measure the same thing at the same place: device error.
 
mfb said:
Different from what?
From each other? Where are they? If they are supposed to measure the same thing at the same place: device error.

I think the OP was asking why thermostats are available for his outboard engines where the thermostat is designed to open at different set coolant temperatures.

The quick answer is it depends roughly on the kind of load the engine will see, and the temperature of the water used to cool the outboard engines. You want the engine warm enough to run efficiently, yet not too warm that the lubricating oil gets too hot and starts to lose viscosity.
 
The different values are the temperature at which the thermostat will start opening, therefore sending hot coolant to the radiator. The lower the temperature, the cooler the engine will run.

It is just easier to change the thermostat when going from a hot environment to a cold one (thus, more cooling from the radiator), than reducing the size of the radiator or the flow of the coolant pump. This way the engine can be kept at the same running temperature no matter the conditions.

For example, say you have the 50°C thermostat and the outside temperature to cool your radiator is 20°C. The coolant temperature at the exit of the radiator might be lowered to 30°C (let say it is the engine designer's intention). But if you use the same engine where the outside temperature is 5°C, the coolant temperature will drop to 20°C at the radiator exit, which might be considered too low when re-entering the engine block. But if you put the 71°C thermostat instead, your temperature at the radiator exit will be back to 30°C.
 
thank you steamking and jack action. I totally understand now.
 

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