SI20.10-P-0002A | Service Information: Check function of coolant thermostat | 15.11.11 |
ENGINE 266.920 /940 /960 /980 in MODEL 169
ENGINE 266.920 /940 /960 /980 in MODEL 245
P20.10-2225-01
1 Hot water hose (to heater heat exchanger)
2 Coolant hose (to vehicle radiator)
In the event of complaints regarding too low coolant temperature when driving (coolant temperature gauge in the instrument cluster) the function of the coolant thermostat can be checked as shown in the following table.
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If after at least 5 minutes, but after a maximum of 10 minutes engine running time there is a temperature difference from the hot water hose to the coolant hose of at least 20 °C, the coolant thermostat is OK and does not have to be removed.
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| Checking | ||
Requirements | The engine is in the cold condition. The vehicle and engine have ambient temperature. | ||
1 | Start engine | Engine at idle. | |
The settings of the heater operating unit and blower stage are not relevant for the test. | |||
| Measure | ||
2 | Measuring point of hot water hose (1) | Above the connection fitting of the thermostat. | |
3 | Measuring point of the coolant hose (2) | At half the distance between the thermostat and vehicle radiator. | |
Measured value | Engine running time: min. 5 min....max. 10 min. | ||
Temperature difference: 20 °C | |||
Temperature measurement gotis://G_58.3_12.0 |