Series 50 – Section 27.4 Defective Coolant Hoses

Section 27.4
Defective Coolant Hoses

To determine if defective coolant hoses is causing high engine coolant temperature, perform the following: ‪

1. Visually examine cooling system hoses; refer to OEM guidelines.
   1. If cooling system hoses are not soft, deteriorated, or collapsed, check the fan belts; refer to "27.5 Fan Belts Are Incorrectly Adjusted" .
   2. If cooling system hoses are soft, deteriorated, or collapsed; refer to "27.4.1 Coolant System Hoses Replacement" .

Section 27.4.1
Coolant System Hoses Replacement

Perform the following steps to resolve worn or damaged coolant system hoses:‪

1. Remove and replace damaged or worn coolant hoses as necessary; refer to OEM guidelines.
2. Install new coolant hoses as necessary; refer to OEM guidelines.
3. Verify replaced coolant system hoses; refer to "27.4.1.1 Test Engine with Replaced Coolant Hoses" .

Section 27.4.1.1
Test Engine with Replaced Coolant Hoses

Perform the following to determine if the new coolant hoses resolved high engine coolant temperature: ‪

1. Start and run the engine.
2. Run the engine through its operating range with no-load for approximately 5 minutes, allowing the engine coolant to reach normal operating range, and visually examine replaced hoses for any leaks.
   1. If the engine coolant temperature is 88-96°C (190-210°F) and no leaks are found, no further troubleshooting is required.
   2. If the engine coolant temperature is 88-96°C (190-210°F) and leaks are found, repair leaks; refer to "27.4.1 Coolant System Hoses Replacement" .
   3. If the engine coolant temperature is not 88-96°C (190-210°F) and no leaks are found, check fan belts; refer to "27.5 Fan Belts Are Incorrectly Adjusted" .
3. Shut down the engine.