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MBE 900 LOW COOLANT TEMPERATURE

There are several causes for low coolant temperature. These probable causes are: ‪

  • Faulty Thermostats
  • Insufficient Radiator Air Circulation

Troubleshooting Procedure for Faulty Thermostats

To determine if faulty thermostats are causing low engine coolant temperature, perform the following steps: ‪

  1. Remove thermostat from the thermostat housing; refer to section .
  2. Inspect thermostat for correct operation; refer to section .
    1. If the thermostat is fully open at 95C (203F), check insufficient radiator air circulation; refer to section .
    2. If the thermostat is not fully open at 95C (203F), refer to section .

Thermostat Replacement

Perform the following steps to replace thermostats: ‪

  1. Install new thermostat; refer to section .
  2. Verify replaced thermostat; refer to section .
Test Engine with New Thermostat

Perform the following steps to determine if thermostat replacement resolved low engine coolant temperature: ‪

  1. Start and run the engine.
  2. Run the engine through its operating range with no-load for approximately five minutes, allowing the engine coolant to reach normal operating range.
    1. If the engine coolant temperature is 82-105C (180-221F), no further troubleshooting is required. Shut down the engine.
    2. If the engine coolant temperature is not 82-105C (180-221F), shut down the engine. Check insufficient radiator air circulation; refer to section .

Troubleshooting Procedure for Insufficient Radiator Air Circulation

To determine if insufficient radiator air circulation is causing low engine coolant temperature, perform the following: ‪

  1. Visually examine the radiator and radiator shrouding.
    1. If the radiator has excessive clogging, debris, or dirt, refer to section .
    2. If the radiator shrouding is not damaged, incorrectly positioned, or inadequate, and if the radiator is absent of clogging, debris, and dirt, then call Detroit Diesel Technical Service Group.
    3. If the radiator shrouding is damaged, incorrectly positioned, or inadequate, refer to section .

Exterior Radiator Repair

Perform the following steps for exterior radiator repair: ‪

  1. Clean the exterior radiator of all clogging, debris, or excessive dirt; refer to OEMguidelines.
  2. Verify exterior radiator repair; refer to section .

Radiator Shroud Repair

Perform the following steps for radiator shroud repair: ‪

  1. Repair or replace damaged radiator shrouding; refer to OEMguidelines.
  2. Verify exterior radiator repair; refer to section .
Test Engine with Repaired Exterior Radiator and Shrouding

  1. Start and run the engine.
  2. Run the engine through its operating range with no-load condition for approximately five minutes, allowing the engine coolant to reach normal operating range.
    1. If the engine coolant temperature is 82-105C (180-221F), no further troubleshooting is required. Shut down the engine.
    2. If the engine coolant temperature is not 82-105C (180-221F), shut down the engine. Call Detroit Diesel Technical Service Group.