Series 50 – Section 27.10 Abnormal Radiator Coolant Flow

Section 27.10
Abnormal Radiator Coolant Flow

To determine if abnormal radiator coolant flow is causing high engine coolant temperature, perform the following:‪

1. Install a sight glass with string (both ends) to the radiator outlet hose near radiator and before fill and heater return lines; see Figure "Radiator Flow Check" .
   

   Figure 1. Radiator Flow Check

2. Start and run the engine at full load.
3. Observe the string for flow and direction as well as the fill and bleed lines. Continue observation while varying the engine speed between 1800-2100 r/min.
   1. If coolant flow is not observed in the sight glass an imbalance is not present, call Detroit Diesel Technical Service Group. Shut the engine down.
   2. If coolant flow is observed in the sight glass an imbalance exists; refer to "27.10.1 Abnormal Radiator Coolant Flow Resolution" . Shut the engine down.

Section 27.10.1
Abnormal Radiator Coolant Flow Resolution

Perform the following steps, as necessary, to resolve abnormal radiator coolant flow:‪

1. Correct bleed line size; refer to OEM guidelines.
2. Correct fill line size or connector fitting size; refer to OEM guidelines.
3. Correct restrictive top tank opening; refer to OEM guidelines.
4. Correct location of standpipe; refer to OEM guidelines.
5. Verify repairs made to correct abnormal radiator coolant flow; refer to "27.10.1.1 Test Engine with Resolved Radiator Coolant Flow" .

Section 27.10.1.1
Test Engine with Resolved Radiator Coolant Flow

Perform the following to determine if thermo-modulated fan replacement 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.
   1. If the engine coolant temperature is 88-96°C (190-210°F), no further troubleshooting is required. Shut the engine down.
   2. If the engine coolant temperature is not 88-96°C (190-210°F), shut the engine down. Call Detroit Diesel Technical Service Group.