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 13-4.
Figure 13-4
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 rpm.
[a] If a balanced coolant flow is observed in the sight, call Detroit Diesel Customer
Support Center (313-592-5800). Shut down the engine.
[b] If a balanced coolant flow is not observed in the sight glass, refer to section 13.10.1.
Shut down the engine.
13.10.1
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 section 13.10.1.1.
13.10.1.1
Test Engine with Resolved Radiator Coolant Flow
Perform the following to determine if thermo-modulated fan replacement resolved high engine
coolant temperature:
1. Refer to section13.10 for the exhaust caution before proceeding. 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.
[a] If the engine coolant temperature is 88-96°C (190-210°F), no further troubleshooting
is required. Shut down the engine.
[b] If the engine coolant temperature is not 88-96°C (190-210°F), shut down the engine.
Call the Detroit Diesel Customer Support Center at 313–592–5800.
