Operation and maintenance manual

Troubleshooting Symptoms Charts QSB4.5 and QSB6.7
Page TS-12 Section TS - Troubleshooting Symptoms
Coolant Loss - External
Cause Correction
STEP 1
Coolant level is below specification
.............
Inspect the engine and cooling system for external
coolant leaks. Repair if necessary. Add coolant.
Refer to the OEM service manual.
OK
Go To Next Step
STEP 2
External coolant leak
.............
Inspect the engine for coolant leaking from hoses,
draincocks, water manifold, jumper tubes,
expansion and pipe plugs, fittings, radiator core,
air compressor and cylinder head gaskets,
lubricating oil cooler, water pump seal, cylinder
block, and OEM-mounted components that have
coolant flow. Refer to Section A.
OK
Go To Next Step
STEP 3
Radiator cap is not correct, is malfunctioning, or
has low-pressure rating
.............
Check the radiator pressure cap. Refer to the OEM
service manual.
OK
Go To Next Step
STEP 4
Cooling system hose is collapsed, restricted, or
leaking
............. Inspect the hoses. Refer to Section 4.
OK
Go To Next Step
STEP 5
Coolant fill line is restricted or obstructed
.............
Check the coolant fill line for restrictions or
obstructions. Refer to Section 7.
OK
Go To Next Step
STEP 6
Coolant is rusty and has debris
.............
Drain and flush the cooling system. Fill with correct
mixture of antifreeze and water. Refer to Section 7.
OK
Go To Next Step
STEP 7
Engine is overheating
.............
Refer to the Coolant Temperature is Above Normal
- Sudden Overheat or the Coolant Temperature is
Above Normal - Gradual Overheat symptom tree.
OK
Go To Next Step
STEP 8
Contact a Cummins® Authorized Repair Facility