ISC, ISCe, QSC8.3, ISL, ISLe3, ISLe4 and QSL9 Engines – 200-003   Flow Diagram, Cooling System

Table of Contents

General Information

General Information


Internal Engine Coolant Flow, All Applications


Never operate the engine without a thermostat. Without a thermostat, the coolant will not flow to the radiator, and the engine will overheat.

NOTE: The thermostat flow shown is not for QSL9 keel cooled engines. On QSL9 keel cooled marine engines, the thermostat is located in the keel cooled thermostat housing. See flow diagram below.

  1. Coolant inlet from radiator
  2. Water pump suction
  3. Coolant flow through lubricating oil cooler
  4. Block lower water manifold (to cylinders)
  5. Coolant filter inlet (optional)
  6. Coolant filter outlet (optional)
  7. Coolant supply to cylinder head
  8. Coolant return from cylinder head
  9. Block upper water manifold
  10. Thermostat bypass
  11. Coolant return to radiator

All Applications

  1. Turbocharger coolant supply
  2. Turbocharger coolant drain

QSL9 with Keel Cooled (Engine Coolant)

  1. Engine coolant return from keel cooler
  2. Keel cooler thermostat housing
  3. Engine coolant to aftercooler
  4. Aftercooler
  5. Engine coolant through marine gear oil cooler
  6. Engine coolant to water pump
  7. Engine discharge to keel cooler thermostat
  8. Engine coolant to keel cooler
  9. Cooling system housing vent line
  10. Expansion tank
  11. Engine coolant from engine to turbocharger
  12. Turbocharger turbine housing
  13. Exhaust manifold
  14. Engine coolant return from exhaust manifold to water pump.

QSL9 with Heat Exchanger (Engine Coolant)

  1. Coolant from thermostat to heat exchanger
  2. Heat exchanger
  3. Coolant return from heat exchanger to water pump
  4. Turbocharger coolant supply from cylinder block
  5. Turbocharger with water cooled turbine housing
  6. Water cooled exhaust manifold
  7. Coolant return from exhaust manifold to water pump
  8. Turbocharger coolant vent line
  9. Exhaust manifold coolant vent line
  10. Cylinder head coolant vent line
  11. Expansion tank
  12. Coolant makeup to water pump from expansion tank.

QSC8.3 Engine Coolant

  1. Coolant from thermostat
  2. Heat exchanger coolant inlet
  3. Heat exchanger coolant outlet
  4. Water pump coolant inlet from heat exchanger
  5. Water pump coolant inlet from exhaust manifold
  6. Expansion tank
  7. Coolant vent line from cylinder head to expansion tank
  8. Coolant vent line from exhaust manifold to expansion tank
  9. Coolant vent line from turbocharger to expansion tank
  10. Turbocharger coolant inlet from cylinder block
  11. Coolant from turbocharger to exhaust manifold
  12. Expansion tank fill cap.

QSL9 Sea Water Cooled (Heat Exchanger), Marine Applications

  1. Sea water pump inlet
  2. Sea water pump
  3. Sea water pump discharge to fuel cooler
  4. Fuel cooler
  5. Aftercooler sea water inlet
  6. Aftercooler
  7. Aftercooler lower zinc anode
  8. Aftercooler upper zinc anode
  9. Aftercooler sea water outlet to marine gear oil cooler
  10. Marine gear oil cooler sea water outlet to heat exchanger
  11. Heat exchanger
  12. Heat exchanger zinc anode
  13. Exhaust elbow
  14. Sea water discharge.

QSC8.3 Sea Water Cooled (Heat Exchanger), Marine Applications

  1. Sea water pump inlet
  2. Sea water pump
  3. Sea water pump discharge to combination marine gear oil and fuel cooler
  4. Fuel cooler
  5. Marine gear oil cooler
  6. Combination marine gear oil cooler and fuel cooler discharge to aftercooler inlet
  7. Aftercooler
  8. Aftercooler discharge to heat exchanger
  9. Heat exchanger/expansion tank assembly
  10. Heater exchanger discharge to exhaust elbow
  11. Exhaust elbow
  12. Sea water discharge.

Last Modified:  07-Dec-2009