Cooling System: Notes
The cooling system of the N55 is enhanced with additional oil cooling.
Two different types of oil cooling systems are used depending on the model and application. In the "hot climate" version, heat transfer from the engine oil to the engine coolant is avoided by separating the oil cooler from the engine coolant circuit. The other version uses an auxiliary radiator in combination with an oil to coolant heat exchanger bolted to the oil filter housing. The auxiliary radiator enhances cooling efficiency by adding surface area to the cooling system.
INDEX EXPLANATION CHART
| Index | Explanation |
|---|---|
| 1 | Radiator |
| 2 | Engine oil to air cooler (hot climate version) |
| 3 | Heater coil |
| 4 | Characteristic map thermostat |
| 5 | Electric coolant pump |
| 6 | Exhaust turbocharger |
| 7 | Heating heat exchanger |
| 8 | Coolant valve |
| 9 | Oil-to-coolant heat exchanger |
| 10 | Coolant temperature sensor |
| 11 | Engine oil thermostat (hot climate version) |
| 12 | Expansion tank |
| 13 | Coolant level switch |
| 14 | Equalization line |
| 15 | Auxiliary radiator |
| 16 | Electric fan |