Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Engine cooling
The cooling system design is similar to the engine S63. The coolant circuit was redesigned fro increased flow rates for the engine S63 TOP. In addition to the mechanical coolant pump, the engine S63 TOP also has a total of 4 electric auxiliary water pumps.
- One electric auxiliary water pump to cool the exhaust turbochargers.
- Two electric auxiliary water pumps to cool the charge air cooler and Digital Motor Electronics (DME).
- One electric auxiliary water pump to heat the passenger compartment.
Engine cooling and charge air cooling are separate cooling circuits.
A modified geometry of the road wheel for the belt driven coolant pump yields an increased coolant flow rate. The cylinder head cooling circuit could thereby be optimized. An electric auxiliary water pump is installed to enable cooling for both exhaust turbochargers after the engine is shut off. It is also used to support exhaust turbocharger cooling while the engine is running.
In order to warrant sufficient cooling of the charge air, the coolant-air heat exchangers have been enlarged for engine S63 TOP compared to the engine S63. They will be supplied with coolant through an independent cooling system with 2 electric auxiliary water pumps. The coolant circuit for the charge air cooling and Digital Motor Electronics (DME) has a cooler and 2 auxiliary coolant radiators. Heat is taken from the charge air by means of an air-to-coolant heat exchanger for each bank. This heat is then discharged into the ambient air through a coolant air heat exchanger. The charge air cooling has its own cooling circuit. It is independent from the engine cooling circuit.
The cooling module itself is only available in one version. For vehicles with a variant for hot countries and in combination with the optional equipment for maximum speed (SA840) a separate cooler is used (in the right wheel arch).
The following graphic illustrates the cooling circuit.
| Index | Explanation |
|---|---|
| 1 | Coolant temperature sensor at radiator outlet |
| 2 | Filler |
| 3 | Thermostat |
| 4 | Coolant pump |
| 5 | Exhaust turbocharger |
| 6 | Heat exchanger for heating system |
| 7 | Dual valve |
| 8 | Electric auxiliary water pump |
| 9 | Electric auxiliary water pump |
| 10 | Coolant temperature sensor on engine |
| 11 | Coolant expansion tank |
| 12 | Electric fan |
| 13 | Radiator |
The engine S63 TOP has the same heat management as is already known from the motor N55. The heat management includes a separate control for electric cooling elements electric fan, map thermostat and coolant pumps.
The engine S63 TOP is equipped with a conventional map thermostat. Additionally, the opening can be implemented at a lower coolant temperature by way of an electric heater in the map thermostat.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.