Mercedes C320 Oil Cooler Leak
What We Found and How We Fixed It
A 2007 Mercedes-Benz C320 recently came into the EU Auto workshop with a persistent oil leak and a noticeable smell of burnt oil under the bonnet. The owner had seen oil spots appearing on the ground and had to top up the oil between services. We began with a detailed inspection to identify the source.
About the C320 and the M272 V6
The 2007 C320 features the M272 3.0 litre V6 engine. It is a strong and well-regarded engine that was widely used across the Mercedes range. Like many engines, however, it has a few known weaknesses. One of the most common is failure of the oil cooler seals.
The oil cooler sits deep in the centre of the engine between the cylinder banks. When the factory seals age and harden, oil begins to escape and pool in the valley of the engine. If this is left unresolved, it can lead to:
Burning smells caused by oil contacting hot surfaces
Oil contamination throughout the engine bay
Loss of oil pressure
Accelerated component wear
Potentially significant repair costs in the long term
Addressing this issue early prevents more serious damage.
What Our Inspection Found
A visual inspection and dye testing confirmed an active oil leak from the oil cooler area. Oil was present in the V of the engine which is a clear indication that the cooler and seals were no longer functioning correctly.
The repair is complex due to the cooler’s location under several critical components.
What We Replaced and Repaired
To carry out the repair properly and replace all affected seals, our team completed the following work:
Removal of the EGR valve
Removal of the fuel rails
Removal of the intake manifold
Removal of the turbocharger
Cleaning of oil and coolant contamination
Installation of a new oil cooler and upgraded seals
Reassembly with new gaskets and correct torque specifications applied
Full post repair inspection and testing
We completed a pressure test and a road test and confirmed that the leak had been fully resolved.
The End Result
The C320 is now running cleanly with no further leaks detected. With issues like this addressed promptly, the M272 engine is capable of very high mileage and strong long term reliability.
Need Help With Your Mercedes
If you own a Mercedes C Class or any model equipped with the M272 engine and have noticed:
Oil spots under the car
An oil smell when the engine warms up
A drop in oil level between services
Grease or oil residue behind the intake area
It is best to have the issue checked by a technician who is experienced with European vehicles.
EU Auto specialises in Mercedes diagnostics, repairs, and maintenance with a high standard of workmanship and without dealership pricing.
EU Auto
42 Edward St, Perth WA
Independent Mercedes Specialists
https://euauto.com.au/
Contact us to arrange an inspection and keep your vehicle running at its best.
