Mercedes is confident in the reliability of its new power unit after an investigation in to Nico Rosberg's issue ahead of qualifying at Monza.
Rosberg was forced to revert to an old specification of power unit after final practice on Saturday morning, replacing the upgraded engine which Mercedes had introduced for the Italian Grand Prix. Team-mate Lewis Hamilton retained the new unit and qualified on pole position, and the team's investigations have revealed no reliability concerned with Hamilton's specification.
"Overnight investigation has revealed the cause of Nico Rosberg's problem in Italian Grand Prix FP3 yesterday," Mercedes tweeted on Sunday morning. "This was traced to a leak in the cooling system which contaminated the Power Unit, not a problem with the engine itself.
"The Power Unit will be inspected in the coming days to decide if it can be used again at future races."
Rosberg will start from fourth on the grid behind Hamilton and the Ferrari pair of Kimi Raikkonen and Sebastian Vettel, and he admits he is at a disadvantage using an old power unit.
"It is a lot of mileage, it has done 6 races and engines degrade over time, so it has definitely compromised my weekend and it will compromise my race as well. It is obviously from the data that the laps are good, but I lose a lot of time on the straights, so that makes it difficult."
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