Mercedes has revealed that their engines were overheating during Friday running in Mexico. The German manufacturer struggled throughout the day, strangely ending the day as the fourth fastest squad behind Red Bull, Renault and Ferrari.
Mexico City's high altitude makes it harder for the engines to breathe, which puts extra strain on them. Mercedes technical director James Allison explained after Friday running the issues that the Silver Arrows had, which perhaps partly explained why there was such a big pace deficit.
“This is an unusual track, which places unusual demands on the chassis, power unit, cooling systems and tyres," he said. “From all our running today, we have to conclude that we have not yet found the best way to meet those unusual demands with good performance on both single laps and in the long runs.
“We were overheating the power unit in a number of areas today, and that meant we had to protect against this by turning it down as a precaution. With a bit luck, and no little hard work, we can get ourselves into better shape tomorrow and on Sunday, when conditions are also forecast to be cooler. We have plenty of work ahead of us overnight and in FP3 tomorrow to put ourselves in a stronger position than we were able to achieve today.”
Driver Valtteri Bottas added: "Both of the compounds started to grain quickly and it feels like we're lacking overall grip, so the car is sliding around a lot which is then wearing the tyres.
“We don't have a definite answer why the pace isn't quite there yet; we're going to have to analyse it and look at it from every angle. We have plenty of work to do for tomorrow and, while we are scratching our heads a little at this point, I'm confident that we'll find answers over the course of the evening and come back stronger tomorrow.”
Bahrain International Circuit - Winter testing