Toto Wolff admits Mercedes have some concerns when it comes the reliability of their F1 power unit after hearing "unusual noises" within the engine.
Lewis Hamilton will serve a 10-place grid penalty for the Turkish Grand Prix after being fitted with a new Internal Combustion Engine on Friday.
This is different to other penalties seen this season, as Mercedes have elected not to change any of the engine ancillary components, such as the Turbocharger or MGUs.
When asked about the matter, Wolff confirmed there are concerns related to the combustion engine rather than the hybrid parts of the power unit.
"Well-spotted. It's tricky, when you start to push the boundaries with power unit performance at a certain stage you will experience some obstacles," Wolff told RacingNews365.com and other members of the media, when asked about the situation.
"Our power units have been the most reliable since the introduction of the hybrid engines in 2014.
"Because these boundaries are being pushed, we have seen examples of unusual noises within the combustion engine that aren't completely understood at that stage yet, and therefore caused some trouble in the past.
"We had engines that basically failed. Now it's about containing the problem. Because in that phase, redesigning parts is not something you would tackle."
With F1 set to introduce an engine freeze next season, Wolff admits it's a top priority for Mercedes to get the issue sorted in the near future.
"I think balancing performance and reliability has always been the key metrics the last couple of years, and it will be going forward," Wolff added.
"We will not be carrying any deficits into next year, because the deficits are being understood. Now it's about finding solutions that contain these."