George Russell's Hungarian GP Power Unit Change: Water Leak, No Penalty, and a Season of Reliability Woes

During the closing moments of Q3 at the Hungarian Grand Prix, George Russell's Mercedes W17 suffered a critical water leak that triggered a chain of events culminating in an overnight power unit change. Here is a full breakdown of the incident, the team's response, and how it fits into Russell's season-long reliability troubles.

What started the chain of events

During Q3 of Hungarian Grand Prix qualifying, Mercedes detected a loss of water pressure on George Russell's W17. The team instructed him to stop on track as a precaution once his final flying lap was completed . After the car was recovered and inspected back at the garage, Mercedes found damage to the Internal Combustion Engine (ICE) caused by the water leak. That damage forced the team to replace the entire power unit overnight .

Precautions Mercedes took

• Immediate on-track instruction: Rather than risk catastrophic engine failure, Mercedes told Russell to park the car at Turn 1 after his last lap instead of driving it back to the pits .
• Full power-unit change: The team opted to fit a completely fresh V6 engine (ICE) for race day rather than attempting a repair .
• Move to 4th unit of the season: This power unit became Russell's fourth of the 2026 season, which is still within the regulated allocation, so no further restrictions apply .

Grid position and penalty status

• Grid position: Russell originally qualified 7th. However, teammate Kimi Antonelli received a 3-place grid penalty for impeding, which promoted Russell to 6th on the grid .
• Penalty status: The power-unit change did not incur a grid penalty. Because Russell was moving to only his fourth ICE of the season — within the allowed limit under F1's 2026 PU regulations — the change was permitted without a drop .

The water leak in the broader reliability context

This water leak is the latest in a string of power-unit problems that have plagued Russell's 2026 season.

• Silverstone (British GP): Russell retired from the lead fight on Lap 34 due to a water leak, though Mercedes confirmed the engine was salvageable and could be reused later .
• Spa-Francorchamps (Belgian GP): Russell suffered a mysterious deployment/power glitch that contributed to him qualifying half a second behind Antonelli, and was then taken out on Lap 1 of the race. Mercedes initially blamed the glitch on Russell's driving style before later identifying it as a software control issue in the power unit .
• Hungaroring: Despite Mercedes publicly expressing confidence that the software glitch was resolved ahead of Hungary , a new physical water-leak problem emerged in qualifying — this time causing internal damage to the ICE and requiring an overnight swap .

In total, Russell has now had three distinct power-unit incidents across three consecutive race weekends (Silverstone, Spa, Budapest), spanning two different failure modes (software deployment glitch and physical water/coolant leaks). While Mercedes believes the software issue is now fixed, the recurrence of a water leak — after a similar issue ended his British GP — points to an unresolved mechanical vulnerability in his PU allocation .