McLaren explains Alonso Friday F1 test issue

McLaren has confirmed the issue that forced Fernando Alonso to park up after just one hour of running on the final day of Formula 1 pre-season testing in Barcelona on Friday.

Following a difficult week that saw Alonso lose the majority of his running on Wednesday to an oil leak, McLaren hoped to recover some of the lost time on Friday with the Spaniard behind the wheel ahead of the season-opener in Australia on March 25.

However, Alonso's car came to a halt on only his seventh lap of the day, forcing him to park up at Turn 7 and the session to be stopped as he awaited recovery.

Asked by Crash.net about the issue, McLaren racing director Eric Boullier confirmed that a turbo problem had forced Alonso to park up.

"We had a turbo issue this morning which was related actually to the chassis oil leak we had on Tuesday, a consequence if you want," Boullier said.

"This is now under investigation. We have changed the PU, so the car is running now. We try the fastest way to get ready.

"During the servicing last night, they found a problem with the turbo so they put the turbo back from Tuesday on this engine last night that’s why."

Boullier added how McLaren's push for an aggressive car design had made cooling the car difficult, but was happy with the adjustments that had been made.

"We had an ambitious design, so we had to work with the time we were on the track and not in the garage to try to understand the cooling," Boullier said.

"I think we did a race simulation yesterday without any issues. We are running now, and there are no issues any more.

"So I think we have adjusted our cooling and our needs to the car. So far it works."

Alonso managed to return to the track four hours after the issue, and has completed 34 laps at the time of writing.