Williams Rue Engine Problems

A routine inspection by BMW of Heidfeld's engine prior to Friday practice discovered a defective exhaust valve that may not have lasted the race.

And, with Mark Webber's car having the same problem with his brand new engine, the German car manufacturer decided that both power-units needed changing.

Although Webber has been able to avoid getting a 10-place grid penalty by not running on Friday, ahead of the new engines arriving on Saturday morning, Heidfeld did not have that option because he had already used the power-unit in Imola and so he had to get down to work on Friday.

The fact that Heidfeld did not have to worry about conserving miles on the engine left him free to conduct an extended programme and at least make some progress in finding a good set-up for the car - as was witnessed by him setting the third quickest time.

"Our position looks quite good for the moment but despite this I wasn't completely happy with the balance of my car this morning so we changed a few things around for the afternoon and I was definitely happier with it," said Heidfeld. "In fact we made some good steps forward.

"The fact that I am going to change my engine again tomorrow at least allowed me to do more laps than usual as I had to try to cover the programmes for both my car and Mark's car. The only negative thing at the moment is that obviously I will have to start my race from towards the back, due to the penalty."

Webber, who watched the action from the pitlane, said: "It seemed like a pretty good day for the guys and it was good that Nick had a smooth run and completed all of our programmes. I 'll start with my job on track tomorrow and I'll try to catch up and get the most out of this weekend for qualifying and the race."

BMW are due to dyno-test the two new engines at their Munich headquarters on Friday afternoon before flying them down to Barcelona where they will be fitted to the Williams cars before Saturday's final free practice sessions.