The other F1 engine in trouble

When Fernando Alonso guided the new McLaren-Honda out of the garage shortly after the track opened at Jerez on Tuesday morning, it was not just the excited Spanish fans who were delighted that their man was in action.

The relief on the faces of everyone inside the McLaren garage was clear to see. After two days of deep frustrations, as engineers from the team and engine partner Honda chased glitch after glitch on the new turbo engine, finally its testing programme could start properly.

As Alonso returned to the garage after the installation lap and reported zero problems with car and engine, the confidence grew. Longer and longer runs followed, lifting spirits further.

McLaren took to the track before the sun was fully up on Tuesday © LAT

There was even a brief reason to smile when Alonso, out on intermediate tyres at the same time as Nico Rosberg's Mercedes, set a purple fastest time overall in sector one - offering a glimpse of some real potential in the MP4-30.

Any joy did of course turn to frustration a few hours later when running was curtailed by a parts failure that caused a water-pump leak. But still this was an important step for the new McLaren-Honda era.

Honda's progress this week has been the dominant story of the Jerez test. Interest in the fortunes of one of F1's most iconic team-engine partnerships is immense. That its early efforts stalled so much, leaving it at the bottom of the timesheets on each of the three days so far, has only served to ramp up the attention.

But just because Honda has faced the brunt of the media spotlight does not mean the opposition have escaped their own problems.

Day three at Jerez threw up the first public evidence that Renault's pre-season testing programme has perhaps not had as good a start as it had originally hoped for.

Twelve months on from its famously disastrous debut test for the new V6 turbo, Renault was having a better time, but it still was not trouble free.

With the excitement surrounding Red Bull's camouflage livery on day one, and Daniil Kvyat's wing-less laps on Monday, having died down, a proper day of running for its main team on Tuesday confirmed growing paddock whispers that Renault is still playing catch up in 2015.

Daniel Ricciardo not only lost track time through the need for an engine change, he and fellow Renault-powered Carlos Sainz were adrift of the Mercedes and Ferrari on the timesheets.

Their longest stints also seemed quite short compared with what rivals were doing.

It all fitted in with a pattern that team members have hinted at: the two Renault teams being limited in how long they could eke out their long runs amid concerns about a reliability Achilles Heel.

Engine problems have limited Red Bull's testing progress again this year © XPB

Renault's managing director Cyril Abiteboul confessed as much on Tuesday night, as he revealed the French car manufacturer had been braced for a troubled time this week after uncovering a problem in dyno testing last week.

"To cut a long story short, we have a couple of reliability issues and the next few days will tell us if they are big issues or small issues," he told AUTOSPORT.

"They are known issues, so we were coming here with some risk associated to the engine that we knew.

"And so far, some of that risk has materialised. There is one particular issue on something that is even cheaper than your [voice recorder] there! It is crazy that such a cheap part is causing so many issues for a car so expensive like a Renault/Red Bull package."

"It is something that is not critical to performance but can be critical to reliability, so we know what we have to do."

The impact of this part - linked to a metallic shaft that is related to the ERS water pump - was that long runs had to be limited in length, just so regular observations could be made to ensure things did not become critical and lead to an engine failure.

"Let's put it this way: the servicing of the engine has to be pretty frequent," said Abiteboul. "We know what the issue is, we know what we have to do.

"It is a metallic shaft that we have to change, and we have to optimise and review the design.

"It is something that was working very well last year, but we decided to change and improve it a bit further with the overall packaging of the engine to also support Red Bull in their attempt also to have very good packaging. That is why we did not really care for that part.

"Usually you have very specific simulations, designs tests, and validation protocol. But honestly we did not do it for this part because it is such a stupid part..."

The fault with the 'stupid part' was discovered too late for a fix to be in place this week. But a replacement is coming for the next test in Barcelona, which it is hoped will give Red Bull and Toro Rosso a decent step forward.

Ricciardo certainly believed that what is planned for Barcelona cannot come soon enough.

A closed garage has been a familiar sight at Red Bull during this test © LAT

"I think we're where we thought we would be," explained the Australian. "We know there are still some steps for the Barcelona tests. We know there's stuff still to come.

"We didn't expect to have everything on the track this week. Come the next two tests, we want to be racking up more laps, and I think we will.

"We came into this test knowing it was a pretty big evolution from last year, and we knew it would be tight. Obviously we'd love to do 150 laps here, but we knew it would be compromised one way or another.

"I think if Dany [Kvyat] can rack up 50 laps tomorrow, that's not a bad test for us...."

Even with another day to run at Jerez, thoughts are already shifting towards what needs to be done back at base over the next few weeks.