#F1 Forensics: The data behind Rosberg’s engine failure


Brought to you by TJ13 contributor Tourdog

Rosbergs Roast at the end of the Monza race is only the second major failure that Mercedes has had this year. Both Lewis and Hulkenberg had Control Electronics failures at the first two races, but those were easily replaced, and went on to cover 7800 and 7100 Km respectively.

The first real failure was on Hulkenberg’s car, which occurred in China. Nico H started the next race in Bahrain with his 2nd ICE, Turbo, MGU-H and MGU-K, which tells us he most likely torched them all in China.

Rosberg’s failure at Monza was a lot less than surprising. Not only has Nico amassed the most laps run of any driver, with 1,864 (across all PU’s), but he also had the second highest mileage on his second PU of any driver. Hulkenberg has the most, but that is because the total failure of his First PU forced him to use his second for practice sessions all season.

My estimations are that Rosberg had 3263 Km on all 6 components of his PU when it failed. Those are hard kilometers too. Nico was using PU #1 for practice sessions since Austria, (he changed to PU #2 in Canada along with the others), and so this PU has mainly been used for Qualifying and Races.

You can see a breakdown of the component use in the Chancery’s Archive.

Another bit of interest is the lap times from Monza. You can see all of Nico’s times in

which posted yesterday, but here is a breakdown of the final few laps.

So, lets look at the now infamous radio call to Lewis:

“Ok Lewis we’re gunna go Strat mode 3, strat mode 3. We need to pull a gap, we need to pull a gap, don’t ask questions, just execute.”.

That went out sometime before lap 48, when it was broadcast on the FOM feed. We can assume the same call went out to Nico, as he would have been in the same position. If the stewards were about to potentially add 25 seconds to his time, every second he can gain could potentially save him a position, and curtail the potential loss of points.

If you study the times, you can see that on Lap 46, both Nico and Lewis started “turning up the wick”, so this is probably when the radio call came in.

Sebastian must have gotten that call relayed to him as well, because on the same lap his times fall.

On Lap 46 and 47, Nico and Lewis up their pace, with Lewis putting in a stormer on lap 48, of 1:26.672.

Nico’s lap times start increasing on lap 48, instead of decreasing, and go up further on lap 49 and 50, loosing almost half a second a lap. Then on lap 51, it lets go. It seems that pushing a well worn ICE was just too much, and Nico payed the price.

The other factor we should mention, is fuel.

Being that the new PU’s Mercedes brought to Monza used a completely different fuel blend, it is possible there was contamination when the fast swap was done. Mercedes did not have time to swap out fuel cells, nor completely purge the fuel system between FP3 and Quali. The compounds in the new blend may have had a negative interaction with the old ICE’s internals, further expediting Nico’s failure. It goes beyond just fuel however. Lubricants play a larger and larger part in the performance of these Engines. It is possible there was further contamination in the oil system or any number of other systems that were modified to accommodate the new unit.

In reality the choice to swap out Nico’s PU seems rather strange. Mercedes claimed they had some kind of “failure”, but then post race said it was merely a coolant leak. Granted the leak may have been difficult to find, and could have been internal, we don’t know, but the choice to do a complete PU swap in the short time between sessions Saturday seems riskier than troubleshooting and repairing the new unit.

Being that PU #3 was probably installed and tested over a week ago, and then only run in FP sessions, there shouldn’t have been any problems. My tinfoil hat is telling me there were other factors at play here.

12 responses to “#F1 Forensics: The data behind Rosberg’s engine failure

  1. “Granted the leak may have been difficult to find, and could have been internal, we don’t know, but the choice to do a complete PU swap in the short time between sessions Saturday seems riskier than troubleshooting and repairing the new unit.”

    Err, coolant leaking in to the internals is usually a terminal failure for an engine.

    In a run-of-the-mill road car, yes, you may take the internals out and rebore/skim the damaged surfaces and fit new bearings etc., but for an F! engine it is likely to be an extensive repair – assuming that any idea of a repair is even going to be contemplated.

    • You are right Craig, except we know the leak wasn’t internal, because Mercedes has since come out and said that PU#3 will be fine to use at the next race. IF the coolant leak was in the ICE, it would be garbage, as the teams are not allowed to break the seal, and any coolant sitting inside the engine block, even for a day, would do enough damage to write off any F1 engine. It would also necessitate a full tear down to verify, which Mercedes would have had no time to do properly between then and now, so how can they already be sure?

      This is what bothers me. I am not ready to start shouting conspiracy, but the swapping out of a brand new PU between FP3 and Quali is almost never done unless there is absolute catastrophic failure.

      • Last I read it was a coolant leak into the oil system. Now in theory this could be the auxiliary tank in which case they may have gotten away with it, but otherwise it looks like some serious damage will have been done to the ICE, guess it depends on if it was spotted before the oil started to circulate.

        Mercedes line is still about being unsure whether the PU can be resurrected for Singapore. Time will tell!

  2. “Mercedes sabotages the car of the driver who has been getting his behind kicked all season long, so as to favour the one doing the kicking….”

    Yup really tinfoil hat wearing weather we’re having here….

  3. The main reason for the failure was that Merc turned the engine up to full power in order to catch Vettel. Confirmed by Toto Wolff and reported this morning in AMuS and MST. The engine was simply too old to take the beating. According to Wolff there were no prior warning signs, it simply went boom.

  4. “Sebastian must have gotten that call relayed to him as well, because on the same lap his times fall.” – Why?

    By the way, I think people exaggerate how much faster Mercedes got all of a sudden. Gap was 22.2 at lap 46. It became 23.3 at lap 48. By 52nd lap, it was 24.1. 2 seconds in 6 laps? It’s not like he pulled half a second gap every lap….

    • Why? Because Ferrari can hear Mercedes radio messages. When Ferrari heard Merc tell their drivers to up the pace and build a gap for apparently no reason, they surely would have responded.

      “It’s not like he pulled half a second gap every lap….”
      If you go back and look at the first part of the race, .5 a lap is almost exactly what Hamilton was pulling on Seb, in fact near the end of the first stint is actually more than that. You can see all the lap times for both drivers in my article “Italy Top drivers lap times”.

  5. @Tourdog I was my understanding that Nico’s updated PU was changed out for an older one as there had been a cross-contamination of fluids that would have eventually led to a catastrophic failure had they continued to run it further into the weekend. Now we have engine coolant, engine oil, hydraulic oil, ancillary coolents and possibly different types of lubricant for say the turbo compared to the best lubricant for the big end bearings and pistons, so there are obviously seals that stop the lubricants and coolents mixing, some of these may be deep in the bowls of the unit and if it is thought that there is where the failure lies, then they wouldn’t have a) had the time to do an engine strip down and rebuild and b) they build these engines in clean rooms with specialist equipment and I should think that when stripping down the engine, certain parts may need to be replaced with new just because you can’t trust them to still be in pristine condition, such as piston rings, all internal seals and gaskets. If a team has no intention of stripping an engine to it’s based components and then rebuilding it at the track, then they won’t be carrying the spare parts, or the personell who have the level of skill in that exact discipline. Hence why they changed the engine for the one they had the track with least mileage on it, or the only other engine at the track, we may never know.
    But I think that explains the logic behind the Mercedes team decision.

    • You make some valid arguments, and may well be correct.
      What really bothers me, is that they went back to an old engine.
      There is a video somewhere I watched in the last year, that was an interview with the Ferrari fluids guy from Shell. He showed the inside of the truck, some of the equipment they used, etc. I remember him saying that based on the element content in the oil, they could pretty much predict the end of life for an engine. He even gave an example that they had predicted the end of life of one, so the team swapped it, and then that engine failed on the bench a very short time later.

      So a couple points:
      Merc knew that engine was near end of life, as I said it had a lot of KM’s on it, and they were hard KM’s.
      There is no way Mercedes brought 2 brand new PU’s to the race, and didn’t bring at least a 3rd as backup.
      There are only 7 races left, and Merc still has one more PU to install without penalty.
      The car was already set up to use the new fluids, and they were pressed for time.

      I just can’t figure out why they wouldn’t install another new PU (#4). They must have known the old one would be slower, and more likely to fail.
      Now Nico has lost PU#2 completely, thanks to the Italian Marshall’s letting it burn while hanging 10 feet in the air.
      He only has #1 left to use for practice, and that PU has over 5000 Km on it, and probably cannot be pushed very hard at this point.
      So Nico is going to have to use his Race PU for practice WHEN #1 lets go.
      Why didn’t they install #4?

      Like I said, it’s bothering me.
      But I am open to a good debate..

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