Mercedes Power Unit Hardware & Software

[FW17]

Something caused a loss of oil pressure before the blow up

But can it happen do fast?

Oil pressure drop at turn 15, blow-up by turn 1

[Facts Only]

Turbine bearing running at 100,000 rpm a few millimeters away from an 800°c turbine wheel that loses it's oil pressure so no lubrication and no cooling will be dead within seconds (if that).

The internal engine bearings wouldnt last much longer either.

[FW17]

Turbine bearing running at 100,000 rpm a few millimeters away from an 800°c turbine wheel that loses it's oil pressure so no lubrication and no cooling will be dead within seconds (if that).

The internal engine bearings wouldnt last much longer either.

Unrelated question

Do IC and Turbo use the same oil circuit?

[Facts Only]

In my experience; yes.

[mrluke]

People have short memories, how many KERS failures did Nico have during 2014 Abu-Dhabi rings a bell.

How many grid penalties did Ros have for exceeding his PU allocation?

[PlatinumZealot]

That connecting rod bearing that failed in Hamilton's ICE either had manufacturing fault, starved of oil/damaged by debris or it was installed incorrectly...
Overall low oil pressure is unlikely because all the other bearings would turn to sloppy pulp too.

Sabotage is still a possibility at this stage. I know mods don't like to hear until Mercedes explain why the con-rod failed it is still an open case. I think this is heading off-topic so I will stop here.

[NL_Fer]

Could the yellow flames be caused by an broken oil pipe, leaking oil pressure from the supply to the broken bearing?

[basti313]

That connecting rod bearing that failed in Hamilton's ICE either had manufacturing fault, starved of oil/damaged by debris or it was installed incorrectly...

Only the manufacturing fault makes sense. Debris would be collected by the oil filter, installation fault would be immediately visible on the test bench due to friction.

Sabotage is still a possibility at this stage.

No.

Could the yellow flames be caused by an broken oil pipe, leaking oil pressure from the supply to the broken bearing?

No. The flames were caused by a rod going through the crankcase.

[gruntguru]

Overall low oil pressure is unlikely because all the other bearings would turn to sloppy pulp too.

A brief drop in oil pressure is all it takes and a rod bearing is usually the first to go. The process is:
- temporary breakdown of oil film
- temporary metal-metal contact removes some material from the surface of the bearing shell
- Increased clearance means rod can "hammer" up and down on the crank
- hammering increases clearance
- bearing shell begins to spin in the rod (probably)
- repeat last 4 steps until rod breaks (bearing cap parts company with rod) and escapes crankcase area

The other bearings in the engine will exhibit damage ranging from "nothing at all" to severe.

[godlameroso]

Overall low oil pressure is unlikely because all the other bearings would turn to sloppy pulp too.

A brief drop in oil pressure is all it takes and a rod bearing is usually the first to go. The process is:
- temporary breakdown of oil film
- temporary metal-metal contact removes some material from the surface of the bearing shell
- Increased clearance means rod can "hammer" up and down on the crank
- hammering increases clearance
- repeat last 4 steps until rod breaks (bearing cap parts company with rod) and escapes crankcase area

The other bearings in the engine will exhibit damage ranging from "nothing at all" to severe.

Don't forget the possibility of a bearing rotating in it's bore and starving that journal of oil.

[basti313]

Paddy Lowe said they will go for thicker oil, which was used pre Spa. Sounds like they are believing in the overheating theory.

[NL_Fer]

How does a crankshaft oil supply work on a drysump engine? No dipping in the oilbath.

[PhillipM]

It's pressure fed like every other engine. I can't think of many engines less than 100 years old that rely on dipping the crank in the oil sump

[Swobber]

It's pressure fed like every other engine. I can't think of many engines less than 100 years old that rely on dipping the crank in the oil sump

Some lawnmowers

[godlameroso]

How does a crankshaft oil supply work on a drysump engine? No dipping in the oilbath.

Every internal combustion engine used in cars uses a pump, and pressurized oil passages to create a hydrodynamic film between bearing and journal surfaces. The crank and block girdle have machined holes that allow oil to flow from the pump through the tiny clearances between the journals and their bearings. The flow of this pressurized oil causes a hydrodynamic film that prevents metal on metal contact. The bearings have holes that line up with oil passages in their respective bores and journals, if this hole is plugged up by a partially spun bearing it can cause damage in a similar manner as GG described.

A dry sump engine is not too dissimilar to a conventional wet sump. They both supply pressurized oil to their galleries and journals, the dry sump uses a positive displacement pump like a conventional wet sump. The difference is that a dry sump uses an external tank to house the + pressure pump and doesn't rely on a snorkel like a wet sump. Finally the main difference is that a dry sump also uses at least one scavenge pump to return the oil to the tank after it flows out of the moving parts. This has two benefits, first that there is always a supply of oil to the moving parts and ensures that they will not starve of oil due to G-loading. Secondly you can also control the crankcase pressure and mitigate pumping losses to an extent by creating a small amount of vacuum instead of positive crank case pressure.

*Edit:
Having thought about it, I think I know what happened with the Mercedes engine. I have a feeling it's detonation related, the Mercedes burns oil, we've seen the clouds. It's fine if a little oil seeps in while idling but probably not so good while you're pushing hard as oil can lower octane and increase propensity for knock. Oil also has a slower combustion than fuel so it can also cause misfires.