Possible dead engine :( edit: new engine on way :)

[nij]

I had my engine replaced after my first service and it took 6 weeks in total. Luckily, I had an A6 Avant as a courtesy car when it went in for the service. When Audi UK agreed with a new engine, they replaced the dealer’s A6 with one of Audi UK's car (a Q7) for next 5 weeks. I think it is normal procedure for the dealer to investigate the cause before Audi UK will provide a courtesy car, just in case it’s not a valid warranty claim. I would push the dealer to deal with it quicker or provide you with a car though.

[Rs4mar]

I had my engine replaced after my first service and it took 6 weeks in total. Luckily, I had an A6 Avant as a courtesy car when it went in for the service. When Audi UK agreed with a new engine, they replaced the dealer’s A6 with one of Audi UK's car (a Q7) for next 5 weeks. I think it is normal procedure for the dealer to investigate the cause before Audi UK will provide a courtesy car, just in case it’s not a valid warranty claim. I would push the dealer to deal with it quicker or provide you with a car though.

Audi uk have said they can provide me with a courtesy car, but for only 48 hours which I don't think is worth the hassle so I'm pushing the dealer for one ASAP. Trouble is, they ain't being too quick about it

[ArthurPE]

these are my thoughts only

after thinking and talking to a few people (who really know engines) they do not think it is oil related
first, Audi only uses synthetic and a few grades, mostly 5W40 and 5W30 for all cars except say the R8 GT
so the chances of the 'wrong' oil are very small, especially for light service duty and only 3k miles

the failure mode does not jive
there are standard failure modes catagorized for engines that help determine root cause, Audi will tear it down to see if they can correlate

a oil/bearing related rod failure usually snaps or bends the rod from a lateral shear force, ie, bearings drag as crank rotates rod

from the pics this is not the case, the bottom bolted cap pulled off, or was damaged by tension, not shear
force on rod/crank connection
intake stroke, pull on cap/bolts as piston is pulled down by the crank
compression, rod pushes on crank (rod is under compressive force) so no tension on cap
power/combustion, rod pushes on crank, no tension
exhaust, piston starts up with rod under compression, as it approaches TDC it changes to tension and pulls on the cap bolts

the transition from exh to intake is most like where the failure occured
this transition is the highest tension force on the bolts
say a mis-shift occured, and piston speed went from 27 to 40 m/s (8k to 12k rpm or so)
so it goes from 40 m/s up then to 0 and back to 40 m/s down as it reverses direction abrubtly (avg accel of 0), this takes only a few 1000ths of a sec, 12000 rpm ~ 200 rev/sec or 0.005 sec to go up down once 360 deg: the transiton might take, assuming 30 deg of max force per each of 2 transitions = 60 deg/360 x 0.005 ~ 0.0008 sec
a = 20/0.0008 ~ 25000 m/s&2 or 2500 g, that is a lot of force, not to mention the impulse from the accel of the shift from 8k to 12k!
the bolts are fine thread 9 mm iirc, the threads appear stripped out from the pics

this could also be caused by detonation driving the opposing piston down violtently with the resultant torque transferred to the corresponding exh-int transitioning piston

my 2 cents for what it's worth

[ArthurPE]

you can definitely see the cap on the crank end (big end) of the rod is missing
you can see the bolt holes and locating pins

imo a failure due to oil issues would have siezed the crank and broke a rod in the middle
this rod failed at the crank connection, not broke in the middle or at the piston pin

pinGing is Pre-IGNtion (not pinking, unless that is UK jargon) or knocking, firing due to
as opposed to detonation

I dont think Cranks actually seize - the bearings are soft metal (brass or soft steel) so quickly disintegrate causing lots of play in the crank. That's the classic clunking / knocking (not detonation;)) noise of an engine about to go.
Pistons would seize in the cylinder and the Ross would break at the weakest point. I agree this is normally the pins but what I've seen before is when the rod smashes its way through the sump or block it breaks it down even further.

I think the key point is that from that photo it doesn't give a conclusive answer - need to see inside really. Which is why I'm surprised the sump is still in place.

'sieze' doesn't mean lock up
it means increased friction/drag/resistance, and as it heats up it gets worse, tolerances shrink, the bearing material is trapped/compressed between the race/journel and can't escape
and even worse, this debris and no tolerance ihhibits oil flow thru the journel holes

that is EXACTLY the e46 M3 failure mode
bearings were too tight, as they got hot they clamped the rod big end causing drag, as the crank rotated the rod could not keep up putting a shear force on the rod which usually snapped

at first they tried an oil change 5W30 to 10W60, still happened, then an engineering firm/tuner named Nowack id'ed the issued for them
it was made worse by the whip induced by a long I6 crank and high revs

[Rs4mar]

It definately wasn't a mis-shift. If they try to pin a mis-shift on it I will be taking further action.

[adsgreen]

I've yet to see a modern ecu that doesn't log peak rpm. Miss-shift would take seconds to find out. I wouldn't worry so much about that. The first thing try would have done is whacked in Vagcom.

From that picture I don't think anybody can conclusively say one way or the other.
By oil issue I don't just mean wrong grade - drop in pressure or problem on the gallery are possible.
Could be something stupid as crud in the oil pathways wrecking the spray....

Tbh I really don't know but interested in more piccies

[Rs4mar]

Ill be chasing them for more pictures and a update and a courtesy car tomorrow

[ArthurPE]

I've yet to see a modern ecu that doesn't log peak rpm. Miss-shift would take seconds to find out. I wouldn't worry so much about that. The first thing try would have done is whacked in vagcom.

From that picture I don't think anybody can conclusively say one way or the other.
By oil issue I don't just mean wrong grade - drop in pressure or problem on the gallery are possible.
Could be something stupid as crud in the oil pathways wrecking the spray....

Tbh I really don't know but interested in more piccies

the e46 M3 ecu logs certain parameters at 1khz, so it can capture at 0.001 sample rate or so, and it date stamped a peak rpm, throttle % and speed
it also accumulates time >7800 rpm (8000 redline fuel cut-out), mine had ~40 sec in 140k miles or 3500 hours of operation or so
had to be well over 10k in shifts, figuring I hit the rev limiter a dozen times or so, the rest was >7800 but <8000

BMW denied warranty claiming over-rev, I sued and proved otherwise
they can determine several things from these parameters
eg, rpm 8000, throttle 100%, road speed ~65 mph = hit rev limiter in 2nd gear, no bigee
eg, >8500, throttle ~0%, road speed 75 mph = mis-shifted into 2nd instead of the intended 4th

hopefully they will find a defect and make it right

[adsgreen]

I've seen 11500 rpm logged on an engine with fuel cut off on 8000... 5th to 2nd = boom. No arguing out of that one (not me though!)

Whoa- bit optimistic of BMW refusing that far. Bet they hadn't factored in the engineer actor
At least with the rs4 if it happens they may go 'crap- it's that dude from rs246... We can't bullshit this one.. Just pay it'

[PhilT]

Love this thread What excellent support for the OP.

[MikeFish]

Love this thread What excellent support for the OP.

Pah! They're not supporting the OP, they are jsut using it as an excuse to show off thier knowledge of engines. I'm loving it though.

[Rs4mar]

Hi,

What does 'op' mean? Apologies I'm relatively new to the world of forums and still learning the basics.

[scaghead]

Opening poster...I think...as in you fella

[MikeFish]

Original poster, but the point is the same.

[Rs4mar]

Oh ok that makes sense.
Well thank you to everyone for all their support and advice it really is much appreciated Had no more news today but hopefully some more soon