Car back with new engine fitted

[ArthurPE]

the engine has 60k miles?
those pistons are very clean for that mileage, hardly any coking
one cylinder has no scoring?
did only 1 have it, or more than one?


this failure has zilch to do with carbon
and I'm sure Audi will confirm that

[k3ukr]

Yes just under 60k ,the pics don't show what the eye sees ,pics were taken from iPhone ,on one piston there was det marking round the edge ,I am going to let audi decide that one ,as I said before I have my car back with a new engine I am happy ,I will do 1000 miles then dyno it again and compare the results

[P_G]

Glad you are happy with the end result and Audi looked after you. Like everyone I think we would all be interested in Audi's official findings after they have done their investigation.

[neckarsulm]

This may seem simplistic so forgive me but driving with a misfire can cause long term damage could this be the cause of the problem or just a symptom of the underlying issue and if so how can you tell which?

[ArthurPE]

Yes just under 60k ,the pics don't show what the eye sees ,pics were taken from iPhone ,on one piston there was det marking round the edge ,I am going to let audi decide that one ,as I said before I have my car back with a new engine I am happy ,I will do 1000 miles then dyno it again and compare the results

probably the smartest thing that's been said for a while

looks like the 1 cylinder is bad...looks like the ring gaps did it...
who knows what caused it

I would like to see the valves on a 60k car (uncleaned)
no pics of the valves?

looks like 1 cylinder, they isolated it thru a compression test, and removed the associated head...

only way to find out is to ask them...I actually spoke to them today and mentioned your car and the one in Spain...

they also relayed what they think happened to the car in Australia, and let's just say they do not agree with the owners diagnosis of valve deposits scratching the walls...something distorted the cylinder bores/block...

[ArthurPE]

This may seem simplistic so forgive me but driving with a misfire can cause long term damage could this be the cause of the problem or just a symptom of the underlying issue and if so how can you tell which?

imo a misfire wouldn't do that
plus you'ld have a bunch of codes...

detonation 'might', enough compression could distort/spread the rings and gouge the walls...

it's good Audi stepped up no questions asked...
60k is out of warranty correct?

[ArthurPE]

the cylinders aren't nikasil, petty sure Audi doesn't use that process http://en.wikipedia.org/wiki/Nikasil

they use a different process, 'alusil' http://en.wikipedia.org/wiki/Alusil
basically uses the silicone in the aluminum to do the same thing, rather that nickel...I was told the 'honing' or etching is done by a laser...

“Alusilâ€

[pad125]

I'm keen to know how old your car is k3ukr?

[2manytoys]

I'm interested to hear what they say is the cause too. I was told wrong oil which isn't the case. I'd like to know what else could cause this to happen (apart from wrong oil) so as to avoid it in the future (if possible).

I'm just wondering if the pinging, left too long (as no one knew what it was when it was happening) could cause this. If this is a possible cause, it would be good for Audi to let people know. It seems that once the carbon is really bad the car starts to ping. If the dealers caught it in time maybe this might not happen (but that's only a guess given the wrong oil explanation isn't right either)

[PetrolDave]

Maybe driving the engine hard while the oil is still cold and not properly lubricating the bores could be a factor?

It's real easy to hit the 7000rpm limiter while the oil is still below 60 Celsius since this engine just loves to rev.

[P_G]

I would concur with that Dave. I'm conscious not to rev mine beyond 3500 rpm until the oil temp is 97 degrees C and then it goes into 'S' mode.

A degree of machanical sympathy goes a long way with any car.

[SR71]

So Audi got the design right but the cold rev limit wrong?

If Audi can claim "wrong oil" can cause this kind of damage, what does that mean and what is the mechanism whereby this "wrong oil" does the damage?

Genuinely curious.

[ArthurPE]

running a cold DI engine under high load may induce detonation, cold cylinders
another reason for the rev limit
sustained detonation, ignored, will warp/distort the cylinder in short order...

mis-fire, fuel, no spark/bang
ping or preignition (which timing <beep> can reduce)
detonation

are 3 distinct events, but seem to be used interchangeably...

[aidanjaye]

I reckon the rev limiter is set at 7000 as ifit wasn't, it would take forever for engines in cold weather to reach running temps. And 3500rev limiter may have buses running up your arse as you exit junctions and promptly hit the limiter.

[ArthurPE]

I reckon the rev limiter is set at 7000 as ifit wasn't, it would take forever for engines in cold weather to reach running temps. And 3500rev limiter may have buses running up your arse as you exit junctions and promptly hit the limiter.

even with a 7000 limit, if you apply a heavy load from onset, you will damage the engine...you can't legislate/enforce the application common sense...no such thing as 'idiot proof'...
if someone wants to break something, they will find a way...
build a better mouse trap, and out will come a smarter mouse

my M3 starts at 4000 and gradually works up to 8000...

I've heard from Audi re: the Australian engine

waiting to hear re: the one in Scotland & Spain...

the one in Spain looks like a 'one of', something got into cyl 8...

looks like only one cyl damaged on the Scotland car also
probably did a compression check, and removed that head, they left the other on, why? perhaps no issue?...the car had 60k and the piston tops look great...which cyl no. was the one with the obvious gouges?