[Biturbos4] Some words on K03 destruction (Was: 2000 S4 Running Hot)

r harout carrera3_2 at yahoo.com
Tue Aug 30 11:52:00 EDT 2005

Thanks! I'm even more nervous now becasue that oil light came on when I was stuck in traffic and the car started to heat up. It honked at me 4 or 5 times...but then when the car got cooler, it stopped. It hasn't beeped or lit up since then.
I hope it was just the heat causing a false alarm. if the oil pressure was low still, the light would pop back on right?
PS. I really can't afford K04s! Not even sure if I can afford anything having to do with this car!
stco <keman at interwolf.net> wrote:
IMO, dino oil changed out every 3-5k is probably sufficient so long as you
take your time letting everything cool down before shutting it off, ie:
easy on the throttle for that last mile or so, let it idle for a minute or
so. I'd say that's even more important with dino than synthetic, simply
because dino has less ability to resist high heat.

That being said, the simple ~60 second cooldown cycle of just being easy
on the throttle in that last mile or so is IMO *CRITICAL* to the turbo
life. It cannot be overlooked, not even once. This goes beyond any coolant
afterrun circuits ability, and even a turbo timer might not be enough to
save the day. I'll try to explain why..

Many of us at the shop would stand around and chat about what could be the
cause of the 2.7T's to lose their turbos, especially in S4's vs. A6 2.7T's
and Allroads. The conclusion usually was hot turbine shut-down. KKK K03's
are a little thinner in the turbine shaft (it's some strange internal heat
transfer shape) than K04's. The thought is if you shut the turbo down when
it's VERY hot ... it actually sags a little, bending under it's own
weight. Because of the speed and ultra precise balance necessary for these
turbos, even the tinyest bit of sagging is enough to throw the thing out
of balance. Then the following occurs: a high speed harmonic vibration
sets up, and the locknut holding the compressor turbine backs itself right
off. We'd find them either laying in the intercooler if the turbine
managed to slingshot it past, or just laying in the intake elbow. The
wheel immediately falls off and destroys itself, or starts to fall off and
destroys itself. OR the bearings simply wear out because of the lateral
forces and the oil seal goes. Any # of possible failures, all because of
that harmonic vibration.

The other avenue of turbo destruction is oil starvation because of a
crusted up and clogged oil feed line. Audi did change the oil feed line
mid model year to combat this. But as I said above, this isn't the only
type of failure, so with it or not you're not immune. This type of failure
won't have the locknut laying in the intercooler, the turbos bearings just
give up the goat, the compressor wheel strikes the housing, it makes a
really loud siren sound and you know the rest...

A note on turbo lubrication: If the 1.8T's can suffer no turbo failures
aside from OIL STARVATION from CHUNKS of burned oil clogging the oil
pickup screen because they run 3.7 quarts of dino oil for -10 thousand-
miles (per scheduled maint) ... the 2.7T's can run dino oil for every 5k,
surely. Without a doubt. Those 1.8T's didn't even lose their turbos,
usually .. it was the cam bearings first, and then the con rod bearings,
and then the turbo would let go if the person refused to stop driving
despite that no oil pressure warning glaring them in the face. (Not low
oil level, but zero oil pressure)

Will your engine be as sparkling clean inside with a dino oil like as if
you ran a synthetic? Definitely not. Will your gaskets be more likely to
harden up a little sooner and start leaking earlier? Probably. But ..
catastrophic turbo failure cuz of regularly changed dino oil? Nah.

Just my 2 cents..

And OBTW, if you can afford K04's ... why are you even asking the
question? Do it! :)

I've got an '88 Thunderbird turbocoupe as my winter beater that I recently
upgraded sufficiently to run 19 psi of boost. Words do not describe the
terror and humor that this POS produces. More boost = more fun^2 (And yeah
I know my S4 rocks in the snow but people here in virginia get snow so
rarely that they tend to rear-end everything in sight and I'd rather it be
my $1k beater mobile than a car costing 50x that)

- Keman

On Mon, 29 Aug 2005, r harout wrote:

> so let me ask a question (nervoulsy)
> How likely is it that I was have catastrophic turbo
> failure if the car has only run with regular oil--but
> chnaged frequently?
> Inevitable? What are the signs? I will use Mobil 1
> moving forward, but the owners before me did not.
> Maybe I should order the K04s now so I get them in
> time for failure!

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