Changing Turbo...what I've learned
dbpulvino at hotmail.com
Sat Aug 18 12:28:00 EDT 2007
After finishing this project last weekend, wanted to air the couple
of things I figured out...
Most of the bolts were surprisingly easy to both get at and loosen.
Those krauts must have used some amazing anti-seize compound or
something way back when they made this thing. Yes, one of the bolts
at the turbo to downpipe flange is smaller (15mm vs 17mm), but not
tough to get at and loosen.
The ones that's the bitch is the top left bolt between the turbo and
the manifold (as you face the engine from the passenger side while
standing up). It's a 15mm, but access is nigh on impossible. There
is not enough room to get a socket, or the closed end of an end
wrench on there. Trying to use the open end of an end wrench is just
as problematic as the angle from which you can get at the bolt
positions the wrench in a manner that as you turn it, the outside of
the wrench hits the flange going to the manifold from the turbo.
What I figured out was using a crows foot, I was then able to put a
19mm open end wrench on the drive portion of the crows foot, and
loosen the bolt with the wrench jutting from between the main
downpipe run and upper flex-coupling attaching to the waste gate.
Between that combo and a bike cone wrench, I finally worked the bolt
This brought on the second problem. As you back off that nut, it
runs into hot side turbo housing. That's when I figured out the flex-
coupling had to be removed from the downpipe at it's "down-stream"
side to allow enough movement in the exhaust to get that bolt off the
stud. Of course, before getting into all of this, removing the
airbox and heat shields are paramount.
So now the car is running, the turbo is back on and I've got a head
full of more Audi 200 related mechanical trivia. Did this work in
solving my problem?
To recap, the problem is/was excessive oil consumption (1qt/500-
miles); smoke on startup; and billowing clouds of oil smoke upon
starting to move after idling for more than about 15-minutes. The two
competing theories were valve stem seals or turbo seals. I started
with the turbo after inspecting the intake path, finding quite a bit
of oil in the hose between the turbo and the intercooler, the
intercooler, and the michelin man hose; noticing free-play in the
turbo shaft; and finding the car didn't smoke on startup after
cleaning these pathways of oil. After getting a new car, I also
found the 200 would still smoke on startup after sitting for several
weeks. Thinking on this second data point was in that period of time
(1-2 weeks), given that the engine is not vertical, oil that seeped
past the stem seals would have had ample opportunity to go right past
the pistons and rings into the crankcase. It all seemed logical.
That said I began to have doubts when I noticed the replacement turbo
I'd received, one removed after 90k miles, had about the same
freeplay in the turbine shaft as my turbo...but felt a little more
confident when I noticed upon removal of the old turbo there was oil
on the coldside turbo output path, but on the intake side of the
Back to the "did it work" question. So far I'd say no, as the other
day on my first trip with the new turbo got that same smoking after
idling condition. Ironically, this smoking happened after sitting,
and waiting for my chance to take an emissions test. Car passed with
flying colors, then as soon as I pull off that lot notice the
familiar haze. Luckily for me, I found enough humor in that irony to
avoid the frustration the continuing problem presents. On the bright
side, for some reason oil pressure has gone down since installing the
new turbo, and the new turbo seems to spool up faster. The first I
can objectively measure, the second may just be me justifying.
While it's possible some oil was getting past the seals in the old
turbo, and I will see overall consumption drop, the main thing I was
trying to alleviate in this endeavor (billowing after idling) has not
been solved. As of yet, haven't driven enough miles to see where
consumption is at.
My new working theory; must be the stem seals/the head. Perhaps
while idling for long periods of time, the oil that does get past the
stem seals winds up accumulate in the cylinder during this high-
vacuum/low turbulence state. Step on the gas, turbulence goes up to
level sufficient to make the accumulated oil airborne, and I get to
play James Bond during rush hour traffic.
Hopefully, this information will at least prove beneficial to others
down the road, and feel free to interject with theories as seen fit.
More information about the 200q20v