I think i broke a piston ring, what now? :-(

[Scott Fisher]

> So my 1989 200 TQ started seriously smoking in
> Denver last night so I
> retrived today and got it home on the trailer.
> I assume that I have borken a piston ring(s). Its
> smoking very bad!!!! and
> its definately oil.
> So for you grus out there, how should I attack this?

First, make sure you're fixing the right problem.  You
should at very least run a compression test on all
five cylinders, and better still run a leakdown test
if you find a low cylinder.

(Compression test: buy or borrow a compression tester,
stick it in the sparkplug hole, and hold down the gas
pedal while cranking the engine, then read the
results.  I don't know what a 200's numbers should be,
but look for one cylinder that's significantly lower
-- like more than 25% down from the rest.  Leakdown
test: fill cylinder with compressed air, apply gauge,
then see how long cylinder takes to return to
atmospheric.  Longer is better.)

If you DO have a broken ring, you'll very likely have
one cylinder that not only won't hold air, but you may
also be able to feel the air coming out the dipstick
hole as you pressurize that cylinder.  That was the
case on my friend's (non-Audi) race car; he's had
terrible overpressures on a fresh engine, so we did a
leakdown test Saturday and pressurizing the #1
cylinder made an audible whoosh coming out the
dipstick.  (It also showed up as 150 psi on the
compression test, compared to over 200 on the other
three cylinders.)

There is little in the world that makes one feel more
foolish than fixing the wrong problem, particularly
when the fix is expensive, time-consuming, and
physically strenuous, and your car STILL has the
problem.  I learned that lesson after I spent $60 on a
battery and $130 on a new starter, and only THEN found
out that the reason my car wouldn't start was a $9
cable from the battery TO the starter.

Find out what's wrong before you spend a dime.  It
could be an oil line, a head gasket, or various other
things instead of a broken ring.

--Scott Fisher
  Tualatin, Oregon


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