[200q20v] Don't replace that alternator!

[david_haupt at agilent.com]

Oliver,

Unless that shop REALLY knows the 200 Quattro, they might have mis-diagnosed
the problem.  I'm a little surprised nobody else has mentioned this up to
this point, because the topic's been discussed here by several people who
were taken for an alternator when they didn't need one.

FIRST - There is a "welded" connection in the wire going from the battery to
the engine compartment.  It's buried in the passenger side footwell.  Scotty
Mockry's website has a good write-up on how to test for this problem, and
how to fix it if you have the problem.  See
http://www.sjmautotechnik.com/elec.html#chg.  In fact, you should read that
entire page, so you understand all of the things that can go wrong other
than the alternator.

SECOND - Even if it's the alternator, you don't have to replace it.
Alternator rebuilders install new brushes, rectifiers, regulators and
bearings.  I've never spoken to a rebuilder who goes so far as to rewind the
rotor, because those so rarely fail, and it's a labor-intensive operation.
The first three items (brushes, rectifiers, regulator) come as a single
assembly made by Bosch, and it's cheap - I paid $35 for mine.  It also
requires no special tools to replace.  Two machine screws hold the assembly
on the outside of the alternator - you don't have to disassemble the
alternator to get to it.  Bearings, on the other hand, I don't mess with. I
don't have the proper bench and press to do them.  I've never heard of
alternator bearings failing suddenly - they start whining, groaning,
squealing, or otherwise making noise.  

I replaced the brush assembly (with rectifier & regulator) in my old 5000,
leaving the bearings alone.  70,000 miles later, the bearings started
groaning, and I had to replace the entire alternator.  I found that
acceptable, especially since my first repair was at 80,000 miles.  I almost
doubled the mileage before paying full price for an alternator.  I put a new
brush assy in my 1989 200TQ about 18 months ago.  Works fine, but of course
a year and a half is not long enough to tell anything about long-term
success.

R&R on the alternator was a pain, in my estimate.  All the belts come off,
then a bracket between alternator and A/C compressor, and in my case (your
1991 is different) a cooling hose for the alternator, coming from the front
air dam.  The alternator is stuck right in front of the turbo, and some of
the big turbo hoses are in the way.  I didn't need any special tools, just a
fair amount of patience.  It took me two hours to get it out, and I'm slow.
It took 30 minutes to get it back in.  Definitely replace all the belts
while you're in there - you have to remove them anyway.  And don't start
this job until you've read the notes on the rather unusual toothed-gear
tensioner for the alternator.  You can damage it if you attempt to adjust it
incorrectly.  Also, I have never found an aftermarket supplier of the
alternator belt that really had the right size.  Close is not good enough;
get it from your Audi dealer.

You're in Denver, which thankfully has lots of good Quattro shops.  For the
brush assembly, I'd go to your nearest Napa store (Pep Boys and Checker are
unlikely to have the Bosch part).  There are LOTS of regulator assemblies
for these, and the counter person is likely to ask you "which one?".  Bring
the model number of the alternator, and the part number from the old brush
assembly with you.  Best is to match the old brush PN, if you can.  If you
can't, select a brush assembly for the 110 Amp alternator that has a 13.7 to
13.9 V regulator in it (you select them via regulated voltage, as well as
current capability).  Because the battery is so far from the alternator, you
don't want a lower voltage regulator.

My 1989 has a 90A alternator in it.  It's really not enough.  On a cold,
rainy day, a ten mile drive is not enough to recharge my (brand new)
battery.  I've actually considered upgrading to the 110A alternator in mine.
So if you do choose to buy an alt, don't try to save by getting the 90A.

Good luck!

Dave




>and here is the bad news, just had a call from werners... they told me the
>alternator needs to be replaced, the car would now start after fully
>charging the battery.
>cost for alternator replacement is around $450 plus towing & initial
>diagnosis $130.
>
> I browse thru Blau and they offer for my cars model & year 1989 audi 200
>
>bosch $235.00 115 amp
>          $199.0    90 amp
>WAWD/GMG $ 179
>Core $75/$100
>
>can i use the 90 amp instead of the 115amp, what's the diff?, what about
the
>WAWD brand?, is it good.
>
>is it easy to install my self?, or can an ordinary shop/repair can install
>it. the labor is killing me.
>
>i had the battery disconnected tonight so as not to discharge the battery
>again and take home the car tommorow and do the repair myself. kinda
feeling
>mcGyver - necessity is the mother of everything.
>
>
>Oliver M. Llenado
>805 Dahlia Street, Apt 22
>Denver Colorado 80220
>Telephone (303) 322-6613
>Homepage http://www8.ewebcity.com/omllenado