replacing a 1990 CQ's Pressure Accumulator (long)

[schulz@iatcmail.ed.ray.com (Peter Schulz)]

I took yesterday off, with the intent of replacing the Pressure
Accumulator or "bomb" in my 1990 Coupe Quattro. 

If you don't own a CQ, you can delete this message...

I ordered the part a few weeks ago from Linda at Carlsen Audi.
I supplied her with the VIN number to make sure that I got the
right part....(she had THE best price, by far!)

So guess what happened...

Using Scott J's and Al Powell's tips, I went ahead with the removal of
the old bomb.  With the ignition off, I pumped the brake pedal 40 or
so times  (overkill...the pedal lost pressure at less than 5 pumps)

I previously sprayed the brake and hydraulic fitting with "Liquid wrench".
Put the car up on jackstands, and removed the left front tire for 
better access.  Removed the belly pan (3 x 10 mm sheet metal screws)
removed the 11 mm brake line with a 11 mm flare nut wrench.  Then I gently
pushed the line out of the way.  I removed the top hydraulic line, which 
goes to the steering rack (hose clamp).  I let the pentosin drain into 
a liter soft drink bottle, then clamped off the end.  Next, I removed the
lower mounting bolt for the bomb.  Then I tried to remove the 17mm banjo
nut bolt with a 17 mm flare nut wrench.  That's when the trouble started.
The bomb rotated every time I tried to do this, so I remount the lower 
mounting bolt.  The bomb still rotated.  So I then put a 1/4 inch nut driver
into the brake line hole in the bomb, and wedged the end against the engine
block.  That "cracked" the 17mm bolt loose, and gouged my wrist...Loosened
the lower mounting bolt and slipped the bomb out of it's mount.   

I then compared it to the replacement part : 893 612 061 D.

Oh oh...the bomb that I removed was an A.  The high pressure hydraulic line
opening (banjo) on the A is larger than that on the D.  The openings on the
D version appear to be the same size, too. $@%!$#%!#$!%#%$!%$

I called Carlsen...according to my VIN, I should be using the D (newer) bomb.
But wait, there's a * in the sequence numbers for the VIN...Evidently my CQ, 
has the VIN of the late 1990 CQs, but had the early parts....^@#%$^@%^  
The A in my car has since been superceeded by "C".

So I cleaned the old bomb, and re-installed it.  Reinstalled th tire.
Filled up the hydraulic reservoir with 2/3 liter of Pentosin 7.1.  
Started the car, turned the steering wheel lock -to - lock 6 times 
to bleed the system.

The new bomb (the D) goes back to Carlsen today for an exchange.

Lessons learned:

1.) Don't trust the Audi fiche when it comes to VIN sequence numbers.  If possible,
get the part number of the old part!

2.) Use 11 and 17mm flare nut wrenches or you will strip the bolts!

3.) You need to do something to prevent the bomb from rotating when removing the
17mm banjo bolt for the high pressure hydraulic line.  The mounting bolt only
prevents vertical, no rotational motion.  Putting thr nut driver into the brake
line opening worked for me, but I risked damaging the opening's threading.

More bad news...I broke the sensor in the penstosin resevoiur cap...Now the 
brake light flckers whenever the car hits a bump in the road....

Good news.  The next time that I do this, I'll be able to do it in a half hour!

Hope this will help any Coupe Quattro owners nearing bomb replacement!

And thanks again to Scott and Al for their tips!

Peter Schulz
1990 Coupe Quattro (late model with airbag, but with the tubular exhaust manifold)
schulz@ed.ray.com