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Re: Brakes - Jesse & Tom

Tom - from your responses, I guess you're not in the states - but I'
m not sure what currency you're citing....I hope that you have the 
chance to find a less expensive parts supply.  My comments follow...
> > Am I confused?  I thought you had already replaced the bomb.  If 
> > so...........
> > 
> No, I haven't replaced it. I seriously doubt that it is the culprit. I
> checked this morning and I got a good 80 hard pumps before the pedal
> got stiff. This after the car had been sitting idle all night.

In that case, I **doubt** it's the PA!
> The light comes on also after a few (2 - 4) good rocks on the steering
> wheel.

HAH!  Possible evidence of hydraulic pressure problems.

  Try running the 
> > engine with the brake off, and see if the light goes off - and 
> > whether a quick pump or two on the brake makes it light up again.
> >  
> Around 10 - 12 good pumps with the engine at idle.

> > > My VAG dealer wants SEK 4.5K (~ US$ 700)!
> > 
> > For what part?  The hydraulic pump?  If so, WAY too much.  You can 
> > get one rebuilt for under $200.
> > > 
> Naw, for the PA. The last time I had a rebuilt pump it was around SEK
> 2.5K (~US $ 385) that was a few years back.

YIPES YIPES YIPES.  You should be able to buy a rebuilt for under 
$200 - and you CAN buy a rebuilt hydraulic pump, if you need one, for 
under $200.  I'm installing one on my 1990 200 later this week.  Got 
it from AudiOnly for $185 (US), I think.

> > PS: I'm waiting for a new supply of lifeblood (Pentosin) from 
> > AudiOnly (for about $8 per liter!).  When I get it, I will replace my 
> > hydraulic pump.  I have made my own pressure gauge to replace Audi 
> > part #1441 and will post about the four-month diagnostic process I've 
> > done - but I want that stuipd pump to be in place and be 100% sure the 
> > problem is finally dead, with a stake thru its heart!!
> > 
> I bought a liter yesterday at SEK 163 (~ US $ 25) ...

Again - I have bought a ton of this stuff at $22/liter.  I just found 
out this week that I can buy it from Peter at AudiOnly for $8/liter.

In case it helps - here's his full address, etc:

Peter Coulter
1582 South kenton St.
Aurora, CO  80012
Toll-free in US: 800/962-1902
Regular number: 303/367-4341
Fax:  303/338-0942

OK - here's the way I recommend you work this out.  In the Bentley 
manual, they have a whole section on the hydraulic system.  Finding 
the culprit is difficult because of the interaction of PA, pump, and 
brake servo.

I fought a brake warning light for four months, and feel that I now 
have it licked - but am wtiaing to install the pump and prove it.  
The first thing that happened was Iack of brake assist, which 
required a new brake servo ($600 at a dealer - nevermore).  But the 
warning light still came on.

So I changed the PA.  Twice, each time with used/tested parts.  After 
the second time, I decided maybe it wasn't the PA...or maybe it still 
was.  The warning light came on INSTANTLY when I hit the brakes.  But 
the brakes always worked just fine.

So I began to suspect the pump.  While having a dealer do some tests, 
they commented that the pump showed 1800 psi.  Spec is 2200+
psi.  So I went to a machine shop, had them build me a tool with a 
3000 psi gauge and 2 feet of 5000 psi hose, terminating in a 1/8" NPT 
fitting.  A machine shop ran a 10 mm x 1.0 pitch die over the 
fitting, converting it to the 10 mm x 1.0 thread required to screw 
into the brake servo port which holds the brake light warning switch. 
This made it a substitute for VW tool 1441, and cost about $40 - 
less than the dealer would charge to check it.  Not only that, but 
the length of the fitting was almost identical to that of the brake 
warning light switch; with the addition of a copper washer, it 
screwed right in and held pressure!

I went through the whole sequence of tests outlined in the Bentley, 
and the results were that:
a)  It took a long time for the pump to build pressure
b)  Pressure never reached the 2200+ psi required; max was 1900 psi, 
and most times I couldn't get over 1800
c)  Pressing the brake pedal caused an immediate pressure reduction 
of 300 psi on the first pump, then a diminishing amount of pressure 
loss for each successive pump (200, 125, 80, etc.)
d)  The system could not restore pressure promptly after the brake 
pedal was pressed in (c).
e)  There is a pressure test to determine the low-pressure faloff of 
the PA.  I could not GET mine to exhibit a pressure falloff at all.  
I interpreted this as meaning it was OK.

Based on the above, I concluded the pump was bad and that I could 
stop messing with PAs.  I bought one from AudiOnly but ran out of 
Pentosin so I'm waiting for it to come in.

SO - if you can reason it out, great.  If not, I recommend building a 
gauge - and conducting your own tests.  Any good hose/hydraulic shop 
can make the gauge and hose you require.  If you're in metric 
country, you should be able to get the fitting required - if not, 
convert it as I suggest above.

If you have questions, holler back.