[s-cars] P/S flushing procedure

[Fred Munro]

Thanks for the write-up, Igor - this job is on my "to-do" list. The bomb on
my UrS4 leaks down a bit overnight - takes about 20 seconds to clear the
light in the morning. If it sits for a few hours, the light goes out
immediately on start-up. If it sits for a couple weeks, it takes 30-40
seconds to clear the light.
Sounds like you've got a leaky bomb check valve or a leaky brake servo.

Fred Munro
'94 S4


-----Original Message-----
From:	KBATTPO [SMTP:igor at s-cars.org]
Sent:	Wednesday, May 15, 2002 3:33 PM
To:	Richard Beels
Cc:	s-car-list at audifans.com
Subject:	Re: [s-cars] P/S flushing procedure
<snip>
>  >>>

Thanks Richard for forwarding this to me.

In the UrS it is even much easier than in the 200. I have just done it.
Perhaps Jimmy would want to archive this procedure.

1. Lift up the front of the car on jack stands.
2. Wrap a plastic bag over the lower intercooler to crossover pipe hose.
You don't want this sticky fluid cover your beautiful blue Samco hose
with a messy gunk.
3. Undo the 7 mm hose clamp at the rear of the bomb. Surprise, but there
was no Oetiker clamp on mine. Prolly coz I had the bomb replaced under
warranty a year ago.
4. Pull off the hose and catch the old fluid in a suitable wide
disposable container. I found that cut in half an empty gallon container
for the windshield washer fluid serves perfectly well. The fluid will
drain for a while. And yes it is going to be black and have dark specks
suspended.
5. Now you can undo the P/S reservoir cap. Remove the cylindrical
plastic insert with the steel mesh and clean it up with the brake or
carb cleaner.
6. Slide the reservoir up off its holder so that the lower return hose
is not kinked. This will allow you to drain the reservoir completely.
7. Spray some brake cleaner into the reservoir to remove the deposits
from its bottom and let it drain into the container.
8. Ask an assistant to turn the steering wheel (the engine is NOT
running!!!) several times lock to lock to evacuate the remainder of the
fluid from the steering rack. It will take at least 10 cycles.
9. Place the return hose back onto the bomb nipple and tighten up the
hose clamp.
10. Slide the reservoir down back into its holder. Insert back the
plastic cylinder.
11. Pour about 1L of hydraulic fluid into it until the level is at MAX.
12. Turn the steering wheel several times lock to lock quickly to bleed
13. Start the engine and run it for about 2 minutes. The bubbles will be
coming out of the reservoir. Keep an eye on the fluid level and DO NOT
let it run dry or you WILL destroy the P/S pump.
14. Shut off the engine. Top off the reservoir to the MAX line.


Now, a few observations.
1. With no residual pressure in the sys upon the start up it took the
pump 40 seconds to extinguish the light! Does my pump work properly? It
was replaced under warranty about a year ago.
2. After the pressure has been built up (the light is out) it took 10
quick foot stabs to bring the light back on. Is this what you see folks?
3. After the engine had been shut down it took 39 pumps for the pedal to
go hard. At least the bomb is holding the pressure.
4. If the car sat on the lot for an hour or two, there is no residual
pressure and the whole light concert started over again. Is this what
you see folks?

Igor
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