Hydraulic Pump Fixed

[SJ]

Symptoms:
Uh oh, a new development.

Wife left this morning in the 100q, heading for the mall. I saw a liquid
trail out of the driveway. Something is leaking badly.
I called her on the cell phone, and got the location of her car. Drove to
the mall with all the standard audi liquids in the trunk.
The pentosin reservoir was almost empty. I filled it, and drove the car back
home. Checked reservoir at home and it was just a wee bit down. Not sure if
anything leaked out as there might have been air in the system when I filled
it up at the mall.

The hydraulic pump caps have been leaking and bubbling for about a year now.
Nothing major though.

I suspect the cold weather(twas nippy last night) shrinks the cap O-ring
seals enough to cause a major leak when cold. The leak seals up when the
pentosin warms up and swells the cap seals..

Another project for me.
==========================================================

***** I did a quickie repair on the hydraulic pump -- only changing the
X-cap O-rings.

Interesting observations:

1. Mounting of the O-ring.
The X-cap shoulder area looks more or less like a normal bolt, but with a
large machined shoulder.
On the other hand, the matching bore in the housing has a stepped shoulder.
The lower shoulder is for the O-ring. The upper shoulder is for the outer
half of the wide X-cap shoulder.
When you install the O-ring and screw in the cap, the cap will stop turning
when the bore upper shoulder makes contact with the outer half of the X-cap
shoulder. In other words, the compression on the O-ring is determined purely
by the dimensions of the bore shoulders. The 37 ft lbs of torque specified
only locks the x-cap in place with no effect on the O-ring.
All the more reason to purchase the correct O-rings, as the sealing
compression force is based on dimensions only. A slightly thinner O-ring
will not seal as well. A thicker O-ring may be compressed so much that it
distorts and gets "squeezed out".

2. X-cap removal issues.
The impact hammer method shown in the Bentley is BS.
Use an air impact gun.
The X-cap head is recessed in the bore. Thats right, the head is halfway
buried in the bore. Rust will seize up the X-cap head making extraction
impossible even with an air gun - you will cam out the X-cap..
The solution is to heat the X-cap with a torch. Not enough to make it red or
anything . .but enough to cause expansion and a breaking of the rust grip.
I damaged (cammed out) two X-caps before trying out the torch solution. The
caps came out easily after being heated. I had spare X-caps from a junkyard
unit.
I recommend heating ALL the X-caps before removal.

3. X-cap rusted slots
Some of X-caps had badly rusted slots. Dont try to remove X-caps without
first cleaning out the slots.
A wire brush cleaned out most X-caps. I used a dremel tool with a cut off
wheel to clean out the slots in the rusted X-caps.
Test each X-cap with the removal tool before applying any force.. Make sure
the tool bottoms out in the slot.


SJ
85 Dodge PU, D-250, 318, auto
85 Audi 4k - - sold but still on the road
88 Audi 5kq
90 Audi 100q




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