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UNauthorized Hyd. Pump Rebuild
Just a note to those of you who are contemplating the rebuild vs. replace
options on the Audi hydraulic pump. I talked with various independents and
dealer service techs and found that the hit ratio ran 50:50 for the
independents, with the dealer types pushing the R&R fix..(imagine my
The biggest complaint was that the pump would continue to leak at the
center Iron/Aluminum interface. I'm sure someone has listed the fix..
somewhere in the archives, (which I have yet to peruse), but on the off
chance that this issue has not been mentioned, here's the deal.
In this case, being forewarned was half the battle. Our '87 5KTQSW had the
rack replaced by the previous owner-God Bless Him-, but the pump was
disgracing itself in public, pissing itself at every opportunity. After
pricing the seal kit vs. remanufactured unit, it seemed to be a no brainer,
but for the aforementioned caveat. For (about) the going price for a can of
the green mystery fluid-which was being consumed at the rate of one every
2-3 weeks, I ordered the seal kit and proceeded to pull the pump on the
first (semi) warm day in January (PA,'86). On disassembly and cleaning, I
thought it couldn't hurt to check the aluminum for distortion. Without
farting around with straightedge and feeler guages, I went straight for the
"lapping plate" a sheet of 1/4" glass with a sheet of 220 grit sandpaper
(soaked in warm water) laid flat. After a few circular passes on the face
of the aluminum, I picked it up and took a look-Big Shock- The whole center
of the casting was low (darker-no sanding pattern), with the edges all nice
and bright. It took about 10-15 min. of hand lapping to bring the whole
surface dead flat, with an even color and pattern, plus an extra minute or
so to tighten up on the depth of the O-ring groove. I thought that the
Iron side would be much more stable, but just for grins, I checked it out
and found more or less the same situation. (Less distortion but more time
to remove the material..Iron is tough stuff.) In both cases, I finished up
with a piece of 440 grit, also wet, to go for the ultra-smooth finish.
After a thorough cleaning to remove all traces of the lapping residue,
everything went back together without drama, just be sure to pre-wet all
O-Rings, pistons and internals with the Green Mineral Oil before assembly.
All this took place in the relative comfort of the unheated basement, so
the real shock didn't come until it came time for installation. Overnight,
a Nor-Easter had hit, dumping about two feet of (Hurricane level) windblown
snow, necessitating pressing the Quattro into immediate service. When I
could (finally) leave the house, I went out to the car, popped the hood,
and found that the snow had come in from underneath and packed itself level
with the underside of the hood... Hood came up and not one part of the
engine was visible. It took a flashlight in the mouth and a fair amount of
digging to uncover a hole large enough to find the pump belt and install
the pump.. Even the banjo fittings were packed full and had to be blown out
Good, character building stuff.. and a good reason to contemplate a garage,
or, almost as good, do it in the summer, at your leisure.
Anyhow, I've repeated the procedure since then, and have yet to have any
leaks with either of the pumps. Hopefully, Your Mileage May Be Much The
Future UNauthorized rants will include replacing the (low pressure)
hydraulic hoses and re-using the crimp type banjo fittings-or "More Fun
With The Dremel and Bench Grinder". Possibly even "Cutting the Hell out of
Your Headlights for Fun and Better Visibility"
Somebody stop me if any of this DIY stuff veers into the realm of the
Hazardous or Not Recommended, Outright or Partially...