[s-cars] Changed Pump X-Plug, No Brake Boost - Any Ideas?

[Kirby Smith]

Fred:

I think steering and braking are on separate circuits at opposite ends
of the pump.  Presumably, the high pressure end is the end where the
high pressure hose connects.

O-ring thickness sensitivity is very interesting.  (And raises a
question about design shortcuts, as if we didn't have one given that the
o-rings leak, something that shouldn't happen with a static ring.)  Not
having looked into an x-plug hole, I don't know what is in there besides
a rumored piston.  Are there any orifices near the o-ring?  Did you
change the "compression ratio"?  You get no pumps from the bomb?

kirby



Fred Munro wrote:
> 
> Hi Guys;
> 
> The hydraulic pump X-plug on my '94 S4 was leaking, so I changed the o-ring.
> Prior to removing the plug I bled off the pressure from the bomb - it took
> 50 pumps. I pulled the plug and replaced the o-ring with a slightly thicker
> one I had on hand, so the plug doesn't seat to exactly the same depth. It
> doesn't leak, but the bomb won't pressurize. I ran the car for 5 minutes or
> so - no brake boost at all. The power steering works fine. Any ideas? What
> circuit is the piston under the plug on - brake or steering?
> 
> TIA
> 
> Fred Munro
> '94 S4
> 
> -----Original Message-----
> From: s-car-list-bounces at audifans.com
> [mailto:s-car-list-bounces at audifans.com]On Behalf Of Dave Forgie
> Sent: January 18, 2004 12:55 PM
> To: s-cars
> Subject: [s-cars] Fumoto Valve and Michelin Man Issues
> 
> S-gruppees:  I changed my oil yesterday. While doing so I noticed one
> on-going problem and one "new" one:
> 
> 1. There was oil on the intercooler inlet - obviously from a leak around
> the Michelin Man outlet end.  I had this problem before - bad OE gear
> clamp.  I thought that I had cured it with a new gear clamp.  Apparently
> not.  I took the hose off, cleaned out some of the oil puddled in the
> big accordian pleats, cleaned the outlet end of the hose and the inlet
> end of the IC and then put it back together.  Tightened things up real
> good (I think).  Should I be looking at a better clamp, like the ones
> people have used with the SAMCOs?
> 
> 2.  I have been running a Fumoto drain valve for years. I thought
> everything was fine but on closer inspection, i.e. during the time I was
> playing with the Michelin Man, I noticed that the Fumoto was weeping out
> the end (not at the ball) where there is a circular plate and an the
> C-clip.  I don't remember this before.  I didn't do anything different
> this time.  Has it always been doing this and I didn't notice before
> because the belly pan got put on too quickly?  (The motor doesn't use
> any oil in 5000 km). The belly pan has oil and dirt on it but I have
> never cleaned it. (Going out right now to the pressure car wash to clean
> it).  Any BTDT's or??
> 
> TIA
> 
> Dave F.
> 
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