5k Pentosin leak - long & detailed

[Fred Munro]

Iain;

This may be the "volcano syndrome" wherein the Pentosin spews from the
reservoir cap. I've never seen a post detailing the actual cause, other than
it's a problem with the hydraulic pump. You might be able to find some info
in the archives by searching under "volcano".

Fred Munro
'94 S4

----- Original Message -----
From: "Iain Mannix" <mannix at rmsolo.org>
To: <quattro at audifans.com>
Sent: Saturday, November 24, 2001 11:58 AM
Subject: 5k Pentosin leak - long & detailed


> OK, so I posted yesterday saying that my new 86 5kcsq had a
> flashing brake light for no reason.
>
> I lied.
>
> It is _leaking_.  From the reservoir.  From the beginning -
>
> Bought an 86 5kcsq from a friend/mechanic in Boulder to replace
> my not-so-gracefully aging 87 5kcsqa.  The 87 needs valve seals,
> possibly a valve job, a starter(soon), the starting problem
> fixed(cranks FOREVER), rear clunks galore, clutch is
> questionable, a paintjob, etc etc etc - maybe it is time for a
> new car.  Found the 86 - needs interior bits(87 has those), a
> headlight(87 has that), stereo, etc.  The 86 is a strong running
> car, has a bit of a grind in 2nd or 3rd (but never both at the
> same time, that's an interesting one, but the 87 has a tranny),
> basically, all of the good stuff on the 87 could be put to use on
> the 86, and the bad stuff on the 87 is largely good on the 86.
> Match made in Germany?  Something like that.
>
> I asked about the basics WRT the 86 - timing belt, hoses,
> bushings, etc.  All good.  When I picked the car up Wednesday
> night, it had no brake light issues.  Drove it 50ish miles,
> parked it, put a throttle cable on, changed the tranny fluid to
> MT90, drove it again - brake light.  Initially, nothing seemed
> wrong - but through Thursday and Friday, it became apparant that
> there IS a leak, contrary to my original posting.
>
> It appears to be leaking from the cap.  I found that the car had
> no plunger/level sender when I topped off the fluid - put the
> plunger/spring/washer in from the 87, no change.  Tightened the
> hose clamp from the brake master to the reservoir - thought that
> was it.  No.  Tightened the bigger hose that comes from the pump
> to the bottom of the reservoir(bottom-side, not the one directly
> off the bottom that appears to go to the bomb).  That clamp was
> loose, but still no change.  Cleaned the top of the reservoir
> thoroughly, drove it 30ish miles this morning.  Went from the
> full line to "fill me" in 15, same on the way back.
>
> It appears to be leaking from the cap itself, based on the mist
> of Pentosin on the firewall, the wetness on top of the reservoir.
>
> The cap has a good rubber seal in it.  Currently, the spring that
> normally goes between the washer and cap is out - I theorized
> that the spring is pushing against the cap, causing a gap - the
> car did not leak a bit before I picked it up, and it had no
> spring/washer/plunger.  Ok, that's not it.  It seems as though
> something is pressurizing the reservoir - I don't KNOW this, but
> I was not under the impression that the reservoir should be
> pressurized.  Correct?
>
> Questions:
>
> Is the reservoir supposed to be under pressure?
>
> If not, what could do that?
>
> I've never heard of a leaking reservoir - it _looks_ ok, but
> maybe there's a crack at the base of the threads facing the
> firewall - is this unheard of?
>
> Any thoughts?
>
> Where does the rack normally leak from?  I do not see any leaks
> in the rack; it appears to be coming strictly from the reservoir.
>
>
> Don't know.  Not what I wanted to deal with on a new-to-me car,
> but oh well.  I might swap reservoirs between cars tomorrow, see
> if that fixes things.  All I can think of - but if my suspicion
> that the reservoir is NOT supposed to be under pressure, that
> won't fix anything.
>
> Thoughts?  Some sort of check valve in the PS/booster system that
> is allowing the reservoir to be pressurized?
>
> Thanks - I've been lucky enough to have avoided Pentosin leaks
> that are not plainly obvious - had a couple of hoses go, they're
> easy to figure out.  This one is weird to me; hopefully, this is
> not weird and the answer is "replace the reservoir."  Is that a
> possibility?  Unfortunately, I can't replace it today and find
> out - wanted to get insight from the masses first; anyone ever
> have a reservoir fail like this?  Is this weird?
>
>
> Thanks!
>
>
> Iain Mannix
>
>
>