Thanks
for the reply. It sounds like you know more about the situation than me, but why
wouldn't the buzzer go off with no oil pressure? I know the light should go on,
just like it does any time the ignition is on but the engine isn't running (such
as before you start the car). I guess I never gave the buzzer much thought,
though I did notice that sometimes the light would flash without the buzzer.
When *should* the buzzer go off?
With
regards to the "weak link", it does seem that these oil pressure switches are a
common point of failure in old 16v's, but I haven't heard anyone speak of
*repeated* failures before. I never had any additional problems with my '87
until I sold the car, which was only about 4 months afterward, admittedly. My
'88 has never had any such problems in the 2.5 years I've owned it, though this
summer I added an Audi 3-gauge panel which necessitated swapping one of the
stock switches (high pressure?) with the Audi dual-pronged unit. The engine has
150k+ on it, 25k+ of which is mine. If the PO had any problems, she didn't
include the documentation (most of which I seem to have).
Neal
Sorry for the confusion: DOPS == Dynamic Oil
Pressure (Warning) System. It uses a 0.3 Bar and 1.8 Bar sender to monitor oil
pressure under different performance modes, hand off from low to high oil
pressure is supposed to take place at ~2000 rpm. I asked about this because I
don't think I ever had the engine over 2000 rpm this morning and was curious
what would have triggered the buzzer as I shut the empty motor
off.
I know these switches are known weak links for
oil leaks, but they were both replaced for new when I rebuilt her last year. I
hope they don't fail at that high a frequency, that would seem a perpetual
warranty nightmare and recall-able issue if pursued through NHSTA.
I was not able to pinpoint the source of the leak
when I first encountered it last week, but I guessed at the oil cooler o-ring
because I believe in all my excitement to put the car back on the road last
year, I forgot to replace that with new as part of the rebuild. Seemed a
reasonable guess, based on where the oil dripped (center of oilpan and lower
timing belt cover). After this mornings outpouring, I believe that is the only
likely candidate to cause such a fast evacuation of the oil pan - it is right
after the oil pump so pressure is very high.
Cheers,
Christian
----- Original Message -----
Sent: Sunday, December 03, 2000 12:52
PM
Subject: RE: TECH: 16V Oil cooler
Perhaps I'm ignorant about what you're asking (I'm
not sure what a DOPS circuit is), but I think the two senders on top of your
oil filter flange are both involved in the warning circuit. One's a
low-pressure sender, and the other is a high-pressure sender. I don't know
the details, but the circuit seems to switch to the high-pressure sender
when the low-pressure one goes out of range. If one sender is bad or sticky,
the light/buzzer may only come for brief periods of specific engine loads
while the engine is "between senders". My '87 had this problem, and when I
replaced them both, it went away. YMMV, of course. If you're lucky, your
Perpetual Oil Change system is entirely due to the
o-ring...
I
can also relate to the oil spillage issue. After she did the
first oil change on our brand new Subaru, my girlfriend didn't notice
that the gasket from the old filter got stuck on the flange (to her credit,
I probably wouldn't have noticed either...). We drove for about three days
before the double-gasket suddenly blew out one morning after we backed out
of the driveway. We got about a mile down the road before the
oil hit the exhaust manifold and started smoking (flat-four: the exhaust
hangs off the bottom of the engine). It's been over a year, and the huge
streak on the road in front of our house is finally almost gone! You could
follow it very clearly down the street, out the neighborhood, down the
road...getting narrower as it ran out of oil. It took numerous attempts with
Simple Green to get the undercarriage of the car clean. Luckily, there seems
to be no apparent damage to the engine.
Neal
After running Windy (my Scirocco) with the
Perpetual Oil Changeâ system enabled for the last week or so while my spoiled ass
waited for warmer weather, the oil cooler o-ring finally decided it wasn't
happy being cold and disintegrated entirely when I started the car this
morning.
Pretty amazing how much oil came out in such a short period of
time - I started the car and drove maybe 20 feet when the oil light
started flashing (no buzzer). I looked in the mirror to check traffic
behind me and noticed a nice thick stripe following me, turned the car off
just as the buzzer came on too. About 3.95 quarts in 20 feet make a pretty
ugly adornment for pavement. Also makes it pretty easy to pinpoint the
offending vehicle :(
At any rate, I don't think I hurt the engine as I got it shut
down pretty quickly. Now I just have to drive the pickem'up until I can't
stand it or we catch a warm spell since the Cabby is disassembled in the
garage...
When I do go to tackle this, what size is the
nut under the oil filter that holds the oil cooler in place? IIRC, it is
pretty large and I don't think I have an open-end bigger than 24mm. I'd
rather have the right tools before I get started, so thanks for your
help.
Also, which sender controls the blinking
light and which triggers the buzzer, or are they both handled through the
DOPS circuit?
Thanks again.
Cheers,
Christian
87 16V
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