Date: Sun, 27 Nov 2011 22:27:27 -0500
Reply-To: pickle vanagon <greenvanagon@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: pickle vanagon <greenvanagon@GMAIL.COM>
Subject: Oil pressure light in 1.9l at idle
Content-Type: text/plain; charset=ISO-8859-1
On our returning-home-after-thanksgiving drive, we had some scary oil light
flicker.
Here are the details:
Engine has just a little over 100k miles on it.
I typically run Mobil 1 15w50 in it, but shortly before this drive changed
the oil to Castrol Syntec 5w50, hoping to achieve better lubrication during
cold-starts in the winter. I used a Mobil 1 filter (which I've used
occasionally before, though now it was replacing a Fram tough-guard).
Flicker definitely seemed related to oil pressure. That is: it only came
on after driving fast for a long block of time, and then letting the engine
drop to idle. After I first noticed a flicker happen once and confirming
the oil level was fine, I tried this experiment several times and could
often get some flickers out of it, although not always. Raising the engine
rpms *at all* would completely kill the flicker. I couldn't give it even a
tiny amount of gas and still have flicker, even after a long run.
Further mitigating factors:
We have an auxiliary battery setup with heavy gauge wire coupling the
batteries via a Stancor relay. The auxiliary battery is a year old or so
and so almost certainly in worse condition than the starter battery, since
that never gets drained at all. I have the batteries set up so that a
switch can be used to kill the stancor relay when driving (or force it to
be engaged when the engine is off). Anyways, with the stancor relay
disabled, I wouldn't get any oil light flicker, as the engine was idling
high enough to avoid it. The flicker was only happening after a long fast
run *and* at especially low rpms, which would only happen when both
batteries where being powered by the alternator.
Obviously I find this all pretty scary! I figure the first step is to
figure out what my oil pressure is at various operating speeds and
temperatures. So I've ordered parts to install an oil pressure gauge.
I realize there's a lower threshold (blue) .25 bar switch that VW
recommends to replace the existing .3 bar switch, which would likely
eliminate my flicker, but right now I'm just worried this is an indication
of deeper problems. I've ordered one of these switches anyways just in
case my current switch is bad, but the behavior I'm seeing rules out a
wiring issue I think, and I haven't actually heard of anyone having an old
switch that was still responding, but just at too high a pressure (if
anything I would expect them to fail in the other direction.)
I also realize the switch to castrol 5w50 may have been what made the
difference. But I'm reluctant to throw back in some 15w50, have the light
go back off, and then just call the problem solved... I mean, I shouldn't
really be that close to the edge of triggering the switch right? Or should
I be considering it likely that the 5w50 really was just too unstable in a
1.9l (which has no oil cooler) at high speeds?
I'll be grateful for any advice... wow, I hope this engine isn't giving up
on us!! I was planning on getting a lot more life out of it...
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