RE: IML: '82 oil pressure issues

["Dick Benjamin" <dickb@xxxxxxxxx>]

My guess is that your idle speed is set too low, and your oil pressure is
right at the threshold of triggering the oil pressure warning sender (which
is probably set to go on at about 7 PSI). I am amazed that putting thicker
oil in it made no difference - I thought you previously had 10W30 in it,
there should have been a quick and noticeable improvement in oil pressure
when you switched to 20W50.  I can't explain it, unless your slow idle
(causing rough idling) is shaking things so bad that the oil pressure
sending unit wire is getting tapped on something that is grounded - inspect
that wire and make sure it can't touch anything.  Anything that grounds that
wire will bring on the warning light.

If you can find nothing like that, and your idle speed is pretty close to
700-750 RPM, I think you need to beg, borrow or steal a real oil pressure
test gauge, and see what you've got there, hot engine, at idle.  We'd like
to hear you've got 30 PSI or better, but even 15 is good enough to keep
driving it for a while.

If you have a tachometer, check your idle speed. If the engine is tired, it
probably needs to idle at 700 RPM in drive, AC on, to avoid a shaky idle.

None of this sounds like impending doom to me - cars run for years and years
with tired engines - usually something else will cause you to rebuild it -
like a burnt valve causing a persistent miss, long before a bearing spins.
Just listen to it - if you don't hear any loud knocking when you first start
it (first few turns on the crank), your main bearings are not about to let
go, and if you don't hear any rapping on the overrun (high rpm, lift off the
gas) your rod bearings are not about to let a rod poke through the block. On
the other hand, if you do hear such noises, pay attention - the tow truck is
circling you!

Dick Benjamin

-----Original Message-----
From: mailing-list-owner@xxxxxxxxxxxxxxxx
[mailto:mailing-list-owner@xxxxxxxxxxxxxxxx] On Behalf Of Nat Hall
Sent: Thursday, June 15, 2006 8:20 PM
To: mailing-list@xxxxxxxxxxxxxxxx
Subject: RE: IML: '82 oil pressure issues

This is going back a month, but...

>
>Third: Your low oil pressure warning is a sign that either your engine is
>getting a bit tired, or the engine has the wrong oil in it.  If you don't
>know what oil is in it, I'd recommend changing the oil and oil filter, and
>using either 15W40 or 20W50 oil in it.  This will probably make the low oil
>pressure indication go away for a while, but sometime in the next 100,000
>miles, you may be in for an engine rebuild.   I had a similar car with
>almost 300K on it, and I had a similar symptom - so they do wear out, but
it
>takes a long time.

The above excerpt was from Dick Benjamin in response to a message I
originally posted. Basically, the gist of it is my '82 coupe flickers the
low oil pressure light (*only* at idle) after a drive on the freeway of 20
minutes or longer.  I can drive around town all day long without a freeway
trip and this will not happen.  Additionally, it will only happen sometimes
and is not reproducible 100% of the time. The low oil flicker is always
accompanied by a rougher-than-normal idle. Putting the transmission in
neutral or park will make the low oil flicker go away. Even when this
happens after a romp on the freeway, driving around town for a bit at lower
speeds will return the idle to normal and make the low oil warning go away
even without the use of neutral. The car is carbureted and not EFI, but I
don't see how that has any bearing on this.

Following Dick's response above, I *did* change the oil and filter and used
20W-50 instead.  This didn't affect the low oil warnings at all.

The oil level stays right where it should be and the oil pressure sender is
not at fault-- it was replaced within the last 10,000 miles. The engine is
not making any abnormal noises.

To be honest, I have been ignoring these "low oil" warnings and I just idle
in neutral at stop lights after freeway driving until the problem goes away
on it's own.  However, recently I've been reading online some pretty grim
things about similar issues.  The impression I get is that my engine could
seize and die at any moment.  Is this something I really need to be afraid
of at this point? Since the problem only occurs occasionally and under
certain circumstances I've been assuming I've still got plenty of time
left. Won't I start hearing horrible valve clatter and notice other
symptoms before anything terrible happens?


-------------------
Nat Hall
1982 Imperial Coupe
1987 Chrysler New Yorker
http://newyorker.digital-forever.com
-------------------




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