sudden drop in oil pressure -- causes the check guages light to come on.

matt guesto

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Jun 17, 2001, 10:05:55 AM6/17/01

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This started happening last week.

My 1994 S10 with the 4.3 Vortec engine has started dropping the oil pressure
at stop signs. When the pressure drops into the "red" zone on the guage the
check gauges light comes on. The engine has 141,000 on it and is driven
daily without trouble.

The Oil that was in the engine was of good quality 10-30 and a Fram filter.
The current weather temperature was in the upper 80's here in Allentown, Pa.
So
I changed it to 20 - 50 hoping this would be the cure.

I am still getting this drop in pressure and check guage light. I tried
looking in some Chilton (sorry) manuals but found no reference to an oil
pressure sending unit that might be acting up. This book has nothing that I
could use to help solve this.

Has anyone had this experience? And what suggestions would you have that I
can try. I hate the idea of having the engine pulled to replace the oil pump
if it would be some sensor malfunction.

thanks for the time.

Matt Guesto

This was also posted in Alt.trucks.chevy

flytngneer

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Jun 17, 2001, 5:10:13 PM6/17/01

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Remove the oil pressure sending unit and install a dial type "direct
reading" pressure gauge and see what you get with the engine rpm's up and at
idle. It will give you the real info you need to know to continue further
with fixing your problem. Maybe pull the oil filter and see if it is full
of oil. How is the coolant temp. acting?

Hope it helps.

Thomas Murden

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Jun 17, 2001, 10:31:33 PM6/17/01

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If you get no valve train noise when the pressure drops it's a safe bet that
the oil pressure switch is bad.
Tom Murden

"matt guesto" <mgu...@po-box.esu.edu> wrote in message
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Kentor

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Jun 18, 2001, 9:15:25 AM6/18/01

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I had this exact problem with my 5.0L engine with 167,000km on it. I
replaced it with a 5.7L. We checked the pressure with a mechanical
gauge and it agreed with the dash gauge. We disassembled the 5.0L just
to see what was wrong. The oil pump was in perfect condition, wear was
within spec. The main and rod bearings showed a little wear but
definitely not wore out. We didn't check the cam bearings. About the
only thing we can think of is all the bearings are wore just enough to
cause the pressure to drop at idle. We did find some crud on the oil
pump pickup screen but we suspect it came from the bottom of the oil
pan when we flipped the engine on the stand, but maybe not. BTW, there
was not a sound from the valves at all.

There's not much you can do, either drive it with heavy oil or yank
the oil pan off and replace the main/rod bearings and check/replace
the oil pump.

Ken R.

Leonard Bauman

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Jun 18, 2001, 5:57:53 PM6/18/01

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Try installing a new oil pressure sending unit. I don't know where
it's at on your truck but it will tell you in your manual. I had a
similar problem in my 1989 GMC, the pressure never went down. It went up
to 60psi as soon as you started it and the sending unit was the problem.

GOOD LUCK!!

Drew Blouch

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Jun 19, 2001, 7:22:01 PM6/19/01

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sounds to me like your oil pressure sending unit took a powder. Same thing
just happened to my chevy truck.

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Horace, Tina, & Brandon

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Jun 21, 2001, 7:21:01 PM6/21/01

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My wife had same problem with her 92 s-10 blazer. The oil was low. Hope this
was the first thing you checked.

If people concentrated on the really important things in life, there'd be a
shortage of fishing poles.
Doug Larson

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