Oil pressure dropped! - Team Camaro Tech
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post #1 of 10 (permalink) Old Sep 4th, 03, 04:25 PM Thread Starter
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This is on my '88 C1500 p'cup. Drove to town to pick up a couple [img]graemlins/beers.gif[/img] and when I pulled into my driveway and was about to turn off the engine, I notice the "check gauges" light was on, looked at the oil pressure and it was near zero, killed the engine, checked oil - good - cranked engine - rev'd a little - wouldn't get over 30 psi - idle - back to almost zero. I am going to change the sending unit and see if that is what it is. Has been running a good 30 at idle and up around 60 cruising so I don't think it is the pump. It is an '88 but only has 85K on 'er. Any thoughts.
Thanks,
Guy
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post #2 of 10 (permalink) Old Sep 4th, 03, 06:25 PM
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Electric sending units are always suspect when anything goes wrong.
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post #3 of 10 (permalink) Old Sep 6th, 03, 02:42 PM
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I'm pretty sure there is a separate sender for guage and idiot light. the light is just a switch, the guage sender is a variable resistor.
Usually the guage sender is near the distributor.

If the pressure got too low, I think the electric fuel pump relay will stop the fuel pump.

If you are lucky, the pickup fell off your oil pump.
David

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post #4 of 10 (permalink) Old Sep 6th, 03, 03:30 PM
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Guy,
My 85 Blazer did the same thing and it was the sender. About scared me to death when I happened to look at the gauge and it said "0" Try tapping on the sender with a long screwdriver and see if it changes, thats what I did. By the way Dave, I "think" that the check gauges light is actually triggered through the ecm by way of the gauge sender on the later trucks.
Hope its the sender !

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post #5 of 10 (permalink) Old Sep 6th, 03, 05:15 PM
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Sounds like one of the first things you should do is get a schematic and see how many senders are on the vehicle. It is very likely that there are two separate ones. One for the guage and one for the ECM. It is likely that the ECM is what is illuminating the light, but that isn't a conclusive diagnosis without knowing exactly how many sensors are on the engine.

-dnult

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post #6 of 10 (permalink) Old Sep 7th, 03, 08:42 AM Thread Starter
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I changed the sending unit located near the distributor with no change, but quess what, there are two sending units with the other being located off the boss near the oil filter, "hidden" inside a cone shaped heat shield. This is the one that affects the gauge. I will change it this week and let you know what happens. I really don't think my oil pressure dropped overnight.
Thanks,
Guy
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post #7 of 10 (permalink) Old Sep 7th, 03, 12:57 PM
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Sounds like you've isolated a real oil pressure problem then. [img]graemlins/sad.gif[/img]

-dnult

Dave
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post #8 of 10 (permalink) Old Sep 11th, 03, 06:08 PM Thread Starter
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BINGO, bad sending unit, oil pressure back to normal, now to change those leaky valve stem seals.
Later,
Guy
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post #9 of 10 (permalink) Old Sep 12th, 03, 02:06 PM
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That's great news, glad to hear it. I was convinced that after replacing the other sender with the same problem. Did the first sender fix the "check gauges" problem or the second?

-dnult

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post #10 of 10 (permalink) Old Sep 13th, 03, 11:03 AM Thread Starter
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Dnult,
I couldn't tell you which one fixed the problem because I never let the engine get warm enough for oil to heat up and the pressure to drop low enough for the "check gauges" light to come on. I can tell you this, when I replaced the sending unit located at the back of the engine near the dist. it had no affect on the gauge. I even disconnected it and cranked 'er up and it had zero affect on the gauge reading and the light didn't come on. I would have to say it must be the one near the oil filter that would affect the "check gauge" light.
Guy
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