Oil pressure help.

Discussion in 'General Automotive Tech' started by chevy5seven, Dec 20, 2012.

  1. chevy5seven

    chevy5seven New Member

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    I have a 1991 Caprice wagon with the 305 TBI. Couple of days ago the oil light would stay on a little longer than it has been. Yesterday stayed on a little longer say a minute. Today stayed on for about 5 miles. When rpms would go down it would flicker then go out, when accelerated it came back on. After about 5 miles it went off and stayed off. No unusual noises, no ratteling, not skipping, ran just as good as it always has. I am thinking the sending unit? Need some opinions! Thanks guys.
     
  2. Eagle Freek

    Eagle Freek Well-Known Member

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    Dumb question, have you checked the oil level? I would inspect the wire going to the unit and make sure it's not shorting out and then replace the oil sending unit just to make sure. I would either install a mechanical gauge or temporary gauge to verify the actual oil pressure.
     
  3. chevy5seven

    chevy5seven New Member

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    LOL.......yes checked oil. :rofl:
     
  4. moparpaw

    moparpaw New Member

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    oil pressure

    change the sending unit....if you had any internal problem the engine would make noise if you drove for 5 miles......jmho.Phil
     
  5. dodgeguy

    dodgeguy Well-Known Member

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    If you are losing oil pressure for whatever reason, the light will usually go out when you accelerate and come on at idle. Sounds like maybe a sending unit. Don't rule out a clogged oil pump pickup.
     
  6. unkldave

    unkldave Cockroach Dave

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    could be something you should take a look into. the factory oil sending units don't light unless the pressure gets below 10 pounds of pressure. I would like to think it is the sending unit but I would check the oil pressure at the sending port. I would also get rid of the factory unit and put in some aftermarket gauges. that way you can have both the factory and some true pressure indicators of how your engine is running. If nothing else, you'll have some cool looking gauges that work instead of the dummy lights.
     
  7. 65 2dr

    65 2dr Fix 'em all -

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    I'd be chancing the oil to 'high-mileage' oil, and cutting the old oil filter for inspection.
     
  8. moparpaw

    moparpaw New Member

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    57 nice looking wagon....................if you had no oil pressure you would have been looking for a 350, already:cry:
     
  9. chevy5seven

    chevy5seven New Member

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    Guys thanks for the input. I changed oil and filter Saturday. I believe the cuprit was a clogged oil filter. Took the old on off drained it and I bet it weighed 2-3 pounds!! Bought a new sending unit, but didn't have right socket to change, 1" deep well, had a 1" shallow. Nearest place to purchase anything is 12 - 15 miles sooo, decided to try just changing filter and oil. And no more oil light, everything is good again!!
    Again thanks to you all. And moparpaw I am looking at a 350!!!:)
     
  10. moparpaw

    moparpaw New Member

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    Well at lease you got it.................but I don't understand how it got so plugged...do you change you oil regularly...............I sure like that stripping on the hood
     
  11. Eagle Freek

    Eagle Freek Well-Known Member

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    What brand filter?
     
  12. 200OZ

    200OZ Well-Known Member

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    Better quality filters will hold oil in them making them heavier when you remove them, it might not be clogged. On the other hand the early 305s were very suseptable to clogged oil drain holes in the cylinder heads. Frequent oil changes from the begining was the only answer. You may have some of those deposits cloging up your filter. Give that a looksy.

    Mike
     
  13. cadipacer

    cadipacer Well-Known Member

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    Yes,, tell us what brand filter came off car ( I think I know):49:
     
  14. chevy5seven

    chevy5seven New Member

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    No markings on old filter, in a moment of weakness I had the oil changed the last time. I didn't do it :coco:. Probably some fleet deal filter. But it was at a muffler shop and while it was up me and the owner looked at exhaust and he gave me a price on duals from manifold back with flowmasters and tips. And remove cat. $350-375 Ouch! Well, lesson learned!:)
     
  15. MikeT1961

    MikeT1961 Well-Known Member

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    When my brother looked into getting a dual exhaust on his 86 Parisienne, with the 305, he was warned against doing it by a muffler/hot rod shop. The owner told him that the factory Chev small blocks (NOT including LS-1) need the back pressure. The valve springs are a bit weak. A dual will help gas mileage and performance for a short while, but before too many miles are on, head problems develop and an engine rebuild is in the cards. He stuck with a single exhaust, and got almost 400,000 miles out of the engine, and it was still not burning oil.
     

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