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454 low oil pressure.

Discussion in 'Engine & Performance' started by 86Peter454, Jun 2, 2020.

  1. 86Peter454

    86Peter454 Full Access Member

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    hello.

    been a while since ive posted here mostly just been lurking around.

    well i have an issue with my truck that popped up recently. my old man changed the oil on the truck and a couple days later i noticed the oil pressure was quite low.

    the truck is an 86 with a 454 and turbo 400.

    the truck when you first start it up cold will go to about 30psi then once its warm it will idle at 0 maybe 5 psi. cruising with rpm around 2500-3500 the oil pressure is in the 15-20 psi range.

    first think i thought was maybe its the oil but he used 10w-30 like i did last time i changed the oil. then next was the oil filter he used a napa gold that i asked him to use but last time i changed the oil i used an ac delco. i thought maybe something with that i think some have a pressure release in the filter or something im not sure i just figured it was worth a shot putting an ac delco back on the same as it was before as thats all that had changed.

    so after changing the filter the oil pressure was still just as low. oil level is just fine as well.

    anyone have any thoughts? my next plan is to try a different oil pressure gauge just incase the gauge isnt working but i dont think so as it seems to still move and change with rpm.

    any thoughts or insight would be much appreciated.

    MattTruck-24.JPG
     
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  2. SirRobyn0

    SirRobyn0 Full Access Member

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    Hi there, As we all know these trucks are known to have gauging issues so that's definitely a possibility. If it was me I'd want to do a manual test of the oil pressure with a test gauge. If you don't have one harbor freight sells them for about $30. That's were I'd start and then you'd know if it truly is low engine oil of if it is a gauging issue.
     
  3. PrairieDrifter

    PrairieDrifter Full Access Member

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    X2 get a manual Oil pressure gauge and check it that way then report back.
     
  4. 80BrownK10

    80BrownK10 Full Access Member

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    I'd either test it with another external gauge or just replace the sending unit as there cheap.
     
  5. PrairieDrifter

    PrairieDrifter Full Access Member

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    Not a bad idea to change out an original sending unit. But that doesn't prove the gauge is reading correctly.
     
  6. 80BrownK10

    80BrownK10 Full Access Member

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    Your correct, that would rule out or fix a faulty sending unit.
     
  7. 86Peter454

    86Peter454 Full Access Member

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    alright i put in a temporary oil pressure gauge. its put in at the port in the front driver side of the block. i had to remove the power steering mount to get to the port though so i didnt do any driving around in the truck. the gauge is one i bought for troubleshooting transmission pressure but i suspect it will work fine for this application.

    here are 2 videos. one with truck cold and one with engine warmed up.

    based on the videos i suspect everything is fine its just the gauge is messed up but let me know your thoughts.

    engine cold


    in this one with the engine warm usually the gauge in the dash will read pretty close to 0psi though this time it didnt it read closer to 15ish psi but the other gauge read higher.


    as i said let me know your thoughts.
     
  8. 82sbshortbed

    82sbshortbed Get outta there! Supporting Member

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    My 454 rus about 45 to 50 at idle and it's hooked up to the same port as yours is. Drivers front behind ps pump.
     
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  9. illmanners

    illmanners Junior Member

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    Typically, 10 pounds per 1000 rpm is recommended oil pressure at operating temperature. On a cold fire-up, a 454 in good running condition should be producing 40 to 70 pounds according to Chevrolet (1992 GM Repair Manual.) It appears that both your oil and filter are fine, however, since you are getting different readings from the OEM installed gauge and the remote pressure gauge, I'd check both the gauge and sender as typically, they are suspect for poor grounds. Unless I'm viewing your video incorrectly, you are developing less than 5-pounds of oil pressure at operating temperature at 500 RPM? If that is indeed an accurate reading, coming from the oil pressure test gauge, plumbed directly to the engine, either that gauge is also incorrect, there is a blockage in either the engine the oil passage leading to the hose that is connected to that gauge, or the hose itself. If none of that is true, you have either cam and/or main bearing issues, neither of which would have been caused by an oil change. Please keep us posted.
     
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  10. Bextreme04

    Bextreme04 Full Access Member

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    No, the PSI reading is the outer numbers. The red numbers on the inside are BAR. So it looks like the interior gauge is reading about 10 psi lower than the exterior direct connection gauge. It looked like 40 psi cold and 20-30 psi with the engine warmed up. It should be noted that just because the engine coolant temp is reading hot, does not mean the engine oil is up to operating temp. It usually takes a good 20-30 minutes of driving for the engine oil to get up to near coolant temp. You will likely see the oil pressure come down more once the engine oil actually gets hot, but if the gauge on the dash was reading a little above 0 and the same offset scale applies, you were likely at around 10-15 PSI at idle with hot engine oil, which is within specs for an older engine.
     
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  11. 86Peter454

    86Peter454 Full Access Member

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    yea i agree with you here.

    the outer marks on the gauge would indicate 20-30psi warm.

    yea as i said i couldnt go drive it around but it sat idling in 90* heat for 15-25 minutes while i let the engine warm up. i suspect the gauge is just off a bit and with the 10psi for every 1k rpm rule of thumb i suspect im in a safe range just need to fix the gauge in the dash.
     

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