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No oil pressure at start up, 2001 Tahoe

Discussion in 'Engine & Drivetrain' started by Chads93GT, Dec 11, 2014.

  1. PNW VietVet

    PNW VietVet Supporting Member

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    The City of Roses.

    It's a shame.

    Hard on oil pressure and wipers.
     
  2. Tonyrodz

    Tonyrodz Resident Resident

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    Same thing happened to my lq4. Mine was also an 05. Spun a cam bearing from low to 0 oil pressure.
     
    Last edited: Apr 28, 2021
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  3. clandr1

    clandr1 Full Access Member

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    In the last month I've noticed my oil pressure at idle seems lower than desired (I'm used to seeing it around 40 PSI, but lately it's dropped down to 20 PSI after the motor is warm). At speed, it's still at or above 40 PSI, depending on throttle application.

    I've owned this truck since it was new, and the only issue I've had with oil pressure is about 3 years ago I had a very sudden and steep drop with some valve clatter. I replaced the oil pickup tube o-ring and it was back to normal operation.

    The oil has about 5k miles on it (I've used Mobil 1 High Mileage since 75k miles, and always wait until the oil change monitor hits 0% and tells me to change the oil), and the temperatures in Texas have been rising, but it still seems lower than it's ever been (even in the middle of the summer).

    Any idea what the likely culprit is here? Or am I worrying about nothing?


    oil pressure.jpg
     
  4. PNW VietVet

    PNW VietVet Supporting Member

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    If oil is full and no clattering noises, then I would suspect the sender/sensor. I was gonna say the o-ring but you have addressed that unless it is acting up again for some reason. I believe the way they said here to test for the o-ring is to overfill by 2 quarts and point nose downhill and if pressure reads higher, then the o-ring is bad.
     
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  5. Rocket Man

    Rocket Man Build It Better Supporting Member

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    I would change the oil and make sure to use a good filter like Wix or ACDelco and then keep an eye on it. If it keeps getting lower then you can start worrying. Hopefully new oil and filter will bring it back up.
     
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  6. clandr1

    clandr1 Full Access Member

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    Probably a good first step. I've been using AC Delco filters for the last 2-3 years, and before that it was a combination of Bosch, Wix, and Mobil 1 for as long as I can remember. I did take a really long trip to MO (7 hours one way) in the middle of March - perhaps that took more out of the oil than my usual around town trips and thinned it out ahead of schedule. If that doesn't fix it, I'll explore the sensor.

    Thanks everyone, I'll update the thread when I have more.
     
  7. Jimmyy

    Jimmyy Full Access Member

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    “Hard on” :hahano:
     
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  8. clandr1

    clandr1 Full Access Member

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    Just changed the oil with Mobil 1 5w-30 high mileage and an AC delco filter. No change. I grabbed a sample and will send it off to Blackstone Labs for analysis before I do anything else.
     
  9. livingez_123

    livingez_123 Full Access Member

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    Why are you waiting for the the idiot reminder to change the oil? And also why are you using 5w30 in an engine that has over 200k on it?
    Even after I refreshed my engine and checked all of the bearing clearances which were on the loose side between .0018-.0020 new they will be .0008-.0015 I run 15w40 and change it every 3-4k.
    You need to check the pressure right off the pump using the front oil galley plug behind the power steering pump. I feel anything over 200k miles is a bonus, bearings do wear out and clearances get greater and oil pressure goes down. I'm glad I decided to go with a high volume oil pump, I would have been disappointed with a stock one.
     
  10. clandr1

    clandr1 Full Access Member

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    Overlooking the condescending tone in your post, my general answer is "because that is how they designed it". Additionally, I've periodically had my oil analyzed by Blackstone and historically all wear indicators were in line and of no cause for concern. Bottom line is, everything has been working well so I've been doing what the owner's manual calls for. If this most recent sample shows an increase in bearing wear, I'll happily change to a different oil if it'll counter the degradation inside my motor.
     
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