No oil pressure at start up, 2001 Tahoe

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

  1. Chads93GT

    Chads93GT Full Access Member

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    For the past 45k miles my truck has had its oil pressure drop to zero, within 20-30 seconds after start up. It was not the result of a bad sensor as I tried replacing that first, besides, the loud ticking that would almost always follow was a pretty good sign of the problem. If I immediately took off driving, the pressure would stay up, but I had to keep the rpm's up. Once the vehicle warmed up everything functioned normally until the engine got cool again.

    I bought an oil pump with the intention of changing it out but a friend told me to just change out the oil sump O-ring instead as usually that is the issue with no oil pressure in a 5.3.

    On a 2x4 Tahoe it is very straight forward to drop the oil pan to access the sump and access the O ring. You have to remove the cross brace under the oil pan which is 4 bolts. You also need to remove the two oil pan/bell housing cover bolts (they hold a small plastic shield in place that keeps road grime out the bell housing. You also need to remove two bolts that hold the wiring harness in place. A simple electrical connector on the low oil sensor then you can drop the pan by removing all of the pan bolts.

    Once the pan is down there are two nuts that hold the oil sump to the main bearing caps, as well as the small bolt that actually bolts the sump tube to the bottom of the oil pump. I removed the O ring and it was flattened out like a wedding ring, but not cracked or deteriorated. It was very loose when pulling out the tube as well. I put the new O ring on, which was $2 and shaped more like a fat doughnut. It was harder to press the oil sump tube back into place but it was fairly easy.

    Scotch bright pad was used to clean the grime from the block where the oil pan gasket seats. I had a bad oil leak forever and the pan gasket was the culprit as it had long since flattened out as well. Once the oil pan was cleaned up and both surfaces cleaned for a new gasket I had the truck back together and running in less than 3 hours.

    High oil pressure once again. With 526k miles this is the most extensive "tearing" into the drive train I have had to do, other than a 2-3 shift solenoid going back in the transmission a while back.

    Hopefully this thread will help anyone with similar oil pressure issues who thinks they need a new engine, when in reality you can fix it for $60 in parts and an oil change.

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    RET423 and Lvmywife01 like this.
  2. PNWstorage

    PNWstorage Full Access Member

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    Thanks for the info and the pics.
     
  3. Chads93GT

    Chads93GT Full Access Member

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    I am not sure why the one of the engine's crank case/sump area is upside down but whatever. The 2nd photo shows you where the oil pickup tube bolts to the bottom of the oil pump. Pretty straight forward fix.
     
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  4. 07Burb

    07Burb GM fan for life Staff Member Supporting Member

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    Seriously??? 526k miles?? :eek: Holy Moly!!!!!
     
  5. PNWstorage

    PNWstorage Full Access Member

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    Holy Moly is right. I just noticed that after you posted. May be a record.
     
  6. redemn93

    redemn93 Full Access Member

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    are you saying thats a factory trans with only a solenoid replaced?
     
  7. Chads93GT

    Chads93GT Full Access Member

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    Factory trans, yes. It was 450k miles or so when the solenoid went out. was the only time I had ever took the pan off as well. Figured it was time for a filter change at that time ;).

    Really all this truck has had is 5 hubs, 5 ujoints, 2 fuel pumps, shift solenoid, oil pump oring, 3 tensioners, thermostat, knock sensors, and.............uhh............. head light switch/blinker switch and the throttle position sensor in the gas pedal. Still runs like new to tell the truth. Ive had it since 100k miles. 2nd owner. was a corporate lease vehicle before that.

    and a radiator
     
    Last edited: Dec 11, 2014
    RED TAHOE LS likes this.
  8. PNWstorage

    PNWstorage Full Access Member

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    Lucky guy. Go get a lottery ticket.
     
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  9. 07Burb

    07Burb GM fan for life Staff Member Supporting Member

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    A vehicle with that kind miles you just hang on to and keep on driving her and see how far she can go with good routine maintenance. Kind of a fun thought actually :) Keep it up, man!
     
  10. PNWstorage

    PNWstorage Full Access Member

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    Yea we need constant updates about this rig. You need to start a special thread for just that.
     
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