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Oil pressure really low and high after changing sending unit

Discussion in '1st Gen Tundras (2000-2006)' started by riser56AK907, Jun 13, 2020.

  1. Jun 13, 2020 at 11:46 PM
    #1
    riser56AK907

    riser56AK907 [OP] New Member

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    So I bought a used Tundra about a month ago, and the oil pressure would go very low when I was idling at a stop light. Looked it up and found out that the set oil pressure at idle is 4-5 psi. I still thought it the gauge was reading pretty low, so I replaced the oil pressure sending unit. After I did that, my oil pressure gauge shot all the way up and wouldn’t go back down. So I went back to oreilys and returned that sending unit for another one. This time after the install, my gauge was reading negative pressure and won’t rise when giving it throttle. I also replaced the oil filter so I know that’s not clogged. Anyone have any ideas of what the F*** is going on here?
     
  2. Jun 14, 2020 at 12:38 AM
    #2
    empty_lord

    empty_lord They see me rollin'

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    sounds like its faulty sending units honestly. if you still have the original i'd reinstall it and see if it works again
     
  3. Jun 14, 2020 at 3:48 AM
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    rodm1

    rodm1 New Member

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    Last edited: Jun 14, 2020
  4. Jun 14, 2020 at 6:46 AM
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    Professional Hand Model

    Professional Hand Model A.K.A ‘Golden Hands’

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    This is exactly what I would do.

    For anyone reading this and is new to our trucks, then realize low oil pressure reading in NORMAL at idle. This freaks people out. Its NORMAL.

    A couple of observations:

    1) Never heard of our 4.7 engines dying from oil pressure issues.

    2) Our 32 OHV engines are built to run with the low idle oil pressure.

    3) Oil pressure sending units (aftermarket) seem to not work on our trucks.

    4) Never heard of anyones Oil Sending Unit ever failing. Not saying it can’t happen.
     
    robabeatle and bmf4069 like this.
  5. Jun 14, 2020 at 6:48 AM
    #5
    Professional Hand Model

    Professional Hand Model A.K.A ‘Golden Hands’

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  6. Jun 14, 2020 at 12:15 PM
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    riser56AK907

    riser56AK907 [OP] New Member

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    okay, but my stock gauge worked fine until I put the replacement sending unit. I’m gonna put the original sender back in and see if that changes anything.
     
  7. Jun 14, 2020 at 12:19 PM
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    riser56AK907

    riser56AK907 [OP] New Member

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    1. Have you ever heard of replacement oil sending units causing a dash gauge to do that?

    2. I don’t know if my original was failing. I only replaced because it would read like zero or 1 psi (I’m guessing those numbers) when I was stopped. Like the needle would lay flat with the low line on the gauge, but then go back to normal levels once oh gave it gas
     
  8. Jun 14, 2020 at 12:30 PM
    #8
    Professional Hand Model

    Professional Hand Model A.K.A ‘Golden Hands’

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    Post up a pic of your idle pressure reading on the guage.
     
  9. Jun 14, 2020 at 12:34 PM
    #9
    riser56AK907

    riser56AK907 [OP] New Member

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    Take a picture of it with the original sending unit or the new one? And quick question.. do the 03’s come with a low oil pressure light? Mine doesn’t come on when I turn the key
     
  10. Jun 14, 2020 at 12:59 PM
    #10
    riser56AK907

    riser56AK907 [OP] New Member

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    2544E84C-727B-4E5A-855D-8D15E0B9FC2B.jpg 50A6A54E-2464-4348-B768-AB7EF5FA6E1E.jpg
    here a couple pics. 1st one shows my gauges before I start it up. Notice there’s no low oil pressure light. And the second is it running after I started it. Both the aftermarket and original sender displayed the same readings on the gauge. I’m lost now. This was done on a cold start because I don’t want it running too long.
     
  11. Jun 14, 2020 at 1:46 PM
    #11
    Professional Hand Model

    Professional Hand Model A.K.A ‘Golden Hands’

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    I’m not in a place to check my truck at cold start up at 1100 rpm.

    I believe my gauge reads where yours is reading at warmed idle in DRIVE in a stopped position with the RPM at 525-50 range.

    Why is your check engine light on?
     
  12. Jun 14, 2020 at 1:59 PM
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    riser56AK907

    riser56AK907 [OP] New Member

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    Usually with a cold start on this truck, the oil pressure will read at the halfway point and once it’s warmed up it’ll idle at about quarter way and lower.

    the check engine light is because both my cats are bad. It’s was on before I changed the sending unit
     
  13. Jun 14, 2020 at 2:00 PM
    #13
    riser56AK907

    riser56AK907 [OP] New Member

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    And do you have a low oil pressure light on your truck? I don’t know if mines burnt out or it just doesn’t have one
     
  14. Jun 14, 2020 at 2:06 PM
    #14
    Professional Hand Model

    Professional Hand Model A.K.A ‘Golden Hands’

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    Sounds like normal oil pressure readings to me.

    How many miles on the truck? Your o2 Sensors (4 total) might be bad and maybe not your Cats. Our o2 Sensors tend to fail early (especially the forward 2) in front of the Cats. Densos cost about $45 each. The rears are easy swaps. The fronts require Gorilla Arm Technique.
     
  15. Jun 14, 2020 at 2:08 PM
    #15
    Professional Hand Model

    Professional Hand Model A.K.A ‘Golden Hands’

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    I have never seen mine come on or even know if there is one. Sounds like you have normal pressure based on my experience of driving my truck for 18 years. I believe your gauge is the only monitor.
     
  16. Jun 14, 2020 at 4:21 PM
    #16
    riser56AK907

    riser56AK907 [OP] New Member

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    yeah I don’t think the SR5’s have one. When I went to buy the new sending unit, they asked if I had the dummy light or an actual gauge. But I was just wondering
     
  17. Jun 14, 2020 at 4:22 PM
    #17
    riser56AK907

    riser56AK907 [OP] New Member

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    No my oil pressure gauge used to rise to the halfway point and above when I accelerated. Now it’s stuck at the quarter mark when I cold start it. And drops when it warms up. Just gonna bring it in. I don’t like driving around with funky oil pressure readings. Too risky.

    My truck has about 185,000 miles on it. But I check the CEL with a code reader and it only said my cats were bad. I already replaced the bad o2 sensor a couple weeks ago.
     
  18. Jun 16, 2020 at 10:23 AM
    #18
    Professional Hand Model

    Professional Hand Model A.K.A ‘Golden Hands’

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    Snapped a pic yesterday and posted it on another members thread about oil pressure. My truck is in ‘D’ with foot on brake and the E-Brake engaged in a parked position.

    upload_2020-6-16_13-22-56.jpg
     
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  19. Jun 16, 2020 at 11:13 AM
    #19
    YardBird

    YardBird Native San Diegan

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    LOVE the blue tint on the illumination ! Thanks for posting ~ my oil pressure gauge hovers just above the L as well . . . :)
     
  20. Jun 16, 2020 at 11:22 AM
    #20
    Professional Hand Model

    Professional Hand Model A.K.A ‘Golden Hands’

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    Thanks. Wanted something different. Gives good contrast during daylight hours. I prefer just the white bulbs for straight night driving. I pulled the OEM green rubbers off and drove that way with the whites for a little while before the Blue Switch Over. The whites show off alot of the Red/Orange on the panel. The Blue cancels those out.
     
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  21. Jun 19, 2020 at 12:31 AM
    #21
    bassman417

    bassman417 "Tundra Time". My favorite time of day...

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    when i bought my second toyota truck ,a '90, first was an '85, I noticed this on the drive home from the dealer. the oil pressure was falling to what i thought was dangerously low. I turned around and drove back to the dealership. I was told that this was normal operating range for idle. something new i guess since i never noticed this on my '85. Just got my '04 tundra and it does the same. RELAX, this is nothing to panic about.
     

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