1. Registration trouble? Please use the "Contact Us" link at the bottom right corner of the page and your issue will be resolved.
    Dismiss Notice

Oil Light

Discussion in 'Intermediate CJ-5/6/7/8' started by Billy Weidlein, Mar 21, 2022.

  1. Mar 21, 2022
    Billy Weidlein

    Billy Weidlein New Member

    Iowa
    Joined:
    Mar 18, 2022
    Messages:
    30
    Hi Everyone—going through a bunch of small and medium repairs on my 72 CJ5. The speedo combo gage works, but only speedo. The ammeter and fuel gauge do not work, so aftermarkets we’re added for those. I plan on replacing whole combination gauge once I find a suitable replacement.

    question is—after driving for 15-20 minutes, the oil light comes on on the speedo. Has done it the last couple of times I drove it.

    What does this indicate? Oil level, pressure, or something else? Dipstick says oil is full, albeit very dirty. Going to do an oil change soon, and was wondering if I should add an oil pressure gauge to monitor.

    Thanks in advance—
     
  2. Mar 21, 2022
    Billy Weidlein

    Billy Weidlein New Member

    Iowa
    Joined:
    Mar 18, 2022
    Messages:
    30
    Update—It has a separate fuel level and temp gauge, not ammeter.
     
  3. Mar 21, 2022
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,502
    Oil pressure warning light. It's an on-off switch. Oil pressure goes down as the engine temperature goes up. These engines are known for low hot idle OP at high miles. The TSM has a section on diagnosis and testing of the gauges. The '74 TSM on the Tom Collins site will be the same as a '72 in this area.

    It's not something you want to ignore. I'd connect a mechanical oil pressure gauge and see what I actually have. Good rule-of-thumb is 10 psi for every 1000 RPM minimum.
     
    Ol Fogie and Walt Couch like this.
  4. Mar 21, 2022
    Billy Weidlein

    Billy Weidlein New Member

    Iowa
    Joined:
    Mar 18, 2022
    Messages:
    30
    I’ll do that. —- that makes sense why it doesn’t come on until 10+ minutes of driving.

    The aftermarket temp gauge doesn’t appear to be working either, or it runs extremely cool. According to the gauge it ran about 160. I believe I’ll replace that as well to know/trust what temp I’m running. I had no signs of excessive temp. It does have a fixed fan, no clutch.

    we haven’t had any particular warm weather yet, mostly 50s/60s so far.
     
  5. Mar 22, 2022
    Bondo

    Bondo New Member

    Greenfield Me.
    Joined:
    Dec 17, 2021
    Messages:
    48
    Ayuh,...... Just how hot do you want it to run,..??

    160* , 180*, is a pretty good place to be,.....
     
  6. Mar 22, 2022
    Billy Weidlein

    Billy Weidlein New Member

    Iowa
    Joined:
    Mar 18, 2022
    Messages:
    30
    Cool is great—my concern was rather that I couldn’t trust the gauge and it was actually hot/close to overheating causing the oil pressure decrease.

    …..I hope it stays 160-180
     
  7. Mar 23, 2022
    Bondo

    Bondo New Member

    Greenfield Me.
    Joined:
    Dec 17, 2021
    Messages:
    48
    Ayuh,.... Then cross check it with an I/R thermometer,....
     
    Lockman likes this.
  8. Mar 23, 2022
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Hills of NH
    Joined:
    Aug 3, 2003
    Messages:
    8,493
    x2
     
  9. Apr 2, 2022
    Billy Weidlein

    Billy Weidlein New Member

    Iowa
    Joined:
    Mar 18, 2022
    Messages:
    30
    Does the oil pressure sending unit take a special socket?
     
  10. Apr 2, 2022
    Bondo

    Bondo New Member

    Greenfield Me.
    Joined:
    Dec 17, 2021
    Messages:
    48
    Ayuh,.... It depends on the sender,......

    I've gently done the deed with channel-locks before,.....
     
  11. Apr 2, 2022
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,502
    Nominally, yes.

    This is the correct part for a '74 with just the indicator light, no gauge. '72 should be the same - https://www.rockauto.com/en/partsearch/?partnum=3142826

    You're supposed to use a special socket, but a large enough 6-point socket will work. 1 1/16" I think.
     
  12. Apr 3, 2022
    Billy Weidlein

    Billy Weidlein New Member

    Iowa
    Joined:
    Mar 18, 2022
    Messages:
    30
    Thanks Guys—it was a 1”. Didn’t have a 6pt, but found an sensor socket at parts store.

    update on Issue—installed temp and oil pressure gauges. Runs about 56psi at idle cold, and drops to about 40 psi at idle at around 160ish.

    don’t have a tach, but it runs about 45-55psi through rpm range.

    seems very good I thought, was expecting it to be low. I’m guessing I had a bad sensor?—-and now I have a nice gauge…

     
    Lockman and Buildflycrash like this.
  13. Apr 3, 2022
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2022 Sponsor 2021 Sponsor 2020 Sponsor

    cordele, Ga.
    Joined:
    Mar 29, 2007
    Messages:
    5,839
    Good to go.
     
  14. Apr 13, 2022
    jeepdaddy2000

    jeepdaddy2000 Member

    Eagle Point oregon
    Joined:
    Jun 24, 2004
    Messages:
    758
    Are you still running your idiot light?
    I find a visual "aw crap" indicator to be a help when driving. I used a tee to run both my gauge and the indicator light.
     
    Ol Fogie likes this.
  15. Apr 13, 2022
    Billy Weidlein

    Billy Weidlein New Member

    Iowa
    Joined:
    Mar 18, 2022
    Messages:
    30
    I’m not currently, but that’s a good idea to tee it off and have both. I may do that when I pull the water pump and have extra room in that area.
     
    Lockman likes this.
  16. Apr 15, 2022
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb 2020 Sponsor

    Jasper Georgia
    Joined:
    Nov 24, 2019
    Messages:
    1,022
    Good idea. I have used the old " ignition key in switch buzzer boxes" from older model trucks that were used before ECM modules were invented. I simply used a ''TEE'' as you mentioned and mounted an extra indicator light sender to act as a ground to activate the buzzer with key on engine not running. You will notice the buzzer instantly if pressure fails.
    This mod saved me an expensive diesel engine when an oil pressure line failed once.
    I don't know about everyone else but I don't drive along checking my oil pressure gauge every 30 seconds. A heavy diesel engine pulling hard would be destroyed in 30 seconds without any oil pressure, chances are in major oil pressure failure you would notice the engine noise as the bearings dry out before you caught it on the gauge.
     
    Last edited: Apr 15, 2022
  17. Apr 16, 2022
    Lockman

    Lockman OK.....Now I Get It . 2022 Sponsor 2021 Sponsor 2020 Sponsor

    White City, NY 14617
    Joined:
    Dec 4, 2018
    Messages:
    2,259
    Good Idea to have mechanical Gauges on our CJ5's ...... So when you come down real Friggn' hard on the Rubicon, let's say... & you punch a hole in your pan, you'll know to shut her down right quick? Just Say'n
     
New Posts