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  •  » Oil pressure drop after warm up...

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    12/11/2017 8:08 PM  #1

    cgomate
    FYI Addict

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    Registered: 4/01/2013
    Posts: 130

    Oil pressure drop after warm up...

    Greetings from San Diego...

    ​I drive the car (67 cpe, 289, C4) to work about 3 days a week and have an oil pressure problem.  The idling oil pressure at start up never goes above 40 psi. By the time I get to work (15 miles on freeway) the pressure drops to 5-7 psi at idle.  

    ​Aftermarket oil gauge & sender are new. I noticed a similar trend with the factory gauge before I replaced it... so I'm assuming its not that.

    ​There's no visible smoke coming from the exhaust, but there is a strong smell to it.  The engine also consumes about 1 qt of oil per month with NO exterior drips of any kind.

    Engine runs smoothly & seems strong, but obviously something isn't right. What are the possible issues and how can I diagnosis this?

    ​mm
     

     

    12/11/2017 9:45 PM  #2

    MS
    Forum Originator

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    From: Canyon Lake, Texas
    Registered: 1/24/2013
    Posts: 12,345

    Re: Oil pressure drop after warm up...

    Oil pressure drop and oil consumption are not really related, other than they both are typically the result of a worn out engine.

    Pressure drop
      Worn bearings (most likely the cause)
      Bad oil pump
      Clogged oil pickup
      Bent oil pan
      Oil pickup too close to oil pan
      Clogged drain holes in the heads, restricting oil draining back to the pan.

    Oil consumption
      Worn rings/cylinder bores
      Bad valve seals/guides
      Intake manifold gaskets leaking
      Missing baffle under the PCV valve in valve cover
      Massive oil leaks

    If it still runs good, oil is fairly inexpensive...
    I would not waste time or money trying to bandaid the pressure problem. Sounds like a rebuild is about due.

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
     

    12/11/2017 10:19 PM  #3

    lowercasesteve
    Senior 24-7 FYI Addict

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    From: Auburn, Ca
    Registered: 4/01/2013
    Posts: 1,261

    Re: Oil pressure drop after warm up...

    You  might be ok.  Our engines get 10psi per 1000 rpm.  What you are seeing is close to that.  Pressure  will be higher when it is cold.  Reducing as it heats up.

    How does the pressure look when you are running?  ​If you are getting 5-7 psi while running, you should not run it at  all.  MS's recommendations are spot on as usual.

    Original owner - 351w,T-5, 4whl disks, power R&P
     

    12/11/2017 11:41 PM  #4

    6sally6
    Hyper FYIFORD ADDICT

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    From: Surfside Beach,SC
    Registered: 4/02/2013
    Posts: 6,899

    Re: Oil pressure drop after warm up...

    Sounds like you, my fellow MS'er, are suffering from  "General Motors Chevititus"! Most GM's run a higher oil pressure than Fords because their engine oiling systems are not as efficient as Fords.
    Since most publication worship at the alter of "Chiva-laze" they spew out the words that  20-30# oil pressure is "the norm" for  ALL engines. Jus' taint true on fords.
    Now....when the oil light starts "winking-at-you-" when stopped at a red light.......then is the time to get corn-serned!
    No kidd'in......sounds like you have a "well broken-in" SBF engine.  No worrys....yet!
    Think of it this way........your rod and main bearings are opening up because of wear so NOW you have less parasitic drag going on in your engine!!!
    NASCAR spends millions trying to find what you have going on RIGHT NOW!!!!
    6sally6

    Funny off-topic story.....Buddy of mine(several years ago) was talking about the new tachometers with the shift light. You set the RPM you want to shift at...and the light will come on at that RPM. He sez..."ain't nuth'in new about that!" I've had that fer years. I like to "pin-that-pedal" and when that oil lights..... juuuust starts to stay on steady....I know its time to "catch-another-gear!"
    Max RPM every time!!!

    Last edited by 6sally6 (12/11/2017 11:59 PM)

    Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
     

    12/12/2017 6:27 AM  #5

    RickD
    FYI FORD Member

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    Registered: 4/03/2013
    Posts: 17

    Re: Oil pressure drop after warm up...

    I am showing my age here, but I remember when the 65 Mustangs came out, it was common (on the 289) for the oil pressure light to come on while idling at a stop light.  In fact that may have been one reason why they changed to a gauge in 66.

     

    12/12/2017 8:00 AM  #6

    Bullet Bob
    Senior 24-7 FYI Addict

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    From: Montrose, Colorado
    Registered: 4/01/2013
    Posts: 4,896

    Re: Oil pressure drop after warm up...

    The 154K mile '90 GT that I bought from my brother would drop to around 10 psi at idle when hot.  I axed my bro about it and he said it had been doing that since new.

    BB

    "you get what you pay for, good work isn't cheap, and there are NO free lunches...PERIOD!"
     

    12/12/2017 9:09 AM  #7

    Rudi
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    From: Stuck in the 50's Welland Ca
    Registered: 4/01/2013
    Posts: 3,992

    Re: Oil pressure drop after warm up...

    How many miles on the engine?

    Good work ain't cheap, Cheap work ain't good!   Simple Man
     

     

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