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F134 Oil Pressure

Discussion in 'Early CJ-5 and CJ-6 Tech' started by gotime, Apr 8, 2019.

  1. Apr 8, 2019
    gotime

    gotime Sick with the car bug

    Minneapolis,...
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    My situation is as follows:
    • Completely rebuild engine with new everything including oil pump.
    • Broke in for 250 miles with Brad Penn break in oil
    • 500 miles on the engine now
    • Running 10W-30 Brad Penn
    • Not running oil filter at all. Oil filter lines are capped off, this is to prevent starvation to the #1 bearings that is common in the F134. I change oil every year and don't put on lots of miles. I don't want to start a discussion about this choice.
    • Oil pressure is about 42 psi on startup, after warm up it drops to 35 at idle and raises to 45-48 under power and RPMs.
    • Engine runs perfect with no abnormal issues.
    • Oil pressure gauge is a harbor freight mechanical one that appears to be working properly - its brand new and drops back to zero when the engine is off.
    • Outside air temp is 60 degrees Fahrenheit
    Is this about right for a brand new engine running no filter?
     
  2. Apr 8, 2019
    73 cj5

    73 cj5 Destroyer of Jeeps Sponsor

    MS
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    Per fsm

    Normal oil pressure- 35 psi @ 2000 rpm
     
  3. Apr 8, 2019
    Keys5a

    Keys5a Sponsor Sponsor

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    You numbers look very good. Most of us can hope to have pressure that high at operating temp.
    -Donny
     
  4. Apr 8, 2019
    1960willyscj5

    1960willyscj5 Well-Known Member

    Mesa, Arizona
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    You should probably re-think the oil filter thing.
    This is the first I have heard of a starvation to the #1 bearing.
     
  5. Apr 9, 2019
    PeteL

    PeteL Member Sponsor 2019 Sponsor

    Hills of NH
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    I think he's referring to very early f-heads. A smaller orifice retrofitted in the return line (timing gear jet) cures the issue, IIRC.

    But he doesn't want to start a discussion on that. :D


    EDIT: actually the jet is at the end of the oil gallery passage, not the filter return line. See posts # 26, 27.
     
    Last edited: Apr 9, 2019
    Twin2 and Glenn like this.
  6. Apr 9, 2019
    70cj5134f

    70cj5134f Member

    East Tn
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    I run 15-40,because I just polished crank, and did bearings and rings.
    Cold startup at fast idle 45-50.
    After warm up, idles 30-35. 2k bout 45.
    U r numbers look good .
     
  7. Apr 9, 2019
    Jrobz23

    Jrobz23 Member

    Northern, WI
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    Any idea what year/casting range this applies to?

    And yeah, that psi looks fine
     
  8. Apr 9, 2019
    PeteL

    PeteL Member Sponsor 2019 Sponsor

    Hills of NH
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    Not exactly. My own experience was with a 1950 pickup, many years ago. The information was in my FSM at the time.
     
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  9. Apr 9, 2019
    gotime

    gotime Sick with the car bug

    Minneapolis,...
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    Thanks for the responses guys.

    On the topic of oil filter, I discussed the issue at length with the company that did the re-sleeving and machining work (Northstar Willys - formerly Willys Minneapolis). They were very firm in their view to not run an oil filter to the point that running a filter following their engine work would void the warranty for their work. They also said they had seen many bearing failures due to the issue.

    Since they had worked on Willys longer than I've been alive, I chose to follow their direction. I didn't concoct this issue on my own :D
     
    ITLKSEZ and Glenn like this.
  10. Apr 9, 2019
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

    Tantallon, Nova...
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    Are they talking about the factory canister or an aftermarket spin on?
     
  11. Apr 9, 2019
    47v6

    47v6 junk wrecker! Sponsor

    Washington DC.
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    My first CJ2a had an Fhead in it. The front main bearing was spun when I got it. It had the canister filter, but was missing the oiler jet to the timing gear and this is what killed that main bearing as far as I could tell. Installed one when i rebuilt it and didn't have oil pressure problems. The canister filter doesn't really filter the oil like modern engines.
     
  12. Apr 9, 2019
    Keys5a

    Keys5a Sponsor Sponsor

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    The F134 factory filter setups are by-pass filters that only filter only part of the oil, as opposed to full-flow filters used on most engines from the 1960s-up. Jeep changed to a spin-on filter for the F134 around 1964, but it was still a by-pass design. The "later" style canister and spin-on filters had a return that fed an oil squirter for the timing gears. I have never heard of any bearing issues with this later design.
    -Donny
    EDIT: Howard corrected my comment above. The oil squirter is fed by an oil galley via a restricted orafice, and the return line simply dumps into the timing area.
     
    Last edited: Apr 10, 2019
  13. Apr 9, 2019
    Jrobz23

    Jrobz23 Member

    Northern, WI
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    That good cuz I found a 71 with a decent FHead that has the design you speak of.
     
  14. Apr 9, 2019
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

    Apopka, Fl
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    I'd sure like to know how/why Northstar Willys came to the conclusion the filter caused bearing failure.
     
  15. Apr 9, 2019
    PeteL

    PeteL Member Sponsor 2019 Sponsor

    Hills of NH
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    Probably because it is fed from the front of the crank oil passage. If it allows too much flow, it could drop the pressure at the bearings.

    On the other hand, how many millions of miles have F-heads racked up with that design?
     
  16. Apr 9, 2019
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

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    I suspect it was from people adding a filter to flat heads that didn't have a factory filter, a regular spin on filter & base without a flow restricter will certainly do bad things to oill pressure.
     
  17. Apr 9, 2019
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

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    These points are what I'm getting at. There would be a lot of wrecked F-heads if the original filter system itself was the problem.
     
  18. Apr 9, 2019
    47v6

    47v6 junk wrecker! Sponsor

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    Yeah it had no squirter.
     
  19. Apr 9, 2019
    gotime

    gotime Sick with the car bug

    Minneapolis,...
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    They were talking about the factory canister.
     
  20. Apr 9, 2019
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

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    Then I have no idea why they would have issues with this, frankly I think they're full of it.
     
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