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225 Engine miss and low oil pressure

Discussion in 'Early CJ5 and CJ6 Tech' started by PostaljeepSS, Jul 11, 2011.

  1. Jul 11, 2011
    PostaljeepSS

    PostaljeepSS Member

    Boise,ID
    Joined:
    Jun 22, 2008
    Messages:
    86
    Good evening. I finally got around to getting the '46 out yesterday but it seems that winter took it's toll. There's a slight miss at idle which isn't too big a deal but from off idle through the rest of the band it starts missing pretty bad and backfires when throttle is returned to idle. I changed the plugs/wires and ran some carb cleaner through with a fresh tank of gas but it didn't seem to help. There's no noticeable smoke but it does smell a bit like unburned gas. I reied advancing and retarding the timing a bit incase the mark was off or the gears were work but it made no appreciable improvement. I gave it an oil change before starting it up and once it was running I noticed it's got 20lbs of oil pressure cold and hot at idle. Revving up the engine the pressure only rises to 22-23 lbs which worries me a bit. I tested with another gauge which confirmed the same reading. At this point I'm thinking there may not be enough pressure to keep the lifters pumped up which is leading to the miss. I replaced the oil pump late last year and I remember it working OK but maybe the bypass has gotten stuck?. Any thoughts on this would be greatly appreciated.
     
  2. Jul 11, 2011
    Patrick

    Patrick Super Moderator Staff Member

    Los Alamos, NM
    Joined:
    Sep 22, 2002
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    8,372
    First off, if the lifters are collapsed enough to cause a miss, they'll be clattering/ ticking pretty loudly...
     
  3. Jul 12, 2011
    SFaulken

    SFaulken Member

    Renton, WA
    Joined:
    May 24, 2011
    Messages:
    646
    Yeah, you'll hear the lifters before you hear anything else. If it isn't an *obvious* clacking noise*, I'd start with looking at the oil pressure, if that's low, go pick up a new high volume pump (not high pressure, HIGH VOLUME), in the grand scheme of things 10 psi per 1000 rpm is fine. High pressure isn't going to do you anything. I just wish we all had access to a flow meter. What is flowing through the motor is far more important than at what pressure that oil is moving at....
     
  4. Jul 12, 2011
    Stout

    Stout Member

    Quakertown, PA
    Joined:
    Nov 1, 2010
    Messages:
    958
    What was your oil pressure last year when it was running right?

    If it is backfiring returning to idle from higher revs, it sounds like timing or ignition. You mentioned you changed your plugs and wires but what about points and distributor cap? Condensation or cracks in your dist. cap could also cause those symptoms.
     
  5. Jul 12, 2011
    billybbean

    billybbean Member

    Kemmerer, Wyoming
    Joined:
    Apr 29, 2010
    Messages:
    55
    "There's no noticeable smoke but it does smell a bit like unburned gas"

    Sounds like a carb issue to me. If it sat over the winter the fuel probably evaporated out of the carb and left some junk where it shouldn't be. I would check the tubes on the venturies. Make sure all the little holes are not obstructed.
     
  6. Jul 13, 2011
    mdmeltdown

    mdmeltdown Member

    Bossier City,...
    Joined:
    Feb 17, 2006
    Messages:
    791
    They may be 2 unrelated issues. I'd be willing to bet the diaphram on your accelarator pump swole up from sitting in the new E10 or E15 gas. I was having the same problem and the carb guy put in 3 different pumps untill we found out the old school leather ones were not affected by ethanol
     
  7. Jul 13, 2011
    PostaljeepSS

    PostaljeepSS Member

    Boise,ID
    Joined:
    Jun 22, 2008
    Messages:
    86
    Thank you for the advice so far! I had not replaced the cap and rotor yet. So I picked them up today for a 66 CJ-5 with delco distributor ($15 for both). I ran into a bit of a snag here though, The cap does not fit properly. I included a picture of the 2 caps. The one on the right is from the jeep and the one on the left is the new one.
    [​IMG]

    The cover location hits the vacuum advance housing so it won't sit level and the retention screws can't hold it down. The cap that came off the jeep has delco stamped in the plastic so I believe I asked for the right part. I took the one I got back and asked to see another one, which was the same as the one I got. Could this be a symptom of being made in China or is something amiss here? Here's a picture of the distributor. Maybe it's not a stock vacuum advance?
    [​IMG]

    I picked up a rebuild kit for the carb so I'll get started on that in the meantime. I just did one last summer too...
     
  8. Jul 13, 2011
    Patrick

    Patrick Super Moderator Staff Member

    Los Alamos, NM
    Joined:
    Sep 22, 2002
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    There are two different caps, as you have found out. Use the search function here and you'll find the part numbers as this has been discussed. I used to have the numbers....
     
  9. Jul 13, 2011
    PostaljeepSS

    PostaljeepSS Member

    Boise,ID
    Joined:
    Jun 22, 2008
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    86
    I'm finding lots on HEI but this appears to be a points system. I'm fine with looking for the answer but don't know what keywords I'm needing to find it.
     
  10. Jul 13, 2011
    Patrick

    Patrick Super Moderator Staff Member

    Los Alamos, NM
    Joined:
    Sep 22, 2002
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    Yeah, I looked briefly and didn't find it. Call or stop by your local parts store and have them look it up. There should be two numbers.
     
  11. Jul 13, 2011
    PostaljeepSS

    PostaljeepSS Member

    Boise,ID
    Joined:
    Jun 22, 2008
    Messages:
    86
    Ok, I returned the cap and and asked the guy at O'Reilly and they only list the one model I got. Autozone has 1 model for a CJ5 Universal and 1 for CJ5-A. The 5A model they can't even get. NAPA is closed now but I guess I'll check with them tomorrow.
     
    Last edited: Jul 13, 2011
  12. Jul 13, 2011
    Patrick

    Patrick Super Moderator Staff Member

    Los Alamos, NM
    Joined:
    Sep 22, 2002
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    8,372
    CJ5A is just a Tux. Shouldn't be a different cap for that. What part number did you have?
     
  13. Jul 13, 2011
    PostaljeepSS

    PostaljeepSS Member

    Boise,ID
    Joined:
    Jun 22, 2008
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    86
  14. Jul 13, 2011
    Patrick

    Patrick Super Moderator Staff Member

    Los Alamos, NM
    Joined:
    Sep 22, 2002
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    I have an Airtex 4R1250 here..FWIW..
     
  15. Jul 13, 2011
    PostaljeepSS

    PostaljeepSS Member

    Boise,ID
    Joined:
    Jun 22, 2008
    Messages:
    86
  16. Jul 13, 2011
    Patrick

    Patrick Super Moderator Staff Member

    Los Alamos, NM
    Joined:
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    That's the thread I was looking for.
     
  17. Jul 22, 2011
    babyboomerboy

    babyboomerboy New Member

    Kansas
    Joined:
    May 22, 2011
    Messages:
    23
    Had the very same problem as described above. The correct distributor cap for your 225 is NAPA # RR189
     

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