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304 Valve Train Noise

Discussion in 'Intermediate CJ-5/6/7/8' started by Ol Fogie, May 24, 2020.

  1. May 24, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

    Southern...
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    Well I got the cj5 started up. It has been sitting several years in my shop. I completly re built the carb, new points and cond, new dist cap and rotor, new wires and plugs, fresh 10w30 and filter. Cleaned out the fuel tank, new non ethanol high test and and filters. New battery and cables. She started right up on the first round. Ran it around the farm for an hour. Checked the timing and adj the air mix on the rebuilt carb. Hot oil press is 50+ above 1500 rpm and 20 at hot idle. wow it sure runs smooth for sitting 15 years and 100k miles. The only issue is there is some pecking and rattling inside the valve covers. My question is could it be the rockers are worn or could it possibly be stuck hdy lifters from sitting so long? I checked the compression, all 8 cyl were within factory spects. lowest was140 (factory spes.) and the highest was 148. Opinions please. IMG_0741.JPG
    .
     
  2. May 24, 2020
    wheelsontheroof

    wheelsontheroof New Member

    dupont pa
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    10w30 is a little on the light side for Georgia. You could try a can of stp and see what happens. The only way to be sure is to pull the valve covers . My 2012 chevy colorado gets loud with 5w30 in hot weather.
     
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  3. May 24, 2020
    Keys5a

    Keys5a Sponsor

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    Most AMC 304's (and 360's) have bridged rocker assemblies that aren't the greatest design, and the oiling system isn't the best. I usually run a "priority oil" line from the front galley to the rear galley, all under the intake manifold. These engines quite commonly make valvetrain noise once they get moderately high miles. It can't hurt to try the STP to see if that helps.
    -Donny
     
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  4. May 24, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    I will try that, I have some 15w40 rotella in the shop. I did notice the valve noise immediately when I first started it up and the oil was still cold. The noise did not change or get louder as the oil warmed up to operating temp. The noise is not terribly bad by any means it just sounds like a solid tappet motor that needs the valves adjusted. I am thinking if all is well with the rocker assemblies the hdy tappets should take up any slack in the valve train and be quiet operating. Any valve noise could only be caused by worn rocker assy bridges or poor operating hdy lifters. Am I correct in my assumptions?
     
    Last edited: May 24, 2020
  5. May 24, 2020
    Desert Runner

    Desert Runner Member 2022 Sponsor 2021 Sponsor

    Hickory, Pa
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    FWIW I would pull one valve cover at a time, start the engine and check to see if oil is coming out of the push rod at the rocker. If there is no oil or if it is very little compared to others the lifters may be sticky or stuck, causing the rods to slap the rocker. If this is the case try a new set of lifters. and check to make sure the push rods are clear of debris.
    Just my $02
     
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  6. May 24, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    It has been so long since I drove the jeep I don't remember if it had valve noise or not the last time I drove it. I always took good care of it with regular oil changes. At 36k miles the factory timing chain jumped time and was replaced with napa set which is still in it.
    That engine always ran well but from the time it was brand new it would use 1 qt of oil every 1000 miles every time. I used an oil called uniflo 10w40
    Thanks I will check them later this week and report my findings.
     
  7. May 25, 2020
    timgr

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

    Medford Mass USA
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    If this engine has not been run in a long time, I would give the new oil some time to loosen up the lifters. You could run diesel-rated oil, which has more detergent than typical motor oils (meant to wash down the excess soot of diesel combustion). If it comes to it, new lifters are not expensive, and are ok on a used cam. I would also get in there with my mechanics stethoscope and check that I'm not hearing an exhaust leak or other unexpected noises.
     
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  8. May 25, 2020
    sterlclan

    sterlclan Member 2022 Sponsor 2021 Sponsor

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    Mine had issues with the rocker bridges a few were busted. I also had casting sand in the number 8 water jacket among other troubles. Did a dingle ball rebuild and one new piston ,cam and all bearings not a problem since.
     
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  9. May 25, 2020
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    If you are talking the motor honey thick type stuff I would not run STP. It tends to gum up passages and may help with oil pressure In the short term but will create more problems in the long term.
     
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  10. May 26, 2020
    sterlclan

    sterlclan Member 2022 Sponsor 2021 Sponsor

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    I like Lucas.
     
  11. May 26, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Have any of you ever tried Rislone oil treatment added to the crankcase. I have been told it is good for freeing up stuck lifters and diesel oil pressure operated injectors. Just add a quart to the crankcase about 100 miles before the next oil change. I have never tried it
     
  12. May 27, 2020
    sterlclan

    sterlclan Member 2022 Sponsor 2021 Sponsor

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    Smells suspiciously like kerosene to me.
     
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  13. May 27, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    I thought the same thing!
     
  14. May 27, 2020
    sterlclan

    sterlclan Member 2022 Sponsor 2021 Sponsor

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    I’ve heard old timers ( even older than me ) use atf before a change to flush em out.
     
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  15. May 27, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Yeah, now that you mention that I have heard that too.
    On another thought I wonder if the ATF or the Rislone might over flush the system and remove deposits of varnish, carbon or other deposits from brg surfaces and piston and rings ect. Maybe causing excess oil consumption and increase rod and main brg clearance that might reduce oil pressure.
    Am I over thinking this!( that's what I usually do)
     
  16. May 27, 2020
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
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    With 100k miles , rockers and stands will be worn.
    I see replacement in your future.
    I remember replacing them on customers engines in the 60k mile range.
    Save your pennies for parts, not snake oil.
     
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  17. May 27, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    I wondered if that was probably what might be causing the tapping noise. If I replaced just the rockers and support stands would that probably take care of the valve train wear slack or do the valve stem ends wear and push rod ball ends wear also making them need replaced at the same time?
     
  18. May 27, 2020
    jpflat2a

    jpflat2a what's that noise?

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    Remove one or both valve covers and wiggle/rattle them around with your hand; check each one.
    You could find a broken stand or two.
    Just be careful when removing and re-installing unbroken stands.
    Only 1/2 turn for each bolt, alternating side to side; they break easily.
     
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  19. May 27, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Ah, Thank you. I have worked on this jeep a lot over the years but have never been inside the engine except to replace the timing set several years ago.
    When checking the rockers should I manually turn the engine so that I am checking them with the piston on top center compression stroke for each pair of valves, and also if replacing the with new rockers so as not to be any tension or lift on the valve?
     
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