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  1. #1
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    Default Hydraulic roller lifter preload and bleed down

    Hi everyone - I have a bit of a question about my crane hydraulic roller lifters - 24533-16
    I'm a bit rusty on hydraulic stuff cus i have only used solids for the last 10 + years but here goes -----
    After a fresh build and a brief run in period I decided to check the lifter preload recently and noticed that some ( about a third ) of the lifters offered very little/no resistance after the lash was taken out and I was into the preload stage - like they has collapsed completely? I had just changed the manifold so the engine had not been run for about 24 hrs- is this an issue? do I need to set preload just after the engine has stopped ????
    Thanks for your help in advance
    JOEL

  2. #2
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    do it cold. I always just have each cylinder on compression so valves are closed loosen the rocker adjuster and just shake rocker back and forth till there is no slop then 3/4 turn more then lock up the adjuster thats is some people only have 1/2 turn preload.

  3. #3
    been here .......too long Smitty2's Avatar
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    Quote Originally Posted by beetle123 View Post
    do it cold. I always just have each cylinder on compression so valves are closed loosen the rocker adjuster and just shake rocker back and forth till there is no slop then 3/4 turn more then lock up the adjuster thats is some people only have 1/2 turn preload.

    yup.... I use the 1/2 turn on the race car
    or you can REALLY go to lengths and measure 60thou height crush against the lifter body
    (recommended by most manufacturers EXCEPT with antipump up lifters)
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  4. #4
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    Is it normal to have some of them give nearly no resistance when setting the pre load though ??????

  5. #5
    Part of the furniture monaroman76's Avatar
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    That's normal. Some lifters may have had more oil in the oil cavity when you were preloading them (depending on how much preload they had initially). The force required to overcome the internal spring alone is not great.

  6. #6
    Do you ever leave? EH179's Avatar
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    Is the valve train noisy when operating?

    You could also cut the roof off a pair of rocker covers and bolt them on.
    Start engine and back off each adjuster nut until they just start ticking, then tighten until they just quieten down and stop.
    Repeat for the rest of the rockers and consider the pre-load done.

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    Quote Originally Posted by greasemonkey View Post
    Is it normal to have some of them give nearly no resistance when setting the pre load though ??????
    Yes,those were the lifters on open valves...all the oil pushed out.

  8. #8
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    No EH179
    Not noisy at all - I just want to be sure everything is OK
    Thanks
    Last edited by greasemonkey; 06-01-2019 at 11:07 PM. Reason: cus

  9. #9
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    Quote Originally Posted by 71rocket View Post
    Yes,those were the lifters on open valves...all the oil pushed out.
    Hi 71 Rocket
    So this is completely normal ??? It does make sense that they would bleed out - I just wasn't sure how long this should take
    Thanks for the reply mate - I feel a little more at ease now

  10. #10
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    I have the same thing. Some were tight adjusting in. Others you could almost push in a bit by hand. Pumped up fine with no noise.

  11. #11
    Part of the furniture monaroman76's Avatar
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    Yes this is normal. All lifters have clearance between the plunger and the lifter body so they can compensate for thermal expansion and "re-adjust" from one cycle to the next to maintain zero lash. You're all good

  12. #12
    Part of the furniture monaroman76's Avatar
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    According to my quick calculations. The lifters will bleed down in about 60 mins. I'm happy to share how I came to this number if you're interested

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    Many factors to consider with lifter bleed down rates: oil viscosity, internal piston/body clearance, spring rate, rocker ratio. Thin[ner] oil, stronger springs & higher ratio rockers with bleed down the lifters more quickly.

    I know this thread is about roller lifters, but here is a tip about Flat Tappet lifters. As many are aware, there have been a spate of FT lifter/lobe failures since the early 2000s. The reduction of Zn & Ph in the oil got blamed. The oil companies saw a marketing opportunity with 'new' oils. It is not the oil, never was. Problem was crap quality lifters, soft.

    If you want reliable lifters, have your factory or pre-2000 lifters re-faced. Contrary to popular belief, they are the same hardness throughout & can be refaced 2-3 times. Clive Cams in Vic does a superb job.

  14. #14
    Part of the furniture monaroman76's Avatar
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    Quote Originally Posted by GtoGeoff View Post
    Many factors to consider with lifter bleed down rates: oil viscosity, internal piston/body clearance, spring rate, rocker ratio. Thin[ner] oil, stronger springs & higher ratio rockers with bleed down the lifters more quickly.
    Spot on. I just used some assumptions to come up with my calculation. 200lbs spring pressure, 1.65 rockers, SAE 50 oil, 0.1 thou plunger/body clearance. Then I just used leakage flow calculations for an annular control area around a spool.

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