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post #1 of (permalink) Old 09-23-2000, 08:12 PM
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hydraulic lifter problems

I am rebuilding an 84 CJ7(258 engine). I replaced the cam shaft and lifters. I started it up and I heard some chattering in my valve train so I adjusted the shims underneath the rocker arms and that was a mistake. Now I need to adjust my lifter preload again, but I can not get the lifters to spring back because I am assumming that there is hydraulic pressure in them. When I first put them in they were springy now they no have spring action and thus I cannot adjust the lifter preload. Is there anyway that I can make them have their spring action again like they had when I just put them in and before I started the jeep up?
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post #2 of (permalink) Old 09-23-2000, 09:53 PM
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Re: hydraulic lifter problems

bamajeep,are you sure they are locked up and not to tight in adjustment.lifters normally do not that unless damaged frozen,ect.if they really are in hydralic lock,you have to pull them and bleed them down ,with a punch that is rounded off on the tip.i am sorry,i can not think of anything else.ranger rick

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post #3 of (permalink) Old 09-24-2000, 01:19 PM
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Re: hydraulic lifter problems

thanks but I did not mean to say thay they were locked up.

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post #4 of (permalink) Old 09-24-2000, 01:30 PM
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Re: hydraulic lifter problems

Since you usually need to remove the head to remove the lifters, you can't disassemble them to drain out the oil. If you can find the measurement needed for zero preload, you can then subtract 1/16" or so of shims to get the setting you need.

The lifters will bleed down, slowly, if kept under a load, such as that when the valve is held open. so be sure that the inner piston is fully up when you check them.

Hope this helps, good luck!

post #5 of (permalink) Old 09-24-2000, 02:33 PM
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Re: hydraulic lifter problems

I may be wrong but to the best of my Knowledge the 258 does not have any adjustment for the valves the lifters are suppose to be full of oil and not springy and perhaps the chattering you heard was the lifters that were not full of oil ,infact I think you are suppose to fill them by soaking them in oil before Installing them
maybe I am getting old and senile but that is the way I read the manual,they are suppose to hold pressure If they bleed down too fast they need to be replaced.or if they collaps = loose the ability to hold pressure for a certain amount of time.

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post #6 of (permalink) Old 09-24-2000, 02:41 PM
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Re: hydraulic lifter problems

A factory Jeep straight six doesn't require valve adjustments, but when you mill the head or block, change the cam to one that has a smaller base circle, cut the valve seats, etc., you may find that an adjustment is necessary. Aftermarket cam companies sell shim kits, adjustable pushrods, and roller rockers that fit the six and require/allow adjustments to be made.

You don't need to prefill the lifters before installation, sometimes this will cause the valves to hold open until the oil thins out and lets the lifters bleed down. A coating of assembly lube is all that is required.

Hope this helps, good luck!

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