AMC 304 Lifter Replacement

Have a 75' CJ5 with a AMC 304. Have a stuck lifter that is not going away, inspite of my use of seafoam and marvel mystery oil. On the 304, can a lifter be removed without removing the heads? And if not, is it possible to remove tha valve cover and try to manually cycle the lifter to free it up?

 

the best/easiest way is to pull the intake manifold, not necc to remove the heads.
it could also be a broken rocker pivot, worn pivot/rocker arm, bent push rod etc.
I'd pull the valve covers, inspect, and go from there.

 

I agree with 2a. pull the valve cover and watch the push rod as you roll the motor over.

 

Big thanks...I pulled the valve cover. Cyl #1 (Front drivers side) has a "gap" between the rocker arm and lifter/tappet. I can actually "rock" the rocker arm back and forth a little. All the others are tight against the lifters. The lifter doesn't appear to be bent. Am I right in thinking this is a stuck lifter? Any other items to check?

 

Did you pull the pushrod out and see if it's bent? Make sure the rocker arm isn't bent or cracked/broken? Is it possible that the lifter is just out of adjustment?

Maybe the adjustment just backed off somehow until it was loose. Might try readjusting it per the FSM and see what happens. After all the slack is out, if the lifter compresses the prescribed amount then you might be OK. If it doesn't, then it might be a bad one.

If it was me I'd probably replace them all anyway once the intake was off, just so I wouldn't have to worry about them. If one went bad, I'd be worried about another doing it too because of oil contaminents. Cheap insurance, preventive maintenance, etc.

 

the push rod is what links the rocker to the lifter
I think if it was me, I'd pull the rocker and rocker pivot and inspect.
make sure where the push rod pushes onto the rocker arm, that area is not pushed through or wallowed out; also check the push rod ends for wear; they can wear thru the hardened ends causing play.
where the rocker pivot seats into the rocker arm, make sure the rocker arm surface isn't gaulded or overly worn with grooves.
WARNING: if you decide to remove the rocker arm, loosen the pivot bolts equally, 1 turn at a time, on both rocker arms; otherwise, the pot metal/aluminum bridge can/will break; when reassembling, the same rule applies; torque down both slowly and evenly.
if you remove the push rod to inspect the ends, make sure you wiggle it/spin it around; you don't want the lfiter to come out of it's bore , so be careful; otherwise, you might have to yank the intake to reassemble.
if all else fails, you will still have to yank the intake manifold to inspect/replace the lifter; make sure you check the bottom of the lifter as well; if sunken in or gaulded, much more work ahead.

 

if things check out ok there it could be the cam lobe is worn

 

the lifters are hydraulic and need no adjustment. depending on where they are in their cylcle the rocker may " rattle " a bit, but it should still be touching the push-rod at all times. amc v-8's are notorious for noisy (read rattleingR) ) valve train. you may be suprised to find nothing wrong at all.

how does the engine run? if it was a collapsed lifter or any other such malidy it would be runnin kinda rough/missing.

 

Again thanks....The engine seems to rev and idle smoothly..sort of sounds like an old sewing machine. Just a loud click from cylinder #1 although I have not been on the road yet....it's getting there. I am going to play with this weekend and see what happens