Re: Rocker Arm Question
It can be that the valve lash adjuster is bad. With the rockerarm removed, you can simply take the lash adjuster out by hand, or you just try to push it in by hand. A good adjuster feels hard and not spongy. It could eventualy be that it totally colapsed and bottomed out and feels hard. Best is to compare its dimension with an other one. If its ok, there is a change that the valve seat dropped. This normally causes severe damage to piston/ head/ cylinder. You could check the valve spring if its not broken. Just try to push and pull on the respective valve. There should not be any play. A bend valve stem or carbon fouled stem could also cause the rocker to fall off.
I changed the valve stem.seals on my 4.7 and made a special.tool to compress the valve spring and remove the keepers. I saw on youtube a guy who removed the rockers using a screwdriver, but at least that engine was on a stand.