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94x4 · 07-05-2005, 11:36 AM

The valve lifter, or hydraulic lifter (although it's operation is purely mechanical), or even camshaft follower, is basically a little cup that sits atop the valve, with a shim of varying thicknesses on top of it that acts as a spacer for the cam's lobe to ride on.

Normally the lifter itself does'nt "collapse", instead, the shim becomes worn and needs to be replaced with a new one of proper thickness, which is determined with a feeler gauge and some plasti-guage.

It is also common for a spring to have "collapsed" or broken, but your problem is probally just that the shims need to be adjusted, a "scheduled maintenance" item suggested to be performed every 60,000 mis.,
or every 2 yrs., whichever comes first, which will definitely cause a "loud knocking" at the top of your engine.

Just a little clarification to avoid confusion, so ask your "mechanic...friend" about this and let's know what he comes up with.

07-05-2005, 11:36 AM	#7 (permalink)
94x4 Guest Join Date: Jun 2005 Posts: 1,429	The valve lifter, or hydraulic lifter (although it's operation is purely mechanical), or even camshaft follower, is basically a little cup that sits atop the valve, with a shim of varying thicknesses on top of it that acts as a spacer for the cam's lobe to ride on. Normally the lifter itself does'nt "collapse", instead, the shim becomes worn and needs to be replaced with a new one of proper thickness, which is determined with a feeler gauge and some plasti-guage. It is also common for a spring to have "collapsed" or broken, but your problem is probally just that the shims need to be adjusted, a "scheduled maintenance" item suggested to be performed every 60,000 mis., or every 2 yrs., whichever comes first, which will definitely cause a "loud knocking" at the top of your engine. Just a little clarification to avoid confusion, so ask your "mechanic...friend" about this and let's know what he comes up with. Last edited by 94x4; 07-05-2005 at 11:42 AM.