Collapsed Lifter-318

Approximately 10/14/03 12:51, snipped-for-privacy@nospam.org uttered for posterity:

In a hydraulic lifter, perhaps it would help to think of the lifter itself as a shock absorber. It fills with engine oil in operation. There is a check valve to keep it from leaking that oil out... dirt in the oil can keep the check valve open, at which point the lifter will "collapse". The lifter operates the valves thru a pushrod, but it isn't a full metal chain of motion, the oil inside the lifter is what actually carries the pressure to move the valve.

Kinda depends on the engine, but with a thoroughly collapsed lifter, that particular valve will not open.

If really bad, you should be able to hear a chuff or whoosh sound.

Otherwise, it will be a ticking. Sometimes you can get it to go away by changing the oil, getting the engine hot, then change the oil again...usually with Marvel Mystery or a really strong detergent additive. Usually lifters that are just a bit weak or dirty may be noisy only when the engine is cold or right after a hot start.

If you try to adjust this lifter, no matter how much you tighten it, the clicking will not go away. Note that a loose adjust sounds pretty much like a mildly collapsed lifter. You can usually hear them better with the valve cover off.

If the check valve is defective rather than dirty, this won't help.

Depends on the engine. On some you can use a magnet to pull the old lifter out.

They aren't that expensive.