Lifter tick

[Phil Payne]

> I've never seen one so worn it needed to be replaced. The tick is caused by
> slowed or absent hydraulic action, and the hydraulic portion is not subject
> to wear, just clogging or lack of oil flow.

I must have replaced a dozen sets this year.

The main symptom is a cyclic click.  The cam lobes are not directly over the centre of the
lifter, so each encounter between cam lobe and lifter imparts a tiny turning force to the
lifter, spreading wear over the top surface.  You can see this in the patterns on top of the
lifter.

If you have a tick that cycles (ca. 0.2Hz) on and off it's a worn lifter.  The basic reason is
that the pressure oil feed comes from one side of the block, and the rotating lifter
alternately has its hole facing the feed (pumped up) and on the opposite side (less pressure).

Yes, they do wear - but not that much.  My 297k engine is coming to end of life on its second
set.

-- 
  Phil Payne
  http://www.isham-research.com
  +44 7785 302 803