I am looking into the possibility that a large number of substandard
quality
valve lifters were introduced into the supply pipeline in the late 90's.

I think the problem pre-dates the '90s, Roger.

When we were looking at Skyhawks in '97 - '98, I took one in for a pre-buy
inspection. My mechanic at the time found metal in the filter, and we, of
course, rejected the plane. He went on to say that he could not recommend
purchasing any 172 with the O-320 H2AD (I think that's the designation?)
engine because of the known lifter spalling problem.

Many will tell you that this problem has been resolved, but when you've got
$18K on the line, is it really worth taking the chance?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"