O-320 H2AD Lifter Spalling Page

Despite a very favorable service profile, careful preheating, and frequent
lifter inspection, the engine in our 172 N has fallen victim to the sudden
lifter face disintegration that the Lycoming O-320 H2AD is especially prone
to.

Conventional wisdom is that his problem is the result of poor lubrication.
There are certainly lubrication related problems with the cams and lifters
in these engines but, after talking to a cam specialist and digging a little
deeper, I'm convinced that this failure is not a wear problem.

This issue has been around for a quarter of the history of manned flight.
It appears to be random and a survey of owners I found on the web indicates
that O-320 owners have a 50:50 chance of lifter face spalling in the first
1000 hours of operation.

Since it appears to be a mystery and other people are already looking for
Bigfoot, I've decided to start a page about it to collect information. I've
started by putting all the theories I've heard and can think of down with my
initial thoughts about them.

Contributions are welcome either by post reply or direct email (preferable).
I'll keep adding any good stuff I get. There is also a diagram of the
Lycoming valve train and photos of damaged and disassembled lifters.

The page is at:

http://baldeagleflyingclub.org/Lifters.htm

--
Roger Long