This engine has a reputation for eating lifters and camshafts. We lost two
lifters and a camshaft at 1033 hours after purchasing a factory overhauled
engine and spent ten grand having the engine rebuilt. That really, really,
hurt.

I did an extensive amount of research on the lifter issue and set up a web
site to collect information. Here is what I concluded:

The early lifter problems that this engine had are not the same as it
currently experiences.

Other engines have lifter problems but lifter and cam failures are
significantly under reported in them. Lifter and camshaft damage can
progress to a startling extent before effecting performance. The performance
loss is so slow that pilots don't notice.

The H2AD has an AD that requires a check for metal that is optional on other
engines. A great feature of this engine is that the lifters can be pulled
and inspected easily. Therefore, when lifters spall, the problem is more
likely to be discovered. Other engines just go along quietly making metal
and wearing away their camshafts. Most take their worn camshafts to the
overhaul shop. A few fracture lifters or break cam shafts and stop running.

There were rampant metallurgical problems with lifters in the late 90's due
to the move to offshore outsourcing and labor/management upheavals. The FAA
will be coming out with a document about lifter problems late this year.

If you own one of these engines, you should have the lifters pulled and
inspected every second oil change. This will add about $2000 to the life
cycle cost of the engine but detecting a failing lifter early may save
removing your engine to split the case and replace a $3000 camshaft. You
should also probably put new lifters in about mid life which will add
another $1000 to the life cycle cost.

DO NOT buy a used O-320 H2AD, or any engine for that matter, without a
lifter and camshaft inspection. This will only take a couple hours with the
H2AD whereas other engines will need to have some cylinders pulled.

Make preheat your religion. Saying, "Just this once won't hurt." Can make
that $100 hamburger a $10,000 hamburger. We use an electric oil pan heater,
cowl blanket, and cowl plugs. Air head, for the length of time most FBO's
will run the heater, doesn't get the oil warm enough.

If you see a single flake of metal in your oil filter that sticks to a
magnet, especially if it is smooth on one side, PULL THE LIFTERS! Don't let
the A&P tell you that all mid life engines make some metal and you shouldn't
worry until it gets to a quarter teaspoon or so. That advice probably cost
us $10,000. After the first pinhead size piece comes out of a lifter, the
whole face come apart very fast and starts damaging the camshaft. Don't fly
the plane until the lifters are looked at.
There is a lot to like about this engine. It sends about twice as much oil
to the heads as other Lycomings and has a giant oil cooler. It runs very
cool and is not prone to valve problems.

Our engine runs very well between peak and 25 degrees LOP. All engines of
this class are prone to plug fouling so running very lean, even at the
expense of a hint of roughness, is important. For more, read:

http://baldeagleflyingclub.org/Manual.htm


The dual mag is delicate. Have it thoroughly inspected and adjusted every
500 hours, more often if anything in the engine performance changes. A good
reason for running very lean is that any problems such as induction leaks or
ignition adjustment drift show right up. Running ROP covers up a lot of
sins.

Every engine has its issues. This one may be somewhat more troublesome but
that is counter balanced by the ease of managing them. I've seen plenty of
spalled lifters in engines with mushroom lifters. It that case, you are
committed to an engine teardown. With the O-320 H2AD, it's only a two hour
job if you catch it before the camshaft is damaged.

It's a good engine for a plane flow by a lot of pilots because it is quite
hard to overheat the heads.



--

Roger Long



"Paul" wrote in message
m...
I am looking for an a/c, my first, to complete my training and to use
for recreational flying. I am looking at 172s and a book I recently
acquired (The Cessna 172 by Bill Clarke) suggests that this engine is
to be avoided.

I saw an ad in Trade-A-Plane by Factory Engines and the prices for
factory remanufactured engines are as follows:

O-320-E2D - $16,652 (this engine is the predecessor to the H2AD)

O-320-H2AD - $19,301 (the engine in question)

O-320-D2J - $16,923 (the sucessor to the H2AD)

To me this is indicative of continuing problems.

What has been the expierience of owners of Cessna 172Ns with this
engine?


Paul