As I said, catastrophic failure can happen, but is the exception in
engine stoppages...

Morning sickness: for example... I can't even begin to estimate the
number of engines I have heard on the ramp, at fly-in's, where ever,
that the engine starts up and shakes like a wet dog for 30 seconds
before it begins to run halfways right - yet these Einsteins just gun
the hell out of it until the valve breaks loose and go take off...

Bad rings: They start up with a big puff of blue smoke, pilot waves,
smiles, puffs out his manly chest and away he goes...

Bad mag: Uncountable times I have heard a run-up where the engine
runs rough on one mag and yet, away they go...

Dripping oil on the ramp: Hot shot pilot just jumps in and off he
goes...

And in hanging around the mechanics shop I am flabbergasted at the
condition of some of the planes brought in:
Mechanic says, 'the plugs are bad, the wires are bad and one is
broken'..
Owner says, 'well, just fix the broken wire I need to be in Pittsburg
today'...

Mechanic said: 'there's a mandatory AD on the fuel servo' (this
happened just last week)
Owner said with a scowl: 'how much is that going to cost?'
Notice that the owner did not ask and did not care what the AD was,
all he focused on was cost... After considerable discussion the
mechanic then said that he could not sign the aircraft out as
airworthy - and stomped off to work on my plane... Owner threw a fit
like a three year old... In the end he agreed to have the AD
performed... The plug on the fuel servo was finger turn loose and
likely would have put the plane into the weeds, sooner rather than
later...
This same engine has 2800 hours smoh and is burning considerable
oil... Owner refuses to overhaul it and if/when it does fail in flight
it wil be another "sudden engine stoppage" (not!)....

denny