Many of the low time engines were last cracked open more then 20 years ago...so these engines (according to this forum) are pretty much toast.
There are those on the forum that agree with you 100%. They would never consider an engine that hasn't been opened within recommended intervals, regardless of apparent condition. As an experienced mechanic, I'm a little more subjective than that.
Of more importance is how often the engine is/was flown during that extended period. Consider that an engine that is religiously flown for one hour once a week since new/overhaul for 20 years has accumalated only 1,040 hours TSN/TSOH over that extended period! This engine is very likely in better shape corrosion and reliability wise than a zero time engine that was factory overhauled and then hung on the airplane and left sitting dormant for two years! I would not disturb the properly operating 20 year old overhaul, but the 2 year old zero TSOH engine may require corrosion repair! Age alone does not ruin an engine, although it may indicate a need to closely inspect seals and gaskets, etc., which can dry out and become brittle. Most "soft" parts can be replaced successfully and inexpensively without overhaul. To the casual buyer, age is a concern, but it doesn't mean that all such engines are bad news. It does mean it will take considerably more than a leakdown check to determine the condition of an engine which has remained dormant for an extended period. A properly preserved and dehydrated engine can remain pristine indefinately with proper maintenance, but this is unfortunately rare. Still, a good number of engines are reliably flying today after years of inactivity with little more than an oil change required for continued operation. At a minimum, a suspect engine should be borescoped internally for corrosion and sludge; seals, gaskets, and hoses inspected for condition; the carburetor and gascolator removed and internally inspected for corrosion from standing water, etc., aircraft fuel system drained and flushed, .... you get the idea. Chances are that the need for overhaul or repair will be discovered during the process, but sometimes a real gem can be had at a steeply reduced price when you know what to look for! Detailed indepth pre-buy or annual inspections are paramount when considering purchase of a stagnant airplane. Sometimes a deeply discounted purchase price will allow economical rebuild of a "project" airplane.
While I agree that the odds are good that any engine that hasn't been flown regularly or recently may have hidden corrosion and other problems, each engine and it's history should be examined on it's own merits. Regardless of where, when, and how an engine was overhauled, or TSOH, you're buying a "pig in a poke" in every case until it's been thoroughly inspected and performance and reliability proven.
I have not covered all of the bases here! This is not a recommendation! Just food for thought!
Looking to get a 150 myself in the next little while.
