What is the reason for the low pressures? Hissing sound from the crankcase
may indicate faulty rings or simply a rare alignment of the rings gaps. A
hissing from the exhaust ports will indicated a leaking valve but won't
indicate a reason for the leak (temporary carbon blocked). Your Mechanic
should have the answers for these symptoms prior to spending money on an
overhaul. Continentals often suffer from these symptoms. The age of the
engine and its previous storage could indicate possible corrosion due to
constant changing of atmosphere inside the case leaving condensation but
maybe a bore scope inspection will confirm or discount this possibility.
Don't overhaul a serviceable engine unless it is needed. These are simply
logical opinions based on past experince, I am not a mechanic but I would
query my mechanic if it were my engine.

Jim




"Boelkowj" wrote in message
...
Due to low pressure in 2 cylinders my mechanic says it's time for an
overhaul.
The engine is 40 yrs old and only has 680 hrs TT as it was stored for 20
yrs.
I've been flying 50 or so hrs for the past 8yrs and the engine runs fine.
It
appears that the rings are worn but also some of the leakage may be from
the
exhaust valves. Question. I plan to take all cylinders/pistons to an
overhaul
shop for complete overhaul. What usually is a typical scenario for work
done:
cylinder bore or not, new valves or not, valve guide work or not? What is
a
typical cost for the shop work per cylinder? I am hoping to keep the costs
down
and don't like surprises. Thanks

Larry/San Diego