I've had a little experience with my 150 regarding an older overhaul and a plane that sat for quite a while. Hopefully it'll give you some insight regarding your concerns for the overhaul in 1989.

The engine on my 150M is currently at 1716 SMOH. That overhaul was performed in the 1982/83 timeframe and is the only overhaul this aircraft has seen. She flew a lot in the 80s and 90s, even the early 2,000s. Then she sat for a while (6 years actually) after a previous owner passed, but annuals were maintained for the first 3 of those, and the most recent owner before me didn't fly it much once he put it back together (he didn't even have an annual done in 2013).

Cylinder 3 compression was 67 at annual last August. The other cylinders are mid-70s. Aside from replacing a few exhaust valve springs (weak because it had sat so much) and cylinder head gaskets, I haven't really needed to have much done to the engine "core" itself. I did need to have some ignition work done - replaced mags, plugs, & harnesses a couple years ago. Also replaced the muffler at annual last year. Now I'm finally to the point where I've been doing little upgrades here and there - Stratus Power in the panel at annual, and an LED landing light back in February for example.

It'll be a year, maybe two, before I reach TBO, and for now, I don't see anything in the engine's performance that tells me I need to be in a hurry to overhaul.


Having said all that, this Bonanza Fever thing must reeeeally be contagious. I hadn't even read this thread yet, and for the last two days I've been looking at some of the older models on Trade-a-Plane. Must be something in the air (pun intended).

States I landed in N63420 while he was mine:
[Linked Image from visitedstatesmap.com]
KDCY

"Flying a plane is no different from riding a bicycle. It's just a lot harder to put baseball cards in the spokes." - Captain Rex Kramer