So I have been thinking ahead (hopefully long long ahead) to when it will be time to either overhaul my O470R or replace it. Over its life it has had a top overhaul once already before I bought the plane. I'm thinking that when it comes time to make a decision that I would do the popular PPonk upgrade, and according to their website they can build one of their engines starting with an O470 case. That would seem to be the way to go cost-wise since I already have the engine, however I know all metal has a fatigue life and I wonder whether I would be asking for premature trouble if I used my current engine for a rebuild or should go with a new one? Anyone have any thoughts on this?

What is TT on the bottom end?

About 3500 hours

NMXWinds wrote:About 3500 hours

If the bottom end parts pass inspection you may be OK. What is calendar time on the botton end?

Same age as the plane. Both born in 1974.

I'm no mechanic, but I've gathered some info over the years that I believe is reasonably accurate.

First, if it has 3500 hours on it, it's most likely had more than a top overhaul, most likely a complete overhaul and perhaps a top in addition since that complete overhaul. My recollection is that the O-470 has a TBO of 1600 hours, and many successfully go beyond that--but not to 3500 hours. Most need a top on one or more cylinders at about the 1000 hour mark or so. So you might want to go through the engine logbook and see what happened and when, as you plan for the future.

Second, it's not unusual to use a case through several overhauls. As long as it meets Continental's specs and has no cracks or other anomalies, it's still usable. I'd rely on a good engine shop to tell me whether the case is reusable, not on the number of hours but on its condition at the time. Certainly don't rely on any Internet advice! Although it's true that you can often get some pretty good advice here because there are some really knowledgeable people here, they haven't seen your engine or its logs. And the only real way to know if you'll need a new (or used) case other than what you have is for your engine builder to take your engine apart, examine it, and measure whatever needs measuring.

So until it's time to do something based on condition, you won't have enough information to make a decision. Meanwhile, save your pennies, because whatever route you go won't be inexpensive.

Cary

Steve Knopp & co. seem to enjoy a good reputation, and I doubt they'd want to put their name on a worn-out core. Why not ask them?