[n86121]

On a trip to Florida with "La Wife"
about 10 mins after a normal takeoff I noted a subtle vibration.

Being the reflective mathematical sort I made the following calculations:

To keep things simple, assume 2400 RPM
Divide by that's 40 rotations per sec
4 stroke engines take 4 strokes to produce on power pulse
Or about 10 power pulses per sec from each cylinder

The vibration 'felt' around 10 hz,
suggesting one cylinder unhappy somewhere.

To land, or continue, hmmmm.

Then, after maybe 10-15 mins it cleared up.

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Now comes my annual "wallet-ectomy"

#3 cylinder, front engine, passenger side... 20 PSI. WHAT?
Borescope shows attached image for its exhaust valve.

So sad...

As you can see the valve is NOT rotating, and 20 PSI it is not closing all the way.

My gurus here tell me
The vale NOT rotating as it should,
'green edges' are from severe over-temp, aka a 'burnt offerings'

While one might be able to lap in place and pretty it all up,
the metal is cooked and WILL fracture at some point.

Sigh...

My options were
1. Have it pulled, send to shop, change vale, pretty all up and return to service $1.2k
2. Overhauled cylinder if available $1.6k - but not available!
3. Buy new $2.3k - available same day shipping

For time and value I bought a brand spanking new cylinder.
I figured project would go faster if kit IN hand.
And, I will keep the one coming off to have on hand if I need to OH it later.

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QUESTION: Mine is a turbo RSTOL = Pile 'o crap on each engine.
All that stuff is top notch great shape, but there a lot of it.

I can't complain. It is a factory new engine back in 1998 w only 600 hrs on it.
I don't fly a LOT, but do so regularly.

QUESTION 1

Any ballpark idea of how many hours to remove/replace a mid cylinder like this?
It looks like a royal pain aux derriere.

QUESTION 2

Am I over reacting? Should I just have had it lapped / ground in place to see what happens?

Your feedback, comments, reassurances and sympathies will be appreciated.