Wondering About Top

[Alan Maurer]

Hello Mooney People,

Ovation has. about 1000 hours on IO 550 G and have thought about  top overhaul. Also have read Mike Busch's essay " Cylinder work: Be Afraid. "

Folks at Sarasota Avionics (KVNC) do these often but don't necessarily follow Mike's ideas...ie, preloading, torque precision etc. Using about one quart oil every 3 hours.

Would like some thoughts

Thanks

Alan...N913ND 

 

[A64Pilot]

Top overhauls are common on Continentals.

There have been issues, but usually when only one cylinder has been replaced and mechanic doesn’t see the need to remove all the baffling etc to torque the other side of the thru bolts. When all cylinders are replaced there is much less problems because ALL nuts are torqued.

But you don’t turn the prop, with the jugs off. I think some used to and still may because it’s a lot easier to get the piston in with the rod fully out. If you turn the prop there is a slight chance that you may unseat a main bearing.

‘If they do them frequently there should be no issue, But I think I would use an Engine shop, never used them myself but have heard good things about Zephyr Hills.

[GeeBee]

I have an IO-550G with about the same time. I've replaced one cylinder due to a crack from manufacturing defect noted on the recent AD and one at about 800 hours due to leaking exhaust seat.  I burn a quart every 11 hours consistently.  Are you running your oil level at 6 to no more than 7 quarts? Do you fly once a week? What power setting due you normally run at and LOP or ROP?

I also find it highly unlikely you would need to do all the cylinders and that all the cylinder are pushing oil unless you have been flying through sandstorms.

 

[Alan Maurer]

Hi GeeBee, Fly at least weekly, oil level kept at seven, fly ROP 23 inches and 2400 RPM. Annual in July. no sandstorms. Probably compression low (fifties) on at least one cylinder, Boroscope did not show any valve damage. looked ok. Not really anxious to do anything. Engine develops full power on take off and runs smoothly. Sarasota Avionics suggested a top but I am not convinced to do anything 

[GeeBee]

Sounds like you're running at 75% which is going to shorten cylinder life. Why don't you run her at 65% take your oil level to 6.5 and see what happens.

I generally take mine to 9,10 or 11 and run WOT and that is 65%. WOT at 9 and above is the real sweet spot for the engine.

 

[N201MKTurbo]

Cylinders rarely fail catastrophically. They just slowly fade away. Even when the oil consumption is ridiculous, they will still make power. It usually comes down to being too annoying because you have to add too much oil or clean the plugs too often. 

[Alan Maurer]

Thanks Everyone,

Annual in July...will pan to horoscope the cylinders and have a look...not at all anxious to do anything else now as long as the cylinders look fine.

[Vance Harral]

50 minutes ago, Alan Maurer said:

horoscope the cylinders

I know it's a typo and I should just let it go, but... that may be as effective as any other inspection method!

[N201MKTurbo]

2 hours ago, Vance Harral said:

I know it's a typo and I should just let it go, but... that may be as effective as any other inspection method!

Sometimes the spell checker knows more than we do…

[MikeOH]

6 hours ago, Alan Maurer said:

Thanks Everyone,

Annual in July...will pan to horoscope the cylinders and have a look...not at all anxious to do anything else now as long as the cylinders look fine.

Just make sure you get your palm read before the plane gets its horoscope

[Echo]

Learning something. I always thought it was whorescope?

[rickseeman]

On 6/5/2023 at 3:26 PM, Alan Maurer said:

Ovation has. about 1000 hours on IO 550 G and have thought about  top overhaul.

I find that strange. I have never "thought" about a top overhaul. If my airplane isn't jumping up and down and screaming, I wouldn't top anything.

[KSMooniac]

1 hour ago, rickseeman said:

I find that strange. I have never "thought" about a top overhaul. If my airplane isn't jumping up and down and screaming, I wouldn't top anything.

Don't worry, your plane has an excess money detector and it will eventually go off!

[Alan Maurer]

Hi Everyone, Thanks Everyone, Annual next month. Will Boroscope cylinders and then consult Psychic Palm Reader and see what the stars say. 

Airplane is not jumping and screaming and I am not in any hurry to do anything to the engine. At 1000 hours , cylinders are not in the seventies but this is a

Continental so no surprise. I appreciate everyone's input especially the funny ones. 

Thanks

Alan ....Ovation N913ND

[A64Pilot]

For a Continental that’s been run hard it’s pretty common for it to need cylinders prior to overhaul and while 1,000 hours may sound short it’s not uncommon at all.

I understand why many run them hard, they bought the big motor Mooney to go fast and it only goes fast if run hard, it they wanted to loaf around they would have saved money and bought a J.

From my limited experience it’s uncommon for a 550 to make TBO on one set of cylinders, and if your having to change cylinders before TBO the halfway point is a logical place to do so, because it’s unlikely your overhauling an engine and not at least re-working the cylinders.

I’m not saying change them at 1,000 hours, just saying if you have to I don’t think your the Lone Ranger.