STOH why are cylinders being replaced

[workky]

First off, I dont t own an airplane.  I take lessons right now. 

I have a real world buiness application for an airplane. So I look at them all the time.

I see an engine that had been overhauled and has 600hrs on it, and then use 100hrs STOH. Do the cylinders not last? Or is it operator error?

[ArtVandelay]

Turbo by chance? Continental?

[kortopates]

Most cylinders are prematurely replaced, often based on a single compression test. Most top overhauls are elective maintenance rather than overhauling only the 1 or even 2 cylinders that have issues. Cylinders don't typically all fail at once unless the pilot does something really out of ordinary like takeoff with cowl plugs in place and not notice the CHTs exceed limits. Check out Mike Busch webinar on All about cylinders on YouTube for a real education.


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[Yetti]

It is possible to take off lean enough to not kill the engine, but not rich enough to keep the pistons from melting.   There are several around here that found that to be true.

[Ron McBride]

I replaced all 4 on my IO360 Lycoming at about 1300 hrs. I was burning to much oil and Lycon said they were worn out, no choke left in them.

My compressions were 70+, its been a few years ago.

Ron

Edited September 7, 2018 by N803RM

[320KPH]

I read Deakin's article on Fried Valves and that has some ideas about why the tops are replaced so often. seems to be more likely on a TCM than a Lycoming.

 

https://www.avweb.com/news/pelican/182155-1.html

[carusoam]

Welcome aboard, Workky.

Instead of focusing on all the things that can go wrong...

Want to focus on on the really cool things you get out of your plane when you are in charge of setting the power and paying for the maintenance...

For Most Mooneys.... the engines can be run past TBO, the cylinders pretty much can last that long as well...

It takes the owner to decide how he wants to operate.

What you will find...

There are a few types of pilots around here....

We have the 

• Efficient ones...
• Speedy ones...
• a combination of the two....

It is possible to run all out and go really fast.... the cost will be a few gallons of fuel every hour and a top OH about halfway to TBO...

Its all up to the educated pilot how he wants to handle the finances....

If it is a business expense, you may decide to run really fast to always be on time...

As a casual pilot, you may decide running LOP and saving all the dead dinosaurs is your thing....

Read up on CHTs... the more you control them, the safer your wallet is going to be....

Practice your instrument scanning techniques... include the CHT gauge every few minutes early on in the flight...

Become familiar with the PPI... this will help you find out how the plane has been flown and what it’s maintenance status really is...

Engine monitor’s have become really helpful at doing most of the scanning and alerting for you.  You will want to have one in your plane....

What other questions do you have?

enjoy the hunt,

-a-

[exM20K]

I had the privilege of pulling and re-honing all six because of high oil consumption due to corrosion this year.

On the 231, I had one replaced at 15 hours after a factory engine was installed in 1999 or thereabouts. Bad valve seat grind.  Supposedly CMI has improved their processes a bunch since.

-dan

Edited September 7, 2018 by exM20K

[workky]

Do most mooneys come equipped with CHT instrument? We flew a 69C for quite some time. It was a fun little plane, before we crashed it.

I assume the reason for running at 55%, 65% is for fuel economy and engine longevity? I fly a crappy 172, we dont even look at all this stuff. Just push the throttle in and go

[carusoam]

Everyone gets a CHT and an EGT gauge...  one is an FAA requirement... the EGT is a Mooney thing... for efficiency...

Engine monitors that include fuel flow and total used, are just smart choices... not Mooney related.

Things that pilots do to themselves...

• run out of fuel.
• fly VFR into clouds.
• Fly IFR into thunderstorms.
• fly into icing conditions.

Use all you have to avoid these....

Go Mooney!

Best regards,

-a-

[workky]

Thanks, I'm ignorant when it comes to these things.

3 minutes ago, carusoam said:

Everyone gets a CHT and an EGT gauge...  one is an FAA requirement... the EGT is a Mooney thing... for efficiency...

Engine monitors that include fuel flow and total used, are just smart choices... not Mooney related.

Best regards,

-a-

 

[carusoam]

Go to the JPI website to see the instruments they have available...

there is also EI and insight...

Search around here for opinions....

Some people are updating and replacing old primary instruments.  Others are adding a few digital upgrades that are not considered primary....

https://www.jpinstruments.com/shop/edm-8301/

PP thoughts only, not a mechanic....

Best regards,

-a-

[Guest]

From experience I’d say Continental cylinders are junk when compared to Lycoming cylinders.  We replace so many 550 cylinders due to cracks from the fuel injector hole to the spark plug hole.  

Many others require repair due to stuck #2 compression rings.

Clarence 

[RobertGary1]

What do you mean “choke”?

i replaced a Lycoming cylinder due to high oil consumption and plug fouling. The cylinder had worn itself out of round beyond spec. 

-Robert

Edited September 8, 2018 by RobertGary1

[jlunseth]

It would be good to know the aircraft the OP is talking about, and the engine.  We are just guessing without that. The Acclaim S engine for example was doing that kind of thing with regularity.  Design flaw.  The breather exited in the exhaust, would coke up and create back pressure.  Other engines have other weaknesses. Lots don’t.  A top at 500 hours is uncommon, turbo or no.  

[0TreeLemur]

I'm enjoying reading this thread.   The logs for my aircraft show that it was given four new cylinders about 600 h. ago, only 750 h. into the current OH cycle.   Cyl #1 was replaced first, followed by #2, #3, and#4 about six months later. This was long before we bought it and I've often wondered why.   The logs don't give a "why".    From what I can gather by reading this thread, it seems likely that cylinder replacement was necessitated by incorrect engine operation more so than some material defect.  True?

[Marauder]

I'm enjoying reading this thread.   The logs for my aircraft show that it was given four new cylinders about 600 h. ago, only 750 h. into the current OH cycle.   Cyl #1 was replaced first, followed by #2, #3, and#4 about six months later. This was long before we bought it and I've often wondered why.   The logs don't give a "why".    From what I can gather by reading this thread, it seems likely that cylinder replacement was necessitated by incorrect engine operation more so than some material defect.  True?

What brand were the replaced cylinders? I seem to remember an issue with chromed cylinders - happened years ago.


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[Stephen Watkins]

     I just looked through an engine log on an aircraft that is for sale.  It has a Lycoming IO540 with around 350 hours on it. In 2017, All six cylinders were replaced with only 200 hours on them.  Why? Because the engine was overhauled in 2002 and only flown 200 hours in 15 years.  There were several times where the engine had not been flown in over 2 years.  In '17, the owner complained about excessive oil consumption.  They borecoped the cylinders and found corrosion.  All of them had to be replaced.

The THREE biggest enemies of cylinders are:

1. Corrosion - engines that aren't run corrode.  If you can't fly your plane enough, sell it, or find a buddy to fly it for you.  IMO, planes should fly at least once every two weeks.
2. Excess Heat - CHT management in climb and cruise is critical.  Obviously, engine baffling and magneto timing have to be correct, then, manage heat in climb by increasing airspeed and richening mixture. In cruise by reducing power and flying LOP.
3. Mechanics making decisions based on "Compression Tests" 

Every piston airplane owner should read Mike Busch's book "Engines" .  Link below:

  https://www.amazon.com/Mike-Busch-Engines-maintenance-troubleshooting-ebook/dp/B07D4N1LQ1/ref=sr_1_1?s=digital-text&ie=UTF8&qid=1536544489&sr=1-1&keywords=engines+mike&dpID=41N2Ug7AaTL&preST=_SX342_QL70_&dpSrc=srch

 

Edited September 10, 2018 by Stephen Watkins

[0TreeLemur]

12 hours ago, Marauder said:

 

What brand were the replaced cylinders? I seem to remember an issue with chromed cylinders - happened years ago.


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The logs don't give manuf. or reason for replacement.  The a/c was flown at a rate of 80-100 h/y during this period.  There is mention to an AD regarding cylinders but the note is that it did not apply.