Making TBO with no top o/h

[nels]

Is it unusual for a IO360 to make it to 2000 hrs without needing the top end overhauled? I'de be nervous about losing a valve and then losing an engine. Is my concern well founded or is this just a well cared for engine. Good compressions eic but 1600 hrs since O/H.

[N201MKTurbo]

It is just getting broke in. Keep doing what you are doing.

the Lycoming engine usually fails very slowly. Catastrophic failures are rare and doing a top overhaul probably won't  change your chances much. 

 

[Piloto]

I had three IO-360 (non turbo) and all of them made it to TBO with no top OH.

José

[ArtVandelay]

I'm 1800+, another question is has anybody run them past TBO?

[Jerry 5TJ]

In my "E" I had a IO-360 that I ran until 2140 hours TT with no top overhaul. It still seemed OK, but then I felt nervous and got an overhaul.  The new engine was noticeably stronger. 

[jetdriven]

The 7/16 valve engines would snap off an exhaust valve head around 2000 hours, from what I've read. Double check what you've got, if they're 1/2" valves then soldier on. 

[ArtVandelay]

The 7/16 valve engines would snap off an exhaust valve head around 2000 hours, from what I've read. Double check what you've got, if they're 1/2" valves then soldier on. 

I thought we all have 1/2, 7/16 were on the smaller 235, at least according to SI 1037M

[M20F]

On June 4, 2016 at 9:46 AM, teejayevans said:

I'm 1800+, another question is has anybody run them past TBO?

2400 till I split the case but even then I did a repair and return.  Fix what needs to be fixed when it needs to be and don't worry so much about the hours in the log book.  It is a lot cheaper and imho safer. 

Edited June 5, 2016 by M20F

[DXB]

 FWIW, per my reading of Mike Busch's stuff, catastrophic exhaust valve failure should be a thing of the past if one is attentive to engine monitor data and routine borescope exam.  Supposedly this should pick up sticking or burning valves well in advance of failure. I take his advice, including use of his Savvy Analysis service for the engine monitor data, but I certainly don't have enough experience to endorse his viewpoint or service.  

My one and only personal data point is that the prebuy for my plane found a burnt valve and trashed guide on a 650 hr SMOH engine that got new Millennium cylinders at the time - I IRAN'd the one cylinder.   This experience made me super uptight about looking for early valve issues.  With a mind for preventing valve guide/seat deposits, I also try to watch CHTs closely, avoid running rich mixtures in cruise, and use Camguard.  Unfortunately I can't control for how someone treated my engine in the 600hrs before I owned it.

[jetdriven]

Burning valves and valves breaking off are two very different failures. A friend of mine had an exhaust valve snap off at the head and shut down 2 cylinders on a 400 SMOH IO-360. She landed in a field from 900 AGL.  

The exhaust valve stems in these engines are hollow. They run some time past 2000 hours or so before they fatigue and break off. Chuck Ney, the shop that did the cylinders, claimed they were new valves and "new valves don't last" but he never could produce a receipt or any other proof the valves were replaced with new when they redid the cylinders.

lycoming says its mandatory to replace all exhaust valves at overhaul with new  

50 hours later another snapped off, and trashed the 450 hour engine  

I guess the moral here is know who does your cylinders and verify everything. 

Edited June 5, 2016 by jetdriven

[DXB]

10 minutes ago, jetdriven said:

Burning valves and valves breaking off are two very different failures. A friend of mine had an exhaust valve snap off at the head and shut down 2 cylinders on a 400 SMOH IO-360. She landed in a field from 900 AGL.  

The exhaust valve stems in these engines are hollow. They run some time past 2000 hours or so before they fatigue and break off. Chuck Ney, the shop that did the cylinders, claimed they were new valves and "new valves don't last" but he never could produce a receipt or any other proof the valves were replaced with new when they redid the cylinders.

lycoming says its mandatory to replace all exhaust valves at overhaul with new  

50 hours later another snapped off, and trashed the 450 hour engine  

I guess the moral here is know who does your cylinders and verify everything. 

Forgive my ignorance and correct if I am wrong- I thought the two were intimately related.  Specifically, I thought the predominant mechanism of valve stem breakage was deposits and heat damage on the stem, guide, or seat preventing complete closure. I thought this resulted in hot exhaust leaking past the closed valve, which creates a feedback loop of further damage to the guide and stem. The deteriorating guide doesn't stay snug on the stem, puts stress on the it as it wobbles, and can thus cause it to snap.  The burned appearance of the valve face both suggests such damage to the guide/stem is going on and also can lead to failure from disintegration of the asymetrically heated valve face itself.

What you are referring to sounds different -either a manufacturing defect causing early failure or normal use-related metal fatigue in the stem in absence of other causative factors?

[nels]

It's good to hear these comments. I guess the reality is these Lycomings are pretty sturdy units. As long as they are cared for and run often they hold up well. It's just that assigned TBO number that always haunts me.

[gsengle]

On a separate but related topic, who has run their IO550 past tbo?

Sent from my iPhone using Tapatalk

[Jeev]

On June 4, 2016 at 7:46 AM, teejayevans said:

I'm 1800+, another question is has anybody run them past TBO?

When I bought my J in 2009 it had 1400TBO and 16 years on the IO360, in that time the logs showed two jugs being replaced.  I flew it to 2250hrs, it was still running great and performing slightly better than book numbers however I started burning about 1 qt per 3-4 hrs, getting a lot of blowby and there was oil in a few of the intake tubes so I decided to pull it in 2013.  During that timeframe the only engine work I did was spark plugs, magneto O/H and oil changes.  Like many will tell you the key to engine longevity is flying it a lot :)...  If all is good (no metal, consistent oil usage, ect) at 1600 or 2000tbo I would not hesitate to run it longer till it starts talking to you or nickel and diming you.

 

Edited June 7, 2016 by Jeev

[Guest]

If the life expectancy of a Lycoming sodium filled exhaust valve is around 2000 hours, how is it that our local flying school routinely gets 3500 out of their fuel injected 360's?  In all the time I've been on the field I don't recall them dropping a valve.

Clarence

Edited June 7, 2016 by M20Doc

[M20F]

45 minutes ago, M20Doc said:

If the life expectancy of a Lycoming sodium filled exhaust valve is around 2000 hours, how is it that our local flying school routinely gets 3500 out of their fuel injected 360's?  In all the time I've been on the field I don't recall them dropping a valve.

Clarence

You use that funny metric system up there so your 3500hrs is really only 200hrs. 

[FloridaMan]

I'm well over 1900 hours -- possibly at TBO already. #1 and #4 have been replaced. #4 was removed due to FOD destroying both spark plugs and the cylinder was found to be worn beyond limits so it was replaced; had I not had the engine failure, I would expect the original #4 would still be on there. Engine was FRM in 1995.