Stuck valves on angle heads - Epidemic or Isolated?

[R&J Cosh]

I have recently heard of several stuck valves with bent pushrods. Since I travel a fair amount (600 hrs in the two and a half years since completing my 14A), and much of it is over unforgiving terrain or open ocean, should I be concerned? Additionally flying Young Eagles is a passion of mine and I don't want to cause undue risk.
My Lyco IO-390 Thunderbolt has not had any issues, but from what I have heard that is not an indicator of what may come. I would like to hear from folks that have had problems with stuck valves to see if there are any common practices that might be causes or remedies.
Type of flying - short, infrequent, long cross-countries
RPM and MP settings
Lean or rich of peak
Oil type
MMO used in fuel or oil
Decalin or Camguard used
Thanks in advance for your responses. I want to do anything I can to safely keep my baby flying.
Juliette
N8181J aka "Rosie"

 

[MED]

I have recently heard of several stuck valves with bent pushrods. Since I travel a fair amount (600 hrs in the two and a half years since completing my 14A), and much of it is over unforgiving terrain or open ocean, should I be concerned? Additionally flying Young Eagles is a passion of mine and I don't want to cause undue risk.
My Lyco IO-390 Thunderbolt has not had any issues, but from what I have heard that is not an indicator of what may come. I would like to hear from folks that have had problems with stuck valves to see if there are any common practices that might be causes or remedies.
Type of flying - short, infrequent, long cross-countries
RPM and MP settings
Lean or rich of peak
Oil type
MMO used in fuel or oil
Decalin or Camguard used
Thanks in advance for your responses. I want to do anything I can to safely keep my baby flying.
Juliette
N8181J aka "Rosie"

I did not have a stuck valve, but did have one failing to rotate in my Thunderbolt IO390 Exp. Discovered it using the Savvy borescope inspection routine. We monitored it over a few months, even replacing the valve rotator cap, before eventually deciding to replace the valve in cylinder #1 as it was starting to show a bit of green and the compression was dropping. I highly recommend borescope inspection as there was no other indication of a problem developing!

I fly 1 - 2 hours every week or 10 days, occasional long cross countries. Typically 65% power at 100* rich of peak. Phillips 20w-50 with Camguard. Valve replaced at 420 hours.

 

[RV6-KPTW]

Lots of info here: https://vansairforce.net/threads/sticky-valve-on-a-thunderbolt-io390.207085/

 

[turbo]

rosie, nice to hear from you. not everyone shows the interest on this subject. get educated about the health and operation of your engine. get a mechanic that knows about this stuff to. ultimately it is your responsibility to see it thru. subjects include leaning procedures, bore scoping engine, exhaust valve wobble test. good luck.

 

[R&J Cosh]

Thanks Dennis for the link. Answers a lot of my questions, and raises a few more Maybe a guide ream for Christmas.
Juliette

 

[DanH]

For the record...

Call me slow, but I just did the first SB388 inspection (the wobble check) at something over 1250 hours.



The dial indicator fixture is shop-made. Works fine, although SB388 specifies the measurement point as 3/4" above the gasket line. This fixture measures at 3/8" above. I spaced it out to 3/4" for a check; add 0.003" to the measured values below for direct comparison to Lycoming's published max wobble numbers (generally 0.030 max).

#1 - 0.022
#2 - 0.015
#3 - 0.020
#4 - 0.015

Obviously a long way from being stuck, and within max limits. Note these values were taken unkeyed, springs removed, and valve off the seat. I think it's much more accurate than shoving the assembled spring and keeper to the side.

Aeroshell 15-50, no additives. Typical cruise, peak EGT, 23 degree fixed timing, CHT 320 ~ 360. Best power climb max CHT 380F. It's never seen 400.

 

[turbo]

dan, those are some fantastic numbers. wearing as to be expected. my #3 cylinder wobbled out past 0.035 before I had a problem with it.

 

[chaskuss]

For the record...

Call me slow, but I just did the first SB388 inspection (the wobble check) at something over 1250 hours.

View attachment 72629

The dial indicator fixture is shop-made. Works fine, although SB388 specifies the measurement point as 3/4" above the gasket line. This fixture measures at 3/8" above. I spaced it out to 3/4" for a check; add 0.003" to the measured values below for direct comparison to Lycoming's published max wobble numbers (generally 0.030 max).

#1 - 0.022
#2 - 0.015
#3 - 0.020
#4 - 0.015

Obviously a long way from being stuck, and within max limits. Note these values were taken unkeyed, springs removed, and valve off the seat. I think it's much more accurate than shoving the assembled spring and keeper to the side.

Aeroshell 15-50, no additives. Typical cruise, peak EGT, 23 degree fixed timing, CHT 320 ~ 360. Best power climb max CHT 380F. It's never seen 400.

Dan my compliments on your shop built wobble tool. One suggestion for anybody considering copying Dan's tool. For the cap over the valve stem consider making it out of hex stock rather than round stock. That way you'll be able to put the dial indicator pad against the flat surface rather than a round surface.