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Morning sickness?

RV10Rob

Well Known Member
My engine runs rough for 20-30 seconds after cold start. Based on the sound in the video and the EGT chart, could this be a sticky #3 exhaust valve? Note the CHTs appear normal. Engine is an Aero Sport IO-540-D4A5 w/ Lightspeed Plasma + Slick Mag. 230 hrs SNEW. Thanks for any advice.

-Rob

Video:
http://www.youtube.com/watch?v=ZMmbXTWGqqk

EGT chart:
file

x axis is seconds since start. y axis is EGT
 
Last edited:
Probably not. Seems not unlike mine.

C1 for us is always out of the pack when not running at anything more than 900RPM. And we have checked lifters etc etc.... Just the way it is. And 820 hours or so later....

Just keep an eye on the data over time for any trends. I have seen induction leaks do funny things as they come and go from cold to warm to hot. And 250 hours was about the average for the life span of the black coloured gaskets. Red superior ones have fixed that.
 
This was a new thing (EGTs used to be normal, and also no roughness). I checked the exhaust valve, and there appears to be a good amount of "wobble".
http://www.youtube.com/watch?v=Ko-zd9w3s9Q

I'm going to get a tool to measure it properly. I also checked the plugs and injectors, and the intake gaskets appear to be okay, so I'm stumped. Aero Sport didn't have much new to add, other than to say the exhaust valve sounded like a good place to focus.

-Rob
 
Rob,
that's quite a wobble!
Visible without micro measurement tools looking at your video.
I am not sure what the tolerance can be but that seems like a lot.
Any experts?
 
It would seem to me a sticking or leaky exhaust valve would give higher egt due to leaking hot gas. When under power does the egt return to historical normal? If so I would not be too concerned, you may have too much data to worry over:)
 
Normal wobble. There is no Lycoming flying that doesn't do it after 200 hours. If you really clean the inside of the guide and shine a light in one end you can clearly see how they wear. All due to poor rocker arm geometry.

As long as the valve face does not show hot spots I wouldn't worry about it.
 
While things are apart, check the intake valve as well. Had a couple intake valves on a 540 that were sticking. Honed the guides and lapped the valves as it was showing signs of hot spots. Been running fine since.
 
If you really want to watch a "normal" Lycoming valve operate, get a dental camera and watch the valve close on one that has an appreciable amount of wear in the guide. Due to the side loading by the rocker arm the valve actually will slide sideways then close.
 
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