Sticking Exhaust Valve, Aerosport Power Kudo's

JonJay · #1 09-28-2011, 09:07 AM

My Aerosport Power IO-360 #2 Millenium Cylinder developed a sticky exhaust valve at a little over 400 hours. It was a very subtle problem to diagnose but that is another story.
I have never removed a cylinder but found removal and reinstallation to be very straight forward. It took very little time. Off it went to Bart at Aerosport Power for a full check up.
Bart reamed the guide, honed the cylinder, replaced the rings, lapped both seats, and returned the cylinder to me in less than a week. It was returned with a package of new gaskets for exhaust, intake, valve cover, push rod tube o-rings and seals, exhaust flange nuts and washers, cylinder base o-ring, etc....
total charge = freight back to me, $26.
That is over and above any expectations I would have for an engine with 400 plus hours.
Aerosport Power is a class act.

I am taking this opportunity to redo my intake ramps and front baffle seals as I have never been happy with the fit, so, while they are off, I will redo them and hope to capture some more cooling air in the plenum.

B Cunningham · #2 09-28-2011, 02:17 PM

Quote:

Originally Posted by JonJay

It was a very subtle problem to diagnose but that is another story.

Please share the story. Im curious what your symptoms were...

JonJay · #3 09-29-2011, 09:50 AM

Quote:

Originally Posted by B Cunningham

Please share the story. Im curious what your symptoms were...

First sign of a problem was at last years annual. #2 did not come up on compression, diagnosed exhaust valve, staked it and it came back up to normal. Assumed carbon under valve, moved on.
This years annual, same...thought it unusual, but when staked it came back up just fine. That was in May.
I started noticing idle roughness for the first time. I tried to set idle mixture and idle speed but could not get consistent results. I also noticed at low RPM's the EGT on #2 was 100-150degf. below other cylinders. They have always been relatively close to each other until then.
I decided it was time to pull the jug and have a look.

Through the course of all of this the engine ran fine and showed no other symptoms at cruise or full power. The sypmtoms only showed at idle or near idle. I believe the valve had been sticking for quite some time until the symptoms finally worsened to the point of concern.

Bob Martin · #4 09-29-2011, 10:11 AM

Jon,
Thanks for the great info on your sticking valves.
How about the other 3 ?
Have you checked them for deposits or just assumed since you haven't seen the symptoms they are ok?
They all live in the same enviroment, sort of, so wondering why one would stick and not the others.

I ask this because we own a CUB with an 65hp engine and we had morning sickness a couple months ago on one cylinder. But when we checked things out, the other 3 were right behind the first one but had not gotten to sticking yet. We attributed it to the previous owner using car gas. We use 100LL with TCP. and have only put 100 hours on it, in the first year of ownership. Our fix was to remove-clean up valve stems and guides, lap the valve seats and reassemble, all the parts were still in spec. So we will be keeping an eye on it in the future. Thanks in advance for your thoughts.

JonJay · #5 09-29-2011, 10:52 AM

Quote:

Originally Posted by Bob Martin

Jon,
Thanks for the great info on your sticking valves.
How about the other 3 ?
Have you checked them for deposits or just assumed since you haven't seen the symptoms they are ok?
They all live in the same enviroment, sort of, so wondering why one would stick and not the others.

I ask this because we own a CUB with an 65hp engine and we had morning sickness a couple months ago on one cylinder. But when we checked things out, the other 3 were right behind the first one but had not gotten to sticking yet. We attributed it to the previous owner using car gas. We use 100LL with TCP. and have only put 100 hours on it, in the first year of ownership. Our fix was to remove-clean up valve stems and guides, lap the valve seats and reassemble, all the parts were still in spec. So we will be keeping an eye on it in the future. Thanks in advance for your thoughts.

Bart told me that there was some carbon in the guide on #2.
I would be open to advice on how to check the other exhaust valve guides short of pulling the jugs. I have heard of the rope trick, but then what? How would you know what was sticky and what was normal? I did pull the rocker cover on #4 and there was no comparable difference in appearance from the outside.
I did notice when I pulled #2 discoloration or inconsistancy of color and deposits around the exhause valve seat. I could scope the other cylinders and see if that existed on other cylinders, but all other cylinders are performing well so I have no reason to believe that I would see anything telling.
The symptoms have been on and off for several months. I think if others had a problem, one or the other would have started showing something. I will keep my eye on them.
Thanks.

jchang10 · #6 09-29-2011, 11:33 AM

http://www.eaavideo.org/video.aspx?v=991490765001
I would recommend watching this video from mike busch. i found it very enlightening, esp. related to diagnosing the deposits coloring on the valve itself.

Quote:

Originally Posted by JonJay

I would be open to advice on how to check the other exhaust valve guides short of pulling the jugs. I have heard of the rope trick, but then what? How would you know what was sticky and what was normal? I did pull the rocker cover on #4 and there was no comparable difference in appearance from the outside.
I did notice when I pulled #2 discoloration or inconsistancy of color and deposits around the exhause valve seat. I could scope the other cylinders and see if that existed on other cylinders, but all other cylinders are performing well so I have no reason to believe that I would see anything telling.
The symptoms have been on and off for several months. I think if others had a problem, one or the other would have started showing something. I will keep my eye on them.
Thanks.

JonJay · #7 09-29-2011, 11:42 AM

Quote:

Originally Posted by jchang10

http://www.eaavideo.org/video.aspx?v=991490765001
I would recommend watching this video from mike busch. i found it very enlightening, esp. related to diagnosing the deposits coloring on the valve itself.

Well, thanks, but unless you can guide me to the correct segment in the video, I simply don't have two hours to burn on this right now.