Maintenance trick for a sticking valve

[Paul 5r4]

Hi everyone. I've never had a valve sticking issue but have read threads here of folks who have. Mike Bullock has an excellent thread of how to deal with the issue.
I just ran across a video on you tube that I feel is EXCELLENT. It seems pushing a valve down into the cylinder would be scary at the least... this video
turns it into a nonevent. Just a great trick so I had to share. EDIT: It says video unavailable. Just click on "watch on you tube" and it takes you there.

 

[pecanflyboy]

I've found that using .025 safety wire works better. The dental floss will break quickly, especially if it catches and edge on the valve guide. Ream the carbon and lead out of the guide with the correct reamer (MacFarlane). Also, try to clean the lead off of the stem of the valve by letting it fall through the spark plug hole. Finally, "they" say using Marvel Mystery oil will help. To prevent sticky valves, aggressively lean on the ground and in-flight to scavenge as much lead from the engine as possible.

Typically the issue is caused by lead failing to be fully scavenged from the cylinder, and solidifying on the valve guide. When a ridge of lead is formed on the stem of the guide, it will start pressing lead into the guide and the valve will stick. The lead has to be removed from the valve guide and the ridge removed from the stem.

I had a chronic issue on an O-200. Using the above techniques, MMO, and teaching the user to aggressively lean on the ground and in-flight, the problem was solved.

 

[azrv6]

Thanks for posting the link to this video, saved for future reference.

 

[Roadjunkie1]

I can't get the Utube link to work. Takes me everywhere but the cylinder video....

 

[Snowflake]

Don't click on the little YouTube icon in the corner. Click on the "Watch on YouTube" link near the middle.

 

[edhunter]

I did this yesterday on my IO-320 with 437 hours. Only the valve would not slide down the guide with the dental floss in place. The good news is that all 4 exhaust valves were slick as a whistle - no sticking whatsoever. I removed the springs (the valve wizard makes this an easy job but my tool broke in 3 places on the first cylinder, necessitating reassembly and strengthening with JB Weld putty- guessing this thing is 3D printed?? ). Once the springs were off the valve stem could easily be spun and slid in/out guide with no resistance at all. I did not measure with a dial indicator ("wobble test") but the play was minimum - just enough to detect. Putting it back together was easy enough, new cover gaskets and good to go. I've had a slight stumble on occasion and worried I might have a sticking valve.

 

[wawrzynskivp]

I used the dental floss technique and was very happy with the results. Specifically 'dental tape' rather than the lighter dental floss which is more prone to breaking. I was surprised at how hard I could pull on the dental tape. Having some kevlar yarns would be even better! I used three to four feet, a clove hitch in the middle of the floss on the valve stem keeper groove and the last essential step is to knot the bitter ends together making the whole thing a big loop. That makes retrieving the floss back through the valve guide or spark plug hole a very simply task with a hooked piece of wire. On my engine I needed the two jaw mechanic's fingers to lift the valve into alignment and having the exhaust port exposed really helped a great deal.

Reamed and lapped, resulting compression was 76/80 across the board.