Sticking Exhaust Valve - Diagnosis and Fix!

[bullojm1]

Originally Posted by springer

Mike, I have the same engine. I may have missed it but how many hours on the engine?

One of the best write ups I have seen on VAF.

Jim,

Thanks for the compliment! I felt obliged to give a thorough write-up since details on this common issue/fix seemed to be lacking in the inter-webs. 320 hours total on the new Superior IO-360 engine.

[Chkaharyer99]

Mike,

That was a great step by step write up. I learned much by reading it and even feel almost capable of doing the surgery should the need present itself. I hope it never does.

Thank you!

[Mike S]

Mike, super writeup, very well done.

I am moving this thread to the "ongoing maintenance" forum so others can find it easier in the future.

[az_gila]

Originally Posted by BobTurner

Glad it's fixed.
As you now know certain certified Lycoming engines have a SB or AD mandating a "valve wobble test" every so many hours. Might be a good idea to get a hold of those instructions, they give more guidance than "the other 3 felt okay".

.....

Bob

It's not "certain" engines, it's ALL Lycoming engines.

It is SB333C (aka Wobble Test) and is on-line -

http://www.lycoming.com/Portals/0/te...0Condition.pdf

Helicopter Engines – 300 hour intervals or earlier if valve sticking suspected.
All Other Engines – 400 hour intervals or earlier if valve sticking suspected until exhaust valve guides are replaced with guides made of improved material. (Refer to latest revision of Service Instruction No. 1485.)


The SI 1485 describes the hi-silicon valve guides and extends the inspection to 1000 hrs.

http://www.lycoming.com/Portals/0/te...0Procedure.pdf

How to perform the "Lycoming Rope Trick" is described here, and it even tells you that it needs about 8 feet of 3/8 nylon rope -

http://www.lycoming.com/Portals/0/te...20Sticking.pdf


Even with all of the above and the new guides, my Tiger's O-360 had loose valve guides (too much wobble) at 600 hrs on brand new Lycoming cylinders.

[LettersFromFlyoverCountry]

For those of us not particularly good at making tools, can we assemble a list and source of required tools for this task?

[bullojm1]

Originally Posted by LettersFromFlyoverCountry

For those of us not particularly good at making tools, can we assemble a list and source of required tools for this task?

Bob,

My research revealed the following valve spring compressors:

This is from Aircraft Spruce - p/n 12-21520 for $60


And another option from ACS, p/n 12-00202 for $77.


SkyGeek sells this variety for $150, p/n ATS3602


And then there is the Valve Wizard for $150. This is a really nice took as it gives you both hands free to remove the keys.



Other tools include:
1) Telescoping Magnet. Make sure to get one small enough to make it down the valve guide (1/2" diameter). The stronger the magnet, the better!
2) Mechanical Pickup (I highly suggest the lighted General Tools p/n 70396 - $8 at Lowes)
3) Pick set - the cheap one from Harbor Freight worked great for me
4) Patience!

[cajunwings]

Backing up to the photo in post #3 showing the red silicone protecting the oil drain back tube. The threaded rod that clamps the front and rear baffles together goes above the oil drain back tubes not below.


Don B

RV 9 Rebuild in Prohress

[BillL]

Mike, why #2 and not others? Were your CHT's higher for #2? Any other indication of temps being higher? I just wonder how much lower temps should be to reduce the carboning of the stems.

Also - what oil brand/grade are you using?

Nice write-up (as usual for you).

[brad walton]

Curious weather you have ever done a GAMI type check to see which cylinder reaches max EGT first, 2nd, 3rd, and 4th. I wonder if this cylinder is running the richest?
Great write up, Mike!

[kinger]

Mike,

I jumping on as well..... Fantastic wright up.....

Thank You

King