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Thread: Stuck Exhaust Valves

  1. #1
    Bowie's Avatar
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    Stuck Exhaust Valves

    [URL]https://vimeo.com/287329436[URL]

    Ok I don't know how to post video. I have two exhaust valves stuck open on a Lycoming O-540 J1A5D. The cylinders are Lycoming 220hrs since new, ported and polished by Lycon. The CHT's on this engine install run cool, 320 summertime 280 wintertime, have six channel EGT and CHT. I lean about 100 ROP at and bellow 75%, oil temp between 170-175, Plugs are all fine wire and clean, timing was off by quite a bit, 19 instead of 23, oil changes and oil analysis every 25 hrs, burns about 1qt per 25hrs, I fly once per week minimum about 200hrs per year total, have six channel CHT and EGT. The engine had "morning sickness" prior to 800 mile flight to the factory for annual, this was a first for me so I convinced myself I had water in the fuel, engine smoothed out after warm up and ground run and I had an uneventful flight. Two days later the mechanic started up cold engine and shut right down due to very rough run, he removed the rocker covers and found exhaust valves on cylinders 2 & 4 stuck open, moving forward with rope trick and valve guide R&R on all six cylinders. Am I doing something wrong? I would like to avoid having this happen again.
    Last edited by Bowie; 08-29-2018 at 04:52 PM.

  2. #2
    www.SkupTech.com mike mcs repair's Avatar
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    Look at top of pistons and make sure you didn’t hit piston with valve or bend valve. If a valve head breaks it will most likely smash through piston and the travel throughout engine ruining engine.


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  3. #3
    Bowie's Avatar
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    Thanks mike will do


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    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by Bowie View Post
    Thanks mike will do


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    Also, if the timing has changed you best check the points gap”e-gap”


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    FdxLou's Avatar
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    Run leaner. No more than 20 ROP. Use Lucas Upper Cylinder lubricant. Lucas Upper Cylinder Lubricant, 32.0 FL OZ, Yellow$8.87Walmart. Ream exhaust guides every 500 hrs max.

    Lou1
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  6. #6
    aktango58's Avatar
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    Quote Originally Posted by FdxLou View Post
    Run leaner. No more than 20 ROP. Use Lucas Upper Cylinder lubricant. Lucas Upper Cylinder Lubricant, 32.0 FL OZ, Yellow$8.87Walmart. Ream exhaust guides every 500 hrs max.

    Lou1
    That is really lean!! Take it to peak then rich until she runs smooth. Run MMO or TCP to decrease the carbon; Or... low compression engine mix 25% av-75% mo gas
    I don't know where you've been me lad, but I see you won first Prize!
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  7. #7
    Steve Pierce's Avatar
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    I'd push the valve into the cylinder and ream them rather than remove and replace.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

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    I would lean aggressively on the ground at startup and after landing. Also would avoid prolonged warmup.
    1. Engine is warm enough for take-off when the throttle can be opened without the engine faltering.

      DENNY




  9. #9
    Bowie's Avatar
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    Lou- I'll give leaner a try and see were my CHT land
    AKtango58- I have a low rpm higher compression lycoming and must run straight 100ll
    Steve- We are pushing valves in and reaming
    Denny-I do lean aggressively on the ground I could shorten warmup
    Thanks
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  10. #10
    Bowie's Avatar
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    Mike I've heard of e-gap but it's above my pay grade and need to find someone who speaks bendix mag. I have the bendix dual mag (one drive two mags) it's got about 220hrs on it since install. I'm assuming you can check in place but need to remove to adjust. Almost zero space between firewall and mag.

  11. #11
    skywagon8a's Avatar
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    Quote Originally Posted by Bowie View Post
    Mike I've heard of e-gap but it's above my pay grade and need to find someone who speaks bendix mag. I have the bendix dual mag (one drive two mags) it's got about 220hrs on it since install. I'm assuming you can check in place but need to remove to adjust. Almost zero space between firewall and mag.
    This is a place to start. http://enstromhelicopter.com/wp-cont...aintenance.pdf The dual mags can be a bit more troublesome if not done correctly.
    N1PA
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  12. #12
    WhiskeyMike's Avatar
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    This is what happens when the valve sticks and stays stuck. Next time it has morning sickness, leave it in bed until fixed.

    Nashvile. landing.png

  13. #13
    Bowie's Avatar
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    Thanks Skywagon.
    WiskeyMike I'll take that to heart, First and last time I'll fly when the bird's sick. It was the first time I've had that happen, I convinced myself that I had run some water through the carb and it had cleared, yes I did sump during preflight, bad call on my part.


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    FdxLou's Avatar
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    Bowie
    It also helps if you do your run up leaned like you have it set when you taxi.
    Good call on leaning aggressively while respecting no higher than 380 CHT. If anything you will have lower CHT’s when leaning greater then 50 ROP.
    On another point I get better results using Lucas upper cylinder treatment to reduce carbon buildup then I ever did with MMO. Cheaper too. Mix 3-4 oz per 10 gals of gas. Best if done on a long cross country.

    Lou

  15. #15
    www.SkupTech.com mike mcs repair's Avatar
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    also look for bent push rods after a stuck valve..... they have been known to wear/break into 2 pieces inside push rod housing then...

  16. #16
    BC12D-4-85's Avatar
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    Last time I had a Lycoming exhaust valve stick it cost me an overhaul from cam and lifter body wear. Too much surface pressure between components I assume. Do whatever satisfies to ensure that didn't happen.

    Gary

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    Can someone explain how leaning prevents a stuck valve?

    This problem has been solved years ago - run Marvel (or like-product) in the gas (and oil, if you want)...the old mechanics/aviators been using it for years to free/prevent sticky valves. I don't recall hearing them say to lean it more though.

  18. #18
    Gordon Misch's Avatar
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    Reduce carbon and lead deposits?
    Gordon

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  19. #19
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by BC12D-4-85 View Post
    Last time I had a Lycoming exhaust valve stick it cost me an overhaul from cam and lifter body wear. Too much surface pressure between components I assume. Do whatever satisfies to ensure that didn't happen.

    Gary
    My guess is, like a real cold engine without lifters pumped up, The stuck OPEN valve, allowed the cam lob to STRIKE the lifter, instead of riding it up the lobe. 2 very hard surfaces.


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  20. #20
    hotrod180's Avatar
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    Quote Originally Posted by FdxLou View Post
    …. I get better results using Lucas upper cylinder treatment to reduce carbon buildup then I ever did with MMO. Cheaper too.....
    Per your link, MMO is $15.87 per gallon.
    Lucas shows at $8.87 for 32 ounces, which is a quart- so twice the price of Marvel.

    It might be better, I never heard of it before.
    I used to use MMO when it was 2 or 3 bucks a quart at Walmart,
    but quit when the price started going up.
    I think it's about $5 a qt at the stores now.
    The airplane never seemed to notice the difference.
    FWIW I burn about 80/20% mogas /avgas mix.
    Cessna Skywagon-- accept no substitute!

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    Camguard is supposed to help. Anyone seeing morning sickness with Camguard?

  22. #22
    Bowie's Avatar
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    Quote Originally Posted by stewartb View Post
    Camguard is supposed to help. Anyone seeing morning sickness with Camguard?
    Excluding break in, I never ran without it, didn't curtail morning sickness for me.


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    Can sticky valves be caused by excessive leaning?

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    BC12D-4-85's Avatar
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    Probably should be something mainly added to fuel to reduce valve sticking, and MMO 2oz/5gal is my choice. Think about it. If it depended only on an oil additive to move it around that would mean same oil (with dispersed engine contaminants) would have to get to the sticking area between the valve guide and valve stem in sufficient quantity. And then somehow avoid cooking under heat and possibly form even more deposits. Something has to clean and not leave a big mess behind. Periodically checking valve to guide clearance and centering, and if plugging up reaming the exhaust valve guide or applying penetrating solvents like Kroil to clean helps.

    Gary

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    Gordon Misch's Avatar
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    In general, how common are sticky valve stems?

    Seems to me that if the guide/stem clearance is correct, and if the guide axis is co-axial to the valve seat, and if the valve is straight and correctly ground, all should be good.

    Am I wrong about this? If I am, what happens to cause sticky valves?
    Gordon

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  26. #26
    BC12D-4-85's Avatar
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    Exhaust valves should rotate some and not wear in one position. Grinding the rocker arm face off flush, building the arm slightly offset, or using an STC'd rotator like ECI did are some means to help (theory). There may be others. If they don't and clearances between the stem and guide increase due to wear (inevitable but slow is better), then exhaust gas can interact with lube to form coke (not cola) and slowly fill the void. When the clearances reach minimum sticking can occur. That's what I was taught 50 some years ago but newer experience might make that BS.

    I might add that a mechanic noted to me that if exhaust gas is getting past the exhaust valve guide with time it'll show as cooked oil around the valve springs, rocker arm, and inside the valve cover. Engine oil can turn black just like with excessive piston ring blowby.

    Gary
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    AKWING
    Exhaust byproducts are what cause the valve to stick, so the less fuel you dump in the less byproducts you will have. Now excess leaning can cause several other problems (high CHT, excessive valve guide wear, ect). Having a good multi cylinder CHT/EGT allows you to see what the CHT's are and adjust accordingly. 100LL contains 5 times the lead that many of the low compressions engines design called for, that is why you see problems. If you do a internet search on Camguard. You will find a good article on the chemistry involved as the lead is burned.
    DENNY
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  28. #28
    BC12D-4-85's Avatar
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    Synopsis on valve sticking: https://www.avweb.com/news/maint/182894-1.html

    Valve guide inspection and condition inspection from Lycoming - SB 388C:

    https://www.lycoming.com/sites/defau...0Condition.pdf

    Guide to why valve sticking and subsequent recommended maintenance from Lycoming - SI 1425A:

    https://www.lycoming.com/sites/defau...20Sticking.pdf

    There may be better and more current revisions but this is a start.

    Gary
    Last edited by BC12D-4-85; 09-01-2018 at 02:21 AM.
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    Quote Originally Posted by Bowie View Post
    [URL]https://vimeo.com/287329436[URL]

    Ok I don't know how to post video. I have two exhaust valves stuck open on a Lycoming O-540 J1A5D. The cylinders are Lycoming 220hrs since new, ported and polished by Lycon. The CHT's on this engine install run cool, 320 summertime 280 wintertime, have six channel EGT and CHT. I lean about 100 ROP at and bellow 75%, oil temp between 170-175, Plugs are all fine wire and clean, timing was off by quite a bit, 19 instead of 23, oil changes and oil analysis every 25 hrs, burns about 1qt per 25hrs, I fly once per week minimum about 200hrs per year total, have six channel CHT and EGT. The engine had "morning sickness" prior to 800 mile flight to the factory for annual, this was a first for me so I convinced myself I had water in the fuel, engine smoothed out after warm up and ground run and I had an uneventful flight. Two days later the mechanic started up cold engine and shut right down due to very rough run, he removed the rocker covers and found exhaust valves on cylinders 2 & 4 stuck open, moving forward with rope trick and valve guide R&R on all six cylinders. Am I doing something wrong? I would like to avoid having this happen again.
    I'm thinking you ran it like you should, and they set the valve guides up too tight.

  30. #30
    BC12D-4-85's Avatar
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    he cylinders are Lycoming 220hrs since new, ported and polished by Lycon.

    Ask why the problems and how the remedy.

    Gary
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    Colorguns's Avatar
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    What oil are you running? SO many thoughts on what oil to run! I was running Phillips x20-50 had 2 valves that were giving blow by on the valve stem, not stuck but blow by. TT 930 hrs Lyc 0-360

    Are you running Aeroshell 100W Plus? as recommended by Lycoming?

    Just wondering is all?

    Doug

    Doug
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  32. #32
    Bowie's Avatar
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    I use Phillips XC20W50 and camguard I ran my last plane with lycoming O360 1600hrs with the same stuff and operated the same way never stuck a valve So who knows maybe the valve guides were set up too tight


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  33. #33
    okmike's Avatar
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    Back in the race car days we knurled the valve guides and they held oil in the knurls thus they always had plenty of lube, we would run 225+# of spring pressure which caused problems, knurling solved the problem.
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  34. #34
    windy's Avatar
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    Stuck Exhaust Valves

    Quote Originally Posted by stewartb View Post
    Camguard is supposed to help. Anyone seeing morning sickness with Camguard?
    I ran Camguard with Phillips 20-50X/C for 1800 hrs in my engine until repeated stuck exhaust valves made me remove the cylinders to get them new valve guides & exhaust valves. I did the rope trick & reamed the guides to prolong operation before having to remove the cylinders.


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  35. #35
    Bowie's Avatar
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    Stuck Exhaust Valves

    Aerotech Engines out of Nova Scotia were at the Greenville Fly In, they told me that I'm operating properly, they also said they're getting low time lycomings with stuck exhaust valves coming to thier shop on a regular basis, as low as 80 hrs. Aerotech suggested to ream the guides slightly oversize, take out a little metal not just the coke, claim no sticking to TBO once done.


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    Quote Originally Posted by okmike View Post
    Back in the race car days we knurled the valve guides and they held oil in the knurls thus they always had plenty of lube, we would run 225+# of spring pressure which caused problems, knurling solved the problem.
    I have wondered why aircraft valve guides don't get knurled. I see knurling as an old technology to extend valve guide usefulness. I suppose it might affect the heat transfer from the valve stem to the guide to the cylinder head and overheat the exhaust valves.
    You can't get there from here. You have to go over yonder and start from there.

  37. #37
    skywagon8a's Avatar
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    Quote Originally Posted by N86250 View Post
    I have wondered why aircraft valve guides don't get knurled. I see knurling as an old technology to extend valve guide usefulness. I suppose it might affect the heat transfer from the valve stem to the guide to the cylinder head and overheat the exhaust valves.
    Perhaps it is related to low rpm running engines? An aircraft engine red line of 2700 rpm is a fast idle for most other engines.
    N1PA

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    What are you calling high compression over 8.7?

  39. #39
    Bowie's Avatar
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    Quote Originally Posted by julios View Post
    What are you calling high compression over 8.7?
    I didn't call it high compression, I'm calling it higher compression.Maules are available with a few variations of the 540. The J1A5D is rated 235hp at 2400rpm with a compression ratio of 8.5:1 The B model is rated 235hp at 2575rpm and the compression ratio is 7.2:1. The B model has an auto fuel STC available the J model doesn't, the J model weighs less than the B.


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    knurled guides were out fast. last time I tried to get that done on a vintage motorcycle (about 30 years ago) the machine shop refused to do it. plus its not an approved procedure on aircraft engines

    you only get combustion byproducts in the guide/stem if the valve leaks. how are the compression tests?

    I think the put the guide to stem clearance too tight (as already mentioned). I have fixed a couple with the 'ol rope trick. they were stuck because the clearance got big (and out of round) & oil baked in the guide. read the SB.... they let you ream the hole out way big. and there is a wobble test discussed too.

    plus 1 for checking the pushrods. they will bend. I would also check the dry tappet clearance
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