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Thread: Oil analysis and sticking exhaust valve?

  1. #41
    G44's Avatar
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    Quote Originally Posted by mam90 View Post
    Everything the same Gary, except probably slightly more 100LL post overhaul due to the Alaska trip. Harder to find mogas enroute. Trusted engine shop said he suspected improperly ground seats. He said he never installs new cylinders anymore without checking as he’s seen way to many. If I have any more problems I’ll pull the cylinders and take them to him.
    Mark,

    Do you run TCP? Auto fuel?

    Kurt

  2. #42
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    Quote Originally Posted by bcone1381 View Post
    I know there are folks who are not a fan of Mike Busch on this forum. The dude admits he is more of a data analyst. Points of random data exists. If we can organize the data, then we have information. If we read the information, we can gain knowledge and which leads to wisdom....or maybe leads to improved reliability of Lycoming engines. It seems to me like Engine Data analysis is Mikes strong suite. The facts below are his, not mine. Below is a synopsis of the data Mike shares in that video link in post 28 and this AOPA article
    https://www.aopa.org/news-and-media/...intance-valves

    -Cool running engines have more sticky valves than warmer running engines.

    -Valves stick due to buildup of deposits on the valve stem inside of the valve guide.

    -Laboratory chemical analysis by a petrochemist from Exxon has been performed on valve stems.

    -TEL is used as an octane booster in 100LL fuel requires a scavenging agent.

    -This lead scavenging agent that is added to help avoid fouled spark plugs.

    -A chemical reaction during the combustion event produces a byproduct of the scavenging agent called Lead OxiBromide.

    -The Lab analysis showed that Lead OxiBromide is primarily the source of the buildup on the stems of stuck valves.

    -Engine Monitor will show a rough running engine from a sticking valve to produce an EGT value that is not normal. As the engine warms and the stuck valve loosens, the EGT will indicate normal.

    -Lead Oxibromide that remains as a gas above temps of 1100F.

    -After the combustion event we want the Lead OxiBromide to remain gaseous (above 1100F) to pass harmlessly out the exhaust.

    -The hotter the temp, the faster the lead is scavenged.

    -A cooler surface will condense these gases and over time form hard deposits on surfaces they contact, like a valve stem of an open exhaust valve.

    -Sodium filled Lycoming valve stems run cooler than Continental valves and the chances of a stuck valve is more likely with them.

    --Mike thinks that the conventional wisdom that the carbon deposits on the valve stem inside the valve guide from oil contacting the hot stem and carbonizing the oil is wrong.

    What Mike says to do....

    -Since CHT is the best indicator for Valve stem temperature, keep the CHT's between 350F - 400F to avoid Lead Bromide buildup on your valve stems.

    -Lean aggressively on the ground and low power operations to keep combustion temps as high as possible.

    Attachment 52176

    Thanks for that info. Did he comment on TCP and if it was good or bad concerning valve sticking?

    Kurt

  3. #43
    nightflyer's Avatar
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    Quote Originally Posted by G44 View Post
    Thanks for that info. Did he comment on TCP and if it was good or bad concerning valve sticking?

    Kurt
    According to this article TCP does nothing for sticky valves.
    Attached Files Attached Files
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  4. #44

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    Quote Originally Posted by G44 View Post
    Mark,

    Do you run TCP? Auto fuel?

    Kurt
    I run both auto and 100LL, depending on what I can get. I’ve never run any fuel additives, but now I am using mmo.
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  5. #45
    BC12D-4-85's Avatar
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    The chemistry tutorial above is courtesy of CamGuard. Note the short time (as little as 15-20 hrs) they suggest additives become depleted and the nastiness begins. If so, why fly 50 hrs on an oil....unless you use their product?

    Gary

  6. #46

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    Through the years one of the aviation writer voices I've trusted is Ben Visser. He continues to advocate the use of leaded fuel in aircraft engines but continues to use 25% leaded to unleaded as a blend recommendation for breaking an engine in and occasional addition of leaded fuel throughout the engine's life. His reasoning centers around valve recession and valve heat transfer. In my own airplane ownership history valve recession and erosion has occurred in my engines. Valve sticking has not.

    I see evidence of accumulated exhaust crud on my shocks and remove it regularly. I assume lead is a big component of this crud. I plan to blend in some unleaded fuel to see if I recognize a reduction in the exhaust deposits. I don't have the knowledge or tools to do any important testing to find my perfect fuel so I'll err to the lead-rich side with my 10:1 cylinders. I'm not focused on valve sticking. I want the best fuel for the entire engine.
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  7. #47

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    Quote Originally Posted by mam90 View Post
    I run both auto and 100LL, depending on what I can get. I’ve never run any fuel additives, but now I am using mmo.
    If valve sticking is the problem a little MMO in the oil may be useful. I've been told that's where it got it's start with airplanes. Subsequently an engine build shop owner told me a little MMO in the oil is the first thing a pilot should do for suspected morning sickness. It may not be a long term solution but it should buy time.

    I routinely added MMO into my bulk fuel tank until talking to Mr Camguard about airplane engines and additives. He told me (this was over 10 years ago) that the MMO formula changed somewhere around 2000 and now contains a chlorinated something something and that was bad news for rubber and synthetic rubber. He didn't give its use much merit and said now it could actually do more harm than good. Since my 180 has bladder tanks I took his comments to heart and stopped using MMO. I can't recognize any difference in my engines.

    MMO is primarily a mixture of mineral spirits (Stoddard solvent) and light oil with some other magic smells and colors added. In the lead scavenging discussion which of those components is providing the benefit? Mr Camguard suggested that if I believed MMO was helpful I could mix my own and leave out the bad stuff. FWIW Seafoam fuel treatment is a similar mineral spirits/oil product with isopropyl added. Anyone using that?
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  8. #48

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    I do run camguard. I used to read the threads about sticking valves and additives and be thankful I didn’t have to deal with that. Then, overhaul with all new parts including cylinders and here I am. Hard to accept that I ran for so long with zero issues, have changed nothing in how I operate and now seeing these problems. I’ll have to look into the MMO issue, thanks.

  9. #49

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    Great discussion! I thought, (maybe incorrectly) that engine start wasn’t recommended under 40*f if you were running straight 100w. Wrong? I run the Phillips 20/50 w/Camgaurd and I use MMO in the gas and fly about 200hrs/yr. I did develop low comp on one cyl last year (50/80) from a leaking exhaust valve. The valve guide was replaced now all 4 are running 78/80 but don’t believe that had anything to do with the oil. What about engine start at temps below 40*f?
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  10. #50

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    Quote Originally Posted by mam90 View Post
    I do run camguard. I used to read the threads about sticking valves and additives and be thankful I didn’t have to deal with that. Then, overhaul with all new parts including cylinders and here I am. Hard to accept that I ran for so long with zero issues, have changed nothing in how I operate and now seeing these problems. I’ll have to look into the MMO issue, thanks.
    Is it at all possible that these new cylinders are running cooler than the TCM cylinders? Better Baffling? Do you have an engine monitor?
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  11. #51

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    Yes, that’s one of our thoughts. We built new cowling and all new baffling when we hung the engine. No engine monitor but we are going to try and rig something up to check temps. Thanks for the input..

  12. #52
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    Quote Originally Posted by Mauleguy View Post
    My two cents. I did a top overhaul on my engine and used the Phillips 20-50XC as recommended for break in by the cylinder company. The good thing about this is you can just keep running the Phillips after break in. At around 250 hours on the cylinders on a trip to Alaska I had a sticking valve out of Dease Lake. That will get your attention real quick! I came back and landed and looked things over but did not know what was going on since I had never experienced this before. I could not duplicate it and continued on. I got to Ultima Thule Lodge and had it happen again one morning. I told Paul about it and he said it sounds like a valve sticking and asked what engine oil I was using. He told me he only runs straight weight Aeroshell and told me to change oil. I continued fighting this sticking valve for another 100 hours thinking how could it be the oil and I had a few cases of oil to use. It seemed if I did a long through warm up I did not usually have a problem, then one day coming through the gorge on top and it started doing it after a flight back from Idaho and I decided this has got to be fixed. I switched oil to Aeroshell 100 plus and it never did it again. I will never use Phillips again.
    Ok in the interest of completely muddying the water on what I wrote a few days back (see above). I was talking to Loni Habersetzer today about engine oil, he flies for Paul Claus and his engines go to TBO and beyond. I was telling him my experience with Phillips and what Paul had told me about just using straight weight Aeroshell. He fired back that Ultima Thule Airplanes all run Phillips 20-50XC now and have for at least 6-7 years since Paul asked him (Loni) what engine oil he uses because he had no problems ever making TBO. I asked Loni if he has ever had a stuck valve he said no. I will continue with my use of straight weights but here is evidence that maybe just believing in something can make it better
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  13. #53
    BC12D-4-85's Avatar
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    Frequent flyers can use any oil. It's the unfrequent flyers that need some help.

    Gary
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  14. #54
    Mauleguy's Avatar
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    Ok, is not flying the airplane 6 months a year as Ultima Thule does (when there season is over) consider as frequent or infrequently. They fly 6 months daily and then not at all for 6 months, airplanes are hangard.

  15. #55
    BC12D-4-85's Avatar
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    Are the hangars heated in the off season? Edit: If they are heated above freezing find out what steps they take to reduce or prevent corrosion when sitting idle. Might be worth knowing.

    Gary
    Last edited by BC12D-4-85; 11-08-2020 at 08:40 PM.
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  16. #56

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    If you read all the posts it is a total crapshoot on what seems to work and what does not. Flying daily/weekly does seem to help for lifter/cam issues. Valve sticking is all over the board. I think one of the issues is what lean, hot, often to one person is not the same to another. Bottom line is when you notice a change even for a few seconds look into it. I do like all the information that people post because it actually has some science behind it!!
    DENNY
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  17. #57
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    From what I've seen here and in other Forums, periodic borescoping and valve cover removal (with pics recorded over time) might help show a trend in valve condition and the buildup of visible deposits. I'm not an expert in either. I do know it's a good idea to have uniform valve to seat contact to dissipate valve heat, and valve to guide inspection (visual/wobble test) can detect deposits. Some of the valve stem blow-by deposits can coat the exposed valve and springs plus the inside of the adjacent valve cover. If it becomes apparent then maybe there's a problem to be addressed. We try to keep the costs down and add a prevention step but maybe this would be worth doing?

    Gary

    Edit: I found this lengthy video on using a borescope in an aircraft application: https://www.youtube.com/watch?v=Dk5o4__0y-4 Guess i'll learn something tomorrow.
    Last edited by BC12D-4-85; 11-08-2020 at 10:59 PM.
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