carusoam Posted December 13, 2018 Report Share Posted December 13, 2018 Most engine monitors will store years worth of data on the fastest time setting... When downloading data, capture it all on the computer... it is easy to go through the files to pick the flight that you want later.... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
Doug Schumacher Posted January 3, 2019 Author Report Share Posted January 3, 2019 Plane is in annual. Owner is installing all new spark plug wires to see if this fixes the hiccup. Non related, we are doing the valve wobble check as the engine has about 1500 hours. We will keep you posted on any results we find. Thanks again for the suggestions. Quote Link to comment Share on other sites More sharing options...
carusoam Posted January 4, 2019 Report Share Posted January 4, 2019 It kind of seems odd to be replacing things and doing work without pulling the data that is stored in the engine monitoring device... Usually, observations are made in flight... data gets down loaded, graphs get posted.... oddities appear in the graphs... People make recommendations based on experience... Fine wire plugs are a type of spark plug, and a good choice... the right part number is also important... Ignition wires are the wires that feed electricity to the plugs, from the mags. Visually inspecting them for damage can be very helpful. They will show signs of wear if they are the problem. If they are original to the plane... they are good for replacement... A lot of engine health issues can be determined by their age... like the last time the mags saw an overhaul... Are you able to read the log books? Best regards, -a- Quote Link to comment Share on other sites More sharing options...
gsxrpilot Posted January 4, 2019 Report Share Posted January 4, 2019 You all knew this was coming. Get a modern engine monitor and learn to use it. Or do things the old fashioned/expensive way and just keep changing things until you get lucky. There's just no reason to chase gremlins blindly when data is available. But you have to know how to collect it and how to read it. I fly a Mooney that is known to be a maintenance hog and go through engines prematurely. The first thing I did after the purchase of the airplane was to install an EDM900 and open a SavvyAnalysis account. Consequently my maintenance costs are no more than they were with my M20C. And I'm approaching TBO with all original cylinders working as well as they did when new. I don't know for sure, but I believe the engine monitor has probably paid for itself a few times over by now. Quote Link to comment Share on other sites More sharing options...
Yetti Posted January 4, 2019 Report Share Posted January 4, 2019 A long time ago I fixed computers for a living. There were people that were good at it, because they would diagnose the problem, then apply the correct solution. It was the fastest way and the cheapest way to fix the computer. There were techs that would try everything they had done before to fix a computer. That would take a long time and sometimes they never knew what was wrong and they might not have learned the solution to try. We are talking days vs. an hour. Since you seemed to isolate to one cylinder and is was not violent, then it would be one of the plugs on that cylinder. So mag, harness, plug. The best thing would have been to move both plugs and see if the problem moved. If not, then you would know mags or harness. If the problem did move, then you know plugs. If this don't solve it, it might be the prop governor. Quote Link to comment Share on other sites More sharing options...
Marauder Posted January 4, 2019 Report Share Posted January 4, 2019 A long time ago I fixed computers for a living. There were people that were good at it, because they would diagnose the problem, then apply the correct solution. It was the fastest way and the cheapest way to fix the computer. There were techs that would try everything they had done before to fix a computer. That would take a long time and sometimes they never knew what was wrong and they might not have learned the solution to try. We are talking days vs. an hour. Since you seemed to isolate to one cylinder and is was not violent, then it would be one of the plugs on that cylinder. So mag, harness, plug. The best thing would have been to move both plugs and see if the problem moved. If not, then you would know mags or harness. If the problem did move, then you know plugs. If this don't solve it, it might be the prop governor. We used to call those computer hacks “no good board swappers”. Unfortunately there are a lot of parallels in other industries and fields. Lots of shotgun repair or diagnosis going on and if that doesn’t work, throw it away and buy a new one.Sent from my iPad using Tapatalk Pro 2 Quote Link to comment Share on other sites More sharing options...
Michel02 Posted January 5, 2019 Report Share Posted January 5, 2019 i will go for stuck valve , if my plane do that , just in case , Michel Quote Link to comment Share on other sites More sharing options...
skykrawler Posted January 5, 2019 Report Share Posted January 5, 2019 I am curious about carusoam comment: My experience of having a strong vibration... It was loud, we new something was wrong, the vibration was tremendous, the exhaust valve was crashing into the piston on departure... it was a land now kind of moment. As seconds elapsed, our land straight ahead plan was extended to land on the next available runway... I had no engine monitor to help determine what was happening.... I'm pretty sure that Lycoming engines are non-interference engines - which is to say a valve stuck completely open will not be struck by a piston. Did you have a broken valve? Small amounts of water in fuel can cause engines to stumble and can be very intermittent. Quote Link to comment Share on other sites More sharing options...
carusoam Posted January 5, 2019 Report Share Posted January 5, 2019 Krawler, The fun part of the O360... when the valve sticks open... it leaves marks on the piston... when it bends the valve’s rod... That’s my definition of a stuck valve... Other stuck valve signs are from the valve not rotating while it still goes up and down... Keep in mind this memory is now 19 years old... but it is strong enough to remember that I don’t want to repeat that experience... best regards, -a- Quote Link to comment Share on other sites More sharing options...
Michel02 Posted January 5, 2019 Report Share Posted January 5, 2019 i thing it just start , like just not close completed , like hear little puff from idle exhaust , missing a beat , The final result will be like you said , and some time blow the head off , but could be water , but must have some in the filter , or air bubble , Quote Link to comment Share on other sites More sharing options...
skykrawler Posted January 5, 2019 Report Share Posted January 5, 2019 Here is a video of a sticking valve on a cold start (usually the result of infrequent maintenance and operating at high temps) Quote Link to comment Share on other sites More sharing options...
carusoam Posted January 5, 2019 Report Share Posted January 5, 2019 Krawler, How do you know the engine monitor is showing a stuck valve? It wasn’t showing anything on cylinder #1... even after the sound of the miss went away... As for my stuck valve experience... it came within the first 10hours of ownership and without an engine monitor... after a minimal PPI, post a two year sitting outside period... M20Cs do have some history of higher CHTs... But, Infrequent Maintenance... How often do people ream the exhaust valve guide? That’s not a typical annual maintenance step... A savvy graph of EGTs makes an interesting sawtooth pattern when valves start sticking... but that requires a graph of EGT vs Time... In this video... the engine instruments aren’t telling us very much at all... that I can discern... What type of sensor is the FF indicator using? It shows a negative number at low rpm. The needle bounces with the miss. Fuel is still delivered whether the exhaust valve is operating properly or not... hmmm...., Are we talking about a misbehaving intake valve? That would be much more rare. They don’t get nearly as hot. So they don’t typically carbonize the oil into carbon chucks in the guide... PP thoughts only, not a mechanic... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
Doug Schumacher Posted January 7, 2019 Author Report Share Posted January 7, 2019 carusoam, gsxrpilot, Yetti, Marander and others, Thanks for your feedback and yes I 100% agree with you about collect and analyze data, and then act according to the data. Part swapping is for the A&Ps or owners that don't know how to do it the right way. We reached out to you for your knowledge and experience and we thank you very much for your time helping and guiding us. This particular problem is very very subtle (very small vibration) and only happens for 1-2 seconds, so it is not acting like bad gas, valves or fuel delivery. I'm 1 of the 3 pilots that fly the M20J and I'm not the owner, so I've been sharing your comments with the other 2 guys. The owner has bought a new set of fine wires and mag capacitors that will be installed during the annual. The mags and prop were rebuilt about 100-200 hours ago. If the problem exists after the annual we will swap the plugs to see if the problem moves with the plugs. We have not downloaded the data or setup a Savvy account, but we will try to do this after the annual is complete if the problem remains. Thanks again, we are grateful to have you guys as a resource,.............I'm listening and learning. 2 Quote Link to comment Share on other sites More sharing options...
Hank Posted January 7, 2019 Report Share Posted January 7, 2019 Remember tomset the data collection rate on your engine monitor to as fast as it will go, somthat these infrequent "blips" can be recorded and reviewed. Many monitors come set for every 6 seconds, but can be set to much faster. Quote Link to comment Share on other sites More sharing options...
skykrawler Posted January 13, 2019 Report Share Posted January 13, 2019 Carusoam, I pulled that video off of YouTube - not my airplane. But there is a 'dead miss' on the engine and #1 has no CHT or EGT. So there is no compression and resulting combustion on #1 and that is reflected by the engine monitor. The valve, probably exhaust, is stuck open - never closes. Seems to eventually generate a little EGT on #1 so there must be some ignition causing some flame. As for maintenance, that's just basic maintenance: regular oil changes. My engine monitor is old enough that it does not record. But the Insight GEM pilots guide has a very good section for diagnosing engine problems based on what is displayed. ......not an expert on anything 1 Quote Link to comment Share on other sites More sharing options...
skykrawler Posted January 13, 2019 Report Share Posted January 13, 2019 Quote Link to comment Share on other sites More sharing options...
carusoam Posted January 13, 2019 Report Share Posted January 13, 2019 12 hours ago, skykrawler said: Carusoam, I pulled that video off of YouTube - not my airplane. But there is a 'dead miss' on the engine and #1 has no CHT or EGT. So there is no compression and resulting combustion on #1 and that is reflected by the engine monitor. The valve, probably exhaust, is stuck open - never closes. Seems to eventually generate a little EGT on #1 so there must be some ignition causing some flame. As for maintenance, that's just basic maintenance: regular oil changes. My engine monitor is old enough that it does not record. But the Insight GEM pilots guide has a very good section for diagnosing engine problems based on what is displayed. ......not an expert on anything Expect that when an exhaust valve is not working... (let’s say it magically left the engine....) 1) Without compression, there will be little to no ignition of fuel in that cylinder... most of the fuel will leave before the piston reaches 25° BTDC (timing of early spark ignition) 2) that fuel/air mixture still goes somewhere... down the exhaust pipe... 3) that is a lot of fuel ready to burn... it will come in contact with some hot surfaces and other burning exhausts down stream... 4) expect that fuel to burn enough to register heat on the EGT probe... or exhaust gasses circulating will keep it pretty warm.... 5) If expecting a valve to not be working (or missing)... the dental cam technology is quite amazing... every mechanic can have one from Amazon... Best regards, -a- PP thoughts only, not a mechanic... Quote Link to comment Share on other sites More sharing options...
mikefox Posted January 14, 2019 Report Share Posted January 14, 2019 A friend of mine had this in his aircraft. Very subtle vibration that would last for a second or so, and was accompanied by slightly increased EGT on one cylinder during the roughness. Turned out to be oil ring that was broken, and when the gap lined up with the other ring gaps, oil leaked into the cylinder, changing the combustion process (hence the EGT indication). Quote Link to comment Share on other sites More sharing options...
Ev Mac Posted January 23, 2021 Report Share Posted January 23, 2021 Doug, Did you ever resolve this issue? What was the final diagnosis? Seeking input as we are seeing same problem. Thank you, EM Quote Link to comment Share on other sites More sharing options...
carusoam Posted January 23, 2021 Report Share Posted January 23, 2021 Welcome aboard Ev! @Doug Schumacher hasn’t been by in a while... I sent a ping to see if he is still connected... If you want to describe what you are seeing... We can probably give some insight... Go MS! Best regards, -a- Quote Link to comment Share on other sites More sharing options...
PT20J Posted January 23, 2021 Report Share Posted January 23, 2021 Seems lIke a perennial problem: someone has a problem and asks for help. Others offer assistance by sharing their knowledge, experience or intuition. OP never closes the loop after presumably resolving the issue and thus we lose the opportunity to learn from the experience. Skip 2 Quote Link to comment Share on other sites More sharing options...
Skybrd Posted January 23, 2021 Report Share Posted January 23, 2021 Doug, I think you might something going on with the prop governor. It might be something small in the oil system. Have you tried putting some marvel mystery oil in the oil. It might clean up a restriction in the governor and also clean up deposits on valve guides. It’s a cheap fix if that’s what is causing the intermitten rpm change. I’m not sure a engine hickup would cause an rpm up flux. Good luck and happy flying. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.