Mooneymite Posted October 30, 2016 Report Posted October 30, 2016 (edited) There's nothing quite so aggravating as an oil leak. I had one on an experimental plane I own.....not my Mooney, but since it's got a Lycoming, my travails might be of general interest to Mooney owners and something to check for on your annuals. About a year ago, I began to have a small, but persistent oil leak. I looked in all the suspect places and did a thousand things none of which solved the problem. Like all oil leaks, this one did not fix itself and went from a minor irritation to a major concern. There's a picture of the post flight when I decided that the plane was grounded until fixed...the leak had gone from "progressively worse" to major issue in one flight. Grounded! The oil was coming from "all over" which made trouble shooting difficult. Even a quick run-up after a thorough bath wouldn't localize the leak to anything better than "left side forward of the accessory section". It actually looked like it was somehow coming from the starter. I did find the leak and it wasn't tough after the leak got big enough. A hole in the top of #2 cylinder rocker-arm oil return line. Because I was paying close attention to oil consumption, I can say that on that last flight, it was losing about a pint in 15 minutes. Good thing I wasn't on a long flight! Good thing I wasn't running minimal oil quantity. What caused the hole was also of interest. Even though there was nothing rubbing on any of these lines when I repeatedly checked them statically, it is now apparent that when the engine was running, the baffeling just above the line would "bow out" just a bit and make contact with the line. The baffeling edge, over time with engine/airstream vibration, sawed a nice cut into the soft aluminum. Edited October 30, 2016 by Mooneymite 3 Quote
carusoam Posted October 30, 2016 Report Posted October 30, 2016 Nice catch! If there were an area that has a lot of room to improve. The oil return lines from the cylinder heads has got to be one. And the rocker cover seals, for anyone still using cork... Best regards, -a- 3 Quote
Bob_Belville Posted October 30, 2016 Report Posted October 30, 2016 Just now, carusoam said: Nice catch! If there were an area that has a lot of room to improve. The oil return lines from the cylinder heads has got to be one. And the rocker cover seals, for anyone still using cork... Best regards, -a- Anthony, I just replaced a leaking rocker cover seal... with cork. Engine only has 160 hours since OH. What is the alternative? Quote
Mooneymite Posted October 30, 2016 Author Report Posted October 30, 2016 (edited) 9 minutes ago, Bob_Belville said: Anthony, I just replaced a leaking rocker cover seal... with cork. Engine only has 160 hours since OH. What is the alternative? http://www.aircraftspruce.com/catalog/eppages/siliconecalvecover_08-01314.php?clickkey=8111 When installed correctly, these last virtually forever and do not leak. Most people who have trouble with them, over tighten them. Not too tight, not too loose....easy does it and you're done! No drips. Edit: I originally posted the link to the experimental version....now corrected. Edited October 30, 2016 by Mooneymite 2 Quote
carusoam Posted October 30, 2016 Report Posted October 30, 2016 I really like cork for what it can do as a natural material. Wine enthusiasts are slowly coming to the realization that natural cork can lead to dissapointment as an oxygen barrier. I am a bigger fan of silicone rubber for it's consistency, toughness, and performance in high temperature applications. My O360 taught me a few lessons. It was not a well cared for engine prior to my ownership. Much of it's rubber parts and seals were 40 years old.... it's hardware was mix and match hose clamps of various sizes and styles... everything dripped, and of course, I was told (and wanted to believe) that was normal external case lubrication. All of this pales in comparison to mite's experience with a hose getting slowly cut open. It would have taken me a lot longer to recognize something going wrong because of the background oil leaks. Fortunately, the hose bits and clamps and MS knowledge are not large dollar items. Large value, but not large AMU. Best regards, -a- Quote
Guest Posted October 30, 2016 Report Posted October 30, 2016 2 hours ago, Mooneymite said: There's nothing quite so aggravating as an oil leak. I had one on an experimental plane I own.....not my Mooney, but since it's got a Lycoming, my travails might be of general interest to Mooney owners and something to check for on your annuals. About a year ago, I began to have a small, but persistent oil leak. I looked in all the suspect places and did a thousand things none of which solved the problem. Like all oil leaks, this one did not fix itself and went from a minor irritation to a major concern. There's a picture of the post flight when I decided that the plane was grounded until fixed...the leak had gone from "progressively worse" to major issue in one flight. Grounded! The oil was coming from "all over" which made trouble shooting difficult. Even a quick run-up after a thorough bath wouldn't localize the leak to anything better than "left side forward of the accessory section". It actually looked like it was somehow coming from the starter. I did find the leak and it wasn't tough after the leak got big enough. A hole in the top of #2 cylinder rocker-arm oil return line. Because I was paying close attention to oil consumption, I can say that on that last flight, it was losing about a pint in 15 minutes. Good thing I wasn't on a long flight! Good thing I wasn't running minimal oil quantity. What caused the hole was also of interest. Even though there was nothing rubbing on any of these lines when I repeatedly checked them statically, it is now apparent that when the engine was running, the baffeling just above the line would "bow out" just a bit and make contact with the line. The baffeling edge, over time with engine/airstream vibration, sawed a nice cut into the soft aluminum. It seems that Mooney knew about this problem as well. Here is the SI covering it. http://mooney.com/en/si/M20-77.pdf Clarence Quote
Mooneymite Posted October 30, 2016 Author Report Posted October 30, 2016 35 minutes ago, M20Doc said: It seems that Mooney knew about this problem as well. Here is the SI covering it. http://mooney.com/en/si/M20-77.pdf Clarence Wow! That's very interesting. Thank you for sharing this! Quote
Guest Posted October 30, 2016 Report Posted October 30, 2016 48 minutes ago, Mooneymite said: Wow! That's very interesting. Thank you for sharing this! Looks like the same location as your damaged tube. Clarence Quote
Mooneymite Posted October 30, 2016 Author Report Posted October 30, 2016 Just now, M20Doc said: Looks like the same location as your damaged tube. Clarence Zactly! Quote
mike_elliott Posted October 30, 2016 Report Posted October 30, 2016 Just now, Mooneymite said: Zactly! Had this happen to my 70 F model about 10 years ago. Was found fairly easily after cleaning up the engine real well and then using Magnaflux developer on it. Run the engine pretty hard for about 10 min and it showed me right where the leak was. That little pin hole could spray a lot of oil on things! Quote
laytonl Posted October 30, 2016 Report Posted October 30, 2016 I had the same thing on my first Mooney, a '78 J. I was difficult to find until it got really bad. Lee 1 Quote
Mooneymite Posted October 31, 2016 Author Report Posted October 31, 2016 20 minutes ago, laytonl said: I had the same thing on my first Mooney, a '78 J. I was difficult to find until it got really bad. Lee Gosh....I had no idea this was widespread. 1 Quote
carusoam Posted October 31, 2016 Report Posted October 31, 2016 1585 airframes covered by that Service instruction. If the baffling,was a Lycoming part, there have got to be quite a few more than just Mooneys. Best regards, -a- Quote
Guest Posted October 31, 2016 Report Posted October 31, 2016 The inter cylinder baffles have a Lycoming part number, the rest are provided by the airframe manucturerer. Clarence Quote
Yetti Posted November 1, 2016 Report Posted November 1, 2016 Another way to cut the return lines is the removal of the threaded rod that holds the baffles together and replacement with safety wire. Safety wire will cut aluminum tubes really quick. Return lines are something to check every time you mouse milk the exhaust. Quote
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