Yourpilotincommand Posted January 13, 2022 Report Posted January 13, 2022 I suspect mine is not in the correct position and maybe pulling a suction drawing out excessive oil vapors from the crankcase… and on to the belly. It’s an easy check to eliminate the cause of my excessive oil consumption. Would someone kindly share a picture of their tube and a measurement? I’ll photograph mine next time I’m at the hangar. I’m hoping that’s the issue. I do have chrome cylinders which are known to have a higher blow-by than other types. I’ve been consuming about a quart very 4ish hours and would like to improve that. I am also considering a AOS. Also.. my oil filler tube is always loose at the base and seems I have to tighten it each flight.. I understand the loose filler tube could be a cause of elevated crankcase pressure. I might do the old airspeed indicator trick to check the crankcase pressures as Mike Busch mentions. Comments please! Thanks, Chris here is a great video from Mike Busch discussing crank case pressures, blow by, leaks, causes, etc…. 1 Quote
mike20papa Posted January 14, 2022 Report Posted January 14, 2022 Where the hose connects to the alumn. tube at the cowling bottom .. make sure that the hose is not covering a hole about the size of a #10 drill. 2 Quote
carusoam Posted January 14, 2022 Report Posted January 14, 2022 There is a discussion about the whistle hole and it’s location around here somewhere… including all the details about location and length… I think @GEE-BEE AEROPRODUCTS offered to make nice replacement parts for it… Doc probably supplied maintenance manual drawings… Chrome cylinders are known for not breaking in very easily… resulting in higher oil use/loss… PP thoughts only, not a mechanic… -a- Quote
Yourpilotincommand Posted January 24, 2022 Author Report Posted January 24, 2022 Any opinions on the placement of the breather tube? The red arrow in the 2nd photo notes the “whistle hole”. The blue arrow notes the position of the tube end above the bottom of the fuselage at firewall which is approximately 1 inch. Wondering if it needs to be flush. Thanks. Quote
carusoam Posted January 25, 2022 Report Posted January 25, 2022 The dimensions are there for a reason…. Mostly, it took somebody a long time to figure out why stuff didn’t work….. When it comes to vent tubes in an airstream… they want to avoid vacuums, pressurization, or stay about neutral… Simply find the dimensions, and install that way…. Expect that some tubes got replaced, and didn’t get executed properly, or something changed…. Best regards, -a- 1 Quote
Yourpilotincommand Posted January 25, 2022 Author Report Posted January 25, 2022 9 hours ago, carusoam said: The dimensions are there for a reason…. Mostly, it took somebody a long time to figure out why stuff didn’t work….. When it comes to vent tubes in an airstream… they want to avoid vacuums, pressurization, or stay about neutral… Simply find the dimensions, and install that way…. Expect that some tubes got replaced, and didn’t get executed properly, or something changed…. Best regards, -a- Thanks Carusoam. That’s my problem... I cannot find the dimensions. Quote
47U Posted January 25, 2022 Report Posted January 25, 2022 On 1/13/2022 at 1:39 PM, Yourpilotincommand said: I suspect mine is not in the correct position Found this thread on a Bing search… 2 Quote
carusoam Posted January 26, 2022 Report Posted January 26, 2022 Bob Belleville did a nice job showing where the hose is located… but, his installation was updated after that pic… (to include the whistle hole in a metal tube…. Let’s see if @M20Doc can give insight on the length of the case vent extension… (how far below the sheet metal the tube extends?) Best regards, -a- 2 Quote
jamesm Posted January 26, 2022 Report Posted January 26, 2022 I have been experimenting with mine. I want to see if increasing the length that is expose out in the slip stream will keep the oil off the belly. Quote
asaxet Posted January 26, 2022 Report Posted January 26, 2022 what level are you servicing the sump to.... On my 66e anything more than 5 quarts showing on the dip stick ends up on the belly in short order.... 1 Quote
Guest Posted January 26, 2022 Report Posted January 26, 2022 There seems to be a number of different shapes for the aluminum tube portion of the vent system. It would be best to check with tech support at Mooney to get the correct shape and size tube. Clarence Quote
Yourpilotincommand Posted January 26, 2022 Author Report Posted January 26, 2022 Thank you Carousam and 47U !!! I at least know that my breather tube is upside down (whistle hole) as well as out of position. 1 Quote
Prior owner Posted January 27, 2022 Report Posted January 27, 2022 Before I go into my experience, what oil level are you starting your consumption measurement from? Try filling oil to 5.5 - 6 qts only, put 4 hours on it, then check it the next day when it’s cold- did you really lose a full quart? If you’re starting at 7 quarts, you’re not doing yourself any favors. I too, had issues with my channel chrome cylinders… compressions were good, engine power seemed fine, my oil consumption was a little bit worse than yours, and I spent a good deal of time researching the issue, worrying about it, manipulating my vent tube placement, making a whistle hole, eventually installing an Airwolf oil/air separator, and finally, removing the separator. The fact is, you have chrome cylinders…and like many of the owners who do, you’re never going to enjoy the ridiculously low oil consumption numbers that you sometimes read in this forum. Provided you don’t have any other cylinder health issues and you aren’t exceeding the oil consumption limits In Lycoming’s manual, chrome doesn’t have to be a bad thing. For $600+ An oil/air separator will keep your belly clean and might even give you another 0.25 to 0.5 hours more per quart, but you’ll be feeding combustion byproduct acids right back into your engine- I’ve cleaned too many of these things out, and they just don’t completely separate ALL the acids and water from the oil…. A breather vent pipe accomplishes this task much better. In my limited experience, I would say, have the engine inspected and assessed properly, so that you can stop worrying about it, and feed the beast oil while you enjoy your plane for years to come… or, buy 4 new cylinders and be done with it. The maintenance history on my cylinders was poorly documented, and although my engine was only about 65 hours out of overhaul when I bought the plane, from what I could gather, the chrome cylinders had 200+ hours on them, and my borescope revealed that someone (overhaul shop?) had run a hone through all of them (which is a no-no), and they were all glazed. My oil temp was also elevated due to excessive cylinder blowby. I wasn’t going to put another hour of my time or another dollar into attempts to de-glaze & re-ring chrome cylinders that had been damaged with a hone…so I installed 4 new cylinders. My Tailpipe is now dry, my breather drips a few drops on the ground at the end of each flight, and oil consumption is much better. You might be in a different situation as far as the condition of your cylinders- a qualified A&P with a borescope should be able to properly assess your situation. Here’s one cylinder at roughly 100 hours SMOH and its intake valve (all the cylinders were in about the same condition)- obviously, I had more issues than just glazed cylinders: 1 1 Quote
N6066Q Posted December 3, 2022 Report Posted December 3, 2022 @Yourpilotincommand can you kindly take a picture of how your breather tube looks now and post? Did your adjustments have a tangible impact to oil useage? Thanks in advance. Quote
TheAv8r Posted June 8 Report Posted June 8 Reviving this thread. My '65 M20E with 165hrs SMOH has an oily nose-gear door and left-side of the belly, we suspect from the breather. The cylinder compressions are all perfect, literally 80/80 on every cylinder. The oil remains clean and doesn't darken quickly and everything looks healthy on the borescope, so seems very unlikely to be cylinder blow-by. We suspect it could be the position of the breather tube that is causing a bit of a vacuum to pull oil out. Bob's post referenced in this post no longer has pictures in it, and I cannot find anything on Mooney or Lycoming sites explaining how it should be installed. For those who tackled this in this thread - any pics, documentation? Did anyone get the exact dimensions from Mooney? Quote
takair Posted June 8 Report Posted June 8 Don’t think I have a picture today, but can you confirm you have the whistle slot hole sitting above the cowl cove exit? That should minimize the effect of any low pressure draw. Does the vent line slant up for the first few inches? Do you have a dribble of oil coming from the vent after flight? If not, the oil may be coming from elsewhere. Quote
TheAv8r Posted June 8 Report Posted June 8 56 minutes ago, takair said: Don’t think I have a picture today, but can you confirm you have the whistle slot hole sitting above the cowl cove exit? That should minimize the effect of any low pressure draw. Does the vent line slant up for the first few inches? Do you have a dribble of oil coming from the vent after flight? If not, the oil may be coming from elsewhere. The whistle hole is above the cowl exit. The vent is S-shaped, with the top part curving forward and the bottom part curving aft, it extends beyond the firewall a good few inches. Here’s a pic, ignore the zip tied hose, that’s for something else we were doing. Yes, there is a dribble of oil from the vent after flight, and the inside of the vent is wet with clean oil. Quote
47U Posted June 8 Report Posted June 8 4 hours ago, TheAv8r said: My '65 M20E with 165hrs SMOH has an oily nose-gear door and left-side of the belly, we suspect from the breather. How many quarts of oil do run in the crankcase? Quote
TheAv8r Posted June 8 Report Posted June 8 1 hour ago, 47U said: How many quarts of oil do run in the crankcase? Never more than 6. Quote
takair Posted June 8 Report Posted June 8 6 hours ago, TheAv8r said: The whistle hole is above the cowl exit. The vent is S-shaped, with the top part curving forward and the bottom part curving aft, it extends beyond the firewall a good few inches. Here’s a pic, ignore the zip tied hose, that’s for something else we were doing. Yes, there is a dribble of oil from the vent after flight, and the inside of the vent is wet with clean oil. Mine looks similar. Do you have any upslope at the exit from the case? Not that it is a fix but t might help. Quote
47U Posted Monday at 01:58 AM Report Posted Monday at 01:58 AM 4 hours ago, TheAv8r said: Never more than 6. That sounds reasonable… How many flight hours are you getting between adding a quart of oil? Has the engine been thoroughly inspected for any external leakage? Is there oil in laying in the bottom of the cowl after a period of time? Quote
TheAv8r Posted Monday at 02:59 PM Report Posted Monday at 02:59 PM 12 hours ago, 47U said: That sounds reasonable… How many flight hours are you getting between adding a quart of oil? Has the engine been thoroughly inspected for any external leakage? Is there oil in laying in the bottom of the cowl after a period of time? Around 6hrs / 1 qt. The engine is leak-free, that was the first thing we checked . I emailed Mooney and they sent the original drawing for the breather, here it is for reference. Mine is certainly the right shape, though it's hard to determine how far out into the airflow it's supposed to stick, I followed up with Mooney to ask. Quote
47U Posted Monday at 09:00 PM Report Posted Monday at 09:00 PM 5 hours ago, TheAv8r said: Around 6hrs / 1 qt. Could be better, but 6 hrs / qt is well within the expected range of oil usage. Interested to hear what Mooney says about the vertical position of the breather tube… Quote
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