N201MKTurbo Posted March 22, 2015 Report Posted March 22, 2015 Once upon a time in my F I took off with the mixture leaned and forgot to push it in. I melted all my pistons. The piston pin holes got elongated by about 10 thou and all of the ring lands became sloped so they didn't seal. It ran like you described. I had to fly 6 hours home after it happened. The engine ran fine, it just used a lot of oil. Eventually had to replace all four pistons. Quote
garysuperpilot Posted March 22, 2015 Author Report Posted March 22, 2015 was the oil blowing out the tube like mine? Hope I don't have to change them all . That would hurt. 1 Quote
Wesley brown Posted March 22, 2015 Report Posted March 22, 2015 Once upon a time in my F I took off with the mixture leaned and forgot to push it in. I melted all my pistons. The piston pin holes got elongated by about 10 thou and all of the ring lands became sloped so they didn't seal. It ran like you described. I had to fly 6 hours home after it happened. The engine ran fine, it just used a lot of oil. Eventually had to replace all four pistons. Ouch I'm sorry that happened! Quote
stevesm20b Posted March 22, 2015 Report Posted March 22, 2015 Had a similar problem. Used a quart in 2 hours and had a lot of oil coming out the breather tube. Pulled lower plugs, found # 3 cyl plug oily. Did a leak down test. All cylinders including #3 were mid to high 70s. Found #3 cyl had a broken oil ring. Was not that expensive to fix. Pulled the cylinder, had it honed and new rings. Problem solved. Quote
RobertGary1 Posted March 22, 2015 Report Posted March 22, 2015 There should be a hole on your breather tube. Chech that! Ouch I'm sorry that happened! That helps prevent icing over of the tube in IMC but won't prevent oil burning. -Robert Quote
aaronk25 Posted March 22, 2015 Report Posted March 22, 2015 Anybody ask how many quarts your taking off with? By chance is it 8-8.5, or 7.5qts? The rest of you know where I'm going with this.... 2 Quote
garysuperpilot Posted March 22, 2015 Author Report Posted March 22, 2015 So I went to the airport and pulled the plugs. No oil . They looked good. So I'll take it to my mechanic and hopefully we'll find the problem. Thanks again for all the advice. I'll let you know tomorrow whats going on. Any input is still appreciated. Quote
bonal Posted March 22, 2015 Report Posted March 22, 2015 We're there any signs of oil on or around the engine. Seems like with a fresh OH things should be very clean and an oil leak would show itself. If it's comming from the blow by you may be running with too much oil in the case. Keep us informed finding the cause could be very helpful to others. Quote
garysuperpilot Posted March 22, 2015 Author Report Posted March 22, 2015 Yes , the engine is "wet" from some oil leaking somewhere but can't pinpoint an exact location without cleaning up the engine tomorrow. It's been like that since about 50smoh but was not too concerned till now. I only run 6 quarts so there is not too much in the case. Oil seems to get dark after only 5 or 6 hours now which I know is not normal. Guess it could still be a ring problem but I'll be waiting at the mechanics hanger door at 8am. Sometimes not knowing is the hard part. It really is great just having fellow Mooney owners to share things with when there is a problem. Thank you everyone. Quote
RobertGary1 Posted March 22, 2015 Report Posted March 22, 2015 The oil leak could be secondary that only is getting noticed as a result of the report of white smoke/rough idle. Sometimes oil leaks can be hard to find when oil is everywhere. You'd need to clean it up and watch it. Feel for oil behind the prop hub and around the rocker covers. Rocker covers are a common source and easy to fix. The push tubes as well. By I wouldn't let that distract me from the indications you may also be burning. Having to run a 100 hour engine at 6 quarts indicates unusual blowby. A newer engine like that should run fine close to 8. -Robert Quote
carusoam Posted March 23, 2015 Report Posted March 23, 2015 If the oil has changed color... (Wipe the oil from the dipstick on a white paper towel) Give it a sniff, as well... Expect a piston ring to not to be doing it's job. Exhaust getting past the rings going into the oil will change the color and the smell of the oil while pressurizing the case, leading to oil being blown overboard... This is typical of really old cylinders. I haven't had new cylinders behave this way... Best regard, -a- Quote
aaronk25 Posted March 23, 2015 Report Posted March 23, 2015 One of the culprits of "really old cylinders" is most likely during their life they sat idle at some point, maybe under a previous owners watch. When this happens the shinny steel barrels rust and pit the surface, which accelerates piston ring wear, the come blow by and oil usage. This happened to me. Took 400 hours to wear the rings out of it. Sent from my iPad using Tapatalk Quote
Shadrach Posted March 23, 2015 Report Posted March 23, 2015 After thoroughly cleaning it up, look very carefully at the lower parting flange (where the case halves meet). If the case is fretting (case halves rubbing against one another), that will cause leak at the flage. Also look very carefully for case cracks. Ours had this happen years ago and it made a hell of a mess. It did not show up on the dipstick as major oil loss, but the engine was "wet" and smoked at shutdown. Our crack started at one of the passenger side lower case bolt bosses and propagated up and forward toward cylinder #1. Quote
ryoder Posted March 23, 2015 Report Posted March 23, 2015 Once upon a time in my F I took off with the mixture leaned and forgot to push it in. I melted all my pistons. The piston pin holes got elongated by about 10 thou and all of the ring lands became sloped so they didn't seal. It ran like you described. I had to fly 6 hours home after it happened. The engine ran fine, it just used a lot of oil. Eventually had to replace all four pistons. I don't think this is possible with a C due to the carbs unequal fuel distribution. It would run so rough that the pilot would observe the lean condition on going to full throttle. Quote
Shadrach Posted March 23, 2015 Report Posted March 23, 2015 The OP's plane is a 1966 M20F, but you're right on a C model you may only melt one or two pistons. It shouldn't happen in any airplane if you lean agreesively on the ground. 1 Quote
RobertGary1 Posted March 23, 2015 Report Posted March 23, 2015 If you lean it on the ground to the point that adding throttle doesn't increase rpm you can forestall that issue as well. -Robert 1 Quote
ryoder Posted March 23, 2015 Report Posted March 23, 2015 If you lean it on the ground to the point that adding throttle doesn't increase rpm you can forestall that issue as well. -Robert That's what I meant. I can't even climb up the hill to my hangar without enriching or even do the 1700 rpm run up check. Quote
Steve65E-NC Posted March 23, 2015 Report Posted March 23, 2015 105 smoh??? Why are you talking to us? You should be talking to the rebuilder. If they will not help you with this low time problem, let us have their name. Quote
garysuperpilot Posted March 23, 2015 Author Report Posted March 23, 2015 Well I brought the plane to my mechanic this morning. Engine running rough and blowing smoke and some oil out of the breather tube. Compressions all checked good and no oil on any plugs. Looked in the cylinders with the camera and could not determine which cylinder was the problem but it seemed apparent we had a ring or cylinder issue. By the time I took everything apart we agreed it was prudent to pull all the cylinders to see what was going on. Got to the number 4 cylinder and the rings were "frozen" in the piston. I had apparently "cooked" the piston. I don't know for sure how I overheated that cylinder but it was clear it was the problem. May get an engine monitor of some type at the annual coming up in may. Being my mechanic lets me do most of the grunt work it shouldn't cost too much. All the other cylinders and rings looked great. I agree it should not happen to a low time engine and I guess I just have to take the blame. Feeling relieved to have found the problem. By the way I live in North Carolina and the shop that did the overhaul is located in Florida and was done by the previous owner. I trust my mechanic more anyway but he did say everything else seemed to be done properly. Thank you all for your ideas and help. Quote
Shadrach Posted March 23, 2015 Report Posted March 23, 2015 Can you take a picture of the inside of offending cylinder as well as the top and bottom of the piston and rings? I would like to see what a "cooked" cylinder looks like on a 150hr engine. Did anyone check the injector to ensure it was flowing normally? I'm not saying that you did not cook it, but #4 is typically one of the coolest cylinders on an F Model. I struggle to get #1 and #4 above 300df this time of year in Jan and Feb, I just accept 275 to 290 in cruise. Is the underside of the piston brownish (oil varnish) compared to the others? Quote
garysuperpilot Posted March 23, 2015 Author Report Posted March 23, 2015 I meant to take a picture before I left the shop today but I didn't. I can't go by again till Thursday but I'll take a picture when I go. The cylinder looked fine but the piston was another story. It looked "dark varnished brown" on the bottom and just that "varnished color on the outside. I don't know why that was the cylinder to get hot but all the others appeared normal. Didn't check fuel flow since last annual. Sounds like a good idea to check when the engine gets put back together. Quote
RobertGary1 Posted March 23, 2015 Report Posted March 23, 2015 Does he think that cylinder was running lean for some reason? Some type of flow balance issue? -Robert Quote
Steve65E-NC Posted March 23, 2015 Report Posted March 23, 2015 For a few months after a tank reseal I had a problem with several events of partial injector blockage. Luckily I had a JPI all cylinder monitor installed and was able to back off from sky-rocketing cylinder temps. Now I have a little injector flush kit with my onboard tool set (wrenches, solvent). As usual, being prepared seemed to end the problem as it has not occurred since. At takeoff power with a partially blocked injector, temperature went way up and I had audible engine distress. I immediately backed off the throttle to reduce temps and returned for landing. It was at a Wings event, I think the volunteer check pilot wet his pants. After injector solvent cleaning I flew home with no problem. Quote
garysuperpilot Posted March 24, 2015 Author Report Posted March 24, 2015 Unsure as to the cause. Fuel issue at that cylinder is a good a guess as any because all the others were good. All I have is the single probe on the cylinder head(it was not on that cylinder ) and the standard egt gauge. May is the annual and I have already discussed it with my mechanic. I should have listened to him when he suggested I install one when I bought the plane. Is JPI what everybodys using? Quote
RobertGary1 Posted March 24, 2015 Report Posted March 24, 2015 Maybe pull that injector see if you see anything in it? -Robert Quote
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