Marauder Posted January 25, 2017 Author Report Posted January 25, 2017 15 minutes ago, cctsurf said: I would say that it is definitely the engine drooping on the mounts. You will either need to shim it up (according to LASAR's specifications) or replace the motor mounts or both. BTW, getting your engine square with the world is a great speed mod, it adds a couple of mph and no STC required. Right now your engine is pulling you down, not a good thing for an airplane that is supposed to be going up. If I picked up any more speed, no one would believe I am flying an F. 1
bonal Posted January 25, 2017 Report Posted January 25, 2017 You say there is evidence of some cowl rubbing does your F have harmonic balance rpm restrictions and if so is that where the issue (noise) is. I would definitely want to get new mounts or at least shim it up a bit. Things look very tight against your closure. Also the lower passenger side mount looks to be very close on the washer. 1
Marauder Posted January 25, 2017 Author Report Posted January 25, 2017 6 minutes ago, Andy95W said: It's just strange that it happened rather quickly over a relatively short period of time. Is the new vibration more of a low-pitch, or high-pitch variety? If it was low pitch, I would assume engine mounts had grown old and hard. If more of a high pitch, I would assume they were sagging and your engine was now contacting something it didn't used to contact. But none of that explains the odd angle for your intake boot. Good luck, Chris. It is strange Andy that it occurred rather quickly. Which makes me wonder if there is either something else going on other than the mounts. I also wonder if a mount could crack and not show any signs externally? It is hard to describe as a sound. It purely is a vibration that wasn't there before. If there is any sound, it is low pitch.
takair Posted January 25, 2017 Report Posted January 25, 2017 Chris Could be that the rubber mounts finally got to the point where there is not much left to do any cushioning. The lower one appears to be to the point where the forward one...under compression...is quite compressed. Note that the aft one is extended outward significantly. It might be to the point that you actually have slop in there...kind of like what happens to the gear pucks. If you had the cowl off, an engine hoist at the lift point would tell you how much you are sagged. I would lean toward the rubber mounts. When the cowl is off, have them look at the welds too...they have cracked on Mooneys.
Browncbr1 Posted January 25, 2017 Report Posted January 25, 2017 It is weird that your ram air boot seems to indicate the opposite of sagging engine mounts. Did you check to ensure the lower cowl is secure to the firewall and steel tube stays? I don't think my boot is that sharp.
Marauder Posted January 25, 2017 Author Report Posted January 25, 2017 27 minutes ago, takair said: Chris Could be that the rubber mounts finally got to the point where there is not much left to do any cushioning. The lower one appears to be to the point where the forward one...under compression...is quite compressed. Note that the aft one is extended outward significantly. It might be to the point that you actually have slop in there...kind of like what happens to the gear pucks. If you had the cowl off, an engine hoist at the lift point would tell you how much you are sagged. I would lean toward the rubber mounts. When the cowl is off, have them look at the welds too...they have cracked on Mooneys. Thanks Rob. I have a friend with an engine lift and will see if I can it over to my airport to check the sag. I tried to look over the entire mount and didn't see anything obvious. I did see something on one of the photos above that I will check on the plane (pilot side top mount -- the weld). Thanks for the suggestions.
Marauder Posted January 25, 2017 Author Report Posted January 25, 2017 43 minutes ago, Browncbr1 said: It is weird that your ram air boot seems to indicate the opposite of sagging engine mounts. Did you check to ensure the lower cowl is secure to the firewall and steel tube stays? I don't think my boot is that sharp. Yeah, I pulled and tugged on everything. Nothing appears loose.
Marauder Posted January 25, 2017 Author Report Posted January 25, 2017 You say there is evidence of some cowl rubbing does your F have harmonic balance rpm restrictions and if so is that where the issue (noise) is. I would definitely want to get new mounts or at least shim it up a bit. Things look very tight against your closure. Also the lower passenger side mount looks to be very close on the washer. The range is 2100 to 2350 and the only time I see that is when I am pulling back power to land. I do think the gap is close especially the lip on the spinner. It can't be more than an 1/8" from the lower cowl enclosure. Sent from my iPad using Tapatalk
Marauder Posted January 25, 2017 Author Report Posted January 25, 2017 air boot looks about right. Thanks Yetti. It looks similar to mine. Sent from my iPad using Tapatalk
Guitarmaster Posted January 26, 2017 Report Posted January 26, 2017 Didn't get any under the cowl, but I have solid 3/4" clearance on the cowl closure.
Marauder Posted January 26, 2017 Author Report Posted January 26, 2017 Didn't get any under the cowl, but I have solid 3/4" clearance on the cowl closure. Thanks for posting these pix. I am still looking for some old pictures I have of my plane. I think at one time my gap was closer to what you are showing. Sent from my SM-G900V using Tapatalk 1
cliffy Posted January 27, 2017 Report Posted January 27, 2017 Just a couple of thoughts I've had the alternator bracket break at the engine case and the tension arm broke also later. Wiggle the alternator when you can get to it. Long shot- look at the 4 bolts that hold the mount to the firewall and look closely at the mount itself for a cracked tube. You can lift the engine, loosen the bottom mount bolts and shim the bottom mounts without removing the bolts by slotting the washers the size of the bolt hole. Add 1/4 inch of shims both sides bottom and go fly to see if it is the mounts. Quick and easy. If you do change the mounts for new be sure to torque them to the correct torque rather than the old way of tightening until you think it is squeezed enough. There is a specific torque for the mounts to isolate vibration best. How old are the mounts?
Hank Posted January 27, 2017 Report Posted January 27, 2017 I've been checking my alternator security ever since I found one of it's mounting bolts laying inside the bottom of the cowl several years ago. Reach in and pull the belt on the left, then reach down on the right and see if it wiggles. After reading all of this, I think I need to check my engine mounts,too. The lower gap is getting small. And I just finished annual!
Marauder Posted January 27, 2017 Author Report Posted January 27, 2017 4 hours ago, cliffy said: Just a couple of thoughts I've had the alternator bracket break at the engine case and the tension arm broke also later. Wiggle the alternator when you can get to it. Long shot- look at the 4 bolts that hold the mount to the firewall and look closely at the mount itself for a cracked tube. You can lift the engine, loosen the bottom mount bolts and shim the bottom mounts without removing the bolts by slotting the washers the size of the bolt hole. Add 1/4 inch of shims both sides bottom and go fly to see if it is the mounts. Quick and easy. If you do change the mounts for new be sure to torque them to the correct torque rather than the old way of tightening until you think it is squeezed enough. There is a specific torque for the mounts to isolate vibration best. How old are the mounts? Thanks for the suggestion on the alternator. I will be going to the airport tonight to pull the cowl again to look closely at everything again. As for the age of the mounts, I thought they were changed out 10 years ago, but I cannot find anything noted in the logs. I am wondering now if they weren't and if that is the case, the last time they were changed out was the prior engine rebuild. 1
Marauder Posted January 28, 2017 Author Report Posted January 28, 2017 I'm being Inspector Clouseau this morning. Anyone know the acceptable movement of the lower cowl on a vintage Mooney? Other than support from the top and cheeks, what keeps it from moving up? Sent from my iPad using Tapatalk
takair Posted January 28, 2017 Report Posted January 28, 2017 Mine is a little older, but it does not move at all. The tubes on either side keep it quite stiff. There are two hidden bolts between the top cowl and bottom, in the front, at the seams. These are often forgotten and are considered structural. Check that those aren't missing (if your year even has them). 2
Guitarmaster Posted January 28, 2017 Report Posted January 28, 2017 Mine doesn't move at all.Sent from my XT1585 using Tapatalk 1
Marauder Posted January 28, 2017 Author Report Posted January 28, 2017 Mine doesn't move at all.Sent from my XT1585 using Tapatalk I'm looking for the attachment points. All I see are the points at the firewall.Sent from my iPad using Tapatalk
Marauder Posted January 28, 2017 Author Report Posted January 28, 2017 There needs to be something up front to hold it in place. Haven't found it yet.Sent from my iPad using Tapatalk
carusoam Posted January 28, 2017 Report Posted January 28, 2017 My C had two steel tubes that would require compression to move the lower cowl up. Check for the screws holding any supports in place... Best regards, -a-
carusoam Posted January 28, 2017 Report Posted January 28, 2017 Bug: Simultaneous posting causes DPs... -a-
Marauder Posted January 28, 2017 Author Report Posted January 28, 2017 The only I found is a single bracket attached at the front of throttle body. Doesn't look like it is providing any up and down support.Sent from my iPad using Tapatalk
takair Posted January 28, 2017 Report Posted January 28, 2017 Only photo I could find real fast. Note the black tube at the lower portion in the photo. It attaches to the firewall and the bottom cowl. Second photo is partial close up. 1
Marauder Posted January 29, 2017 Author Report Posted January 29, 2017 Only photo I could find real fast. Note the black tube at the lower portion in the photo. It attaches to the firewall and the bottom cowl. Second photo is partial close up. I definitely don't have that tube. I have been able to confirm I have the "hinge" mounts. I will need to remove the lower cowl to change out the mounts. It looks like two screws on the firewall, the bracket from above, the oil cooler, the ram boot and cable and air intake.Looks like a trip to the shop...Sent from my iPad using Tapatalk
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