Z W

Our M20C had one of the Brittain systems, can't remember which any more, but it would fly the heading bug perfectly. No altitude hold, but once you had it trimmed out in cruise, you could usually hold altitude +/- 10 feet by leaning forward in your seat to go nose-down, and back to go nose-up, or bending your knees and pulling up your feet a little closer. Made for a fun game on a long cross-country.

I sold a 430W last year for $4,000.00, removed for an upgrade. I posted it here and on Beechtalk, never got to Ebay. Someone posted here that was way too much, but someone on Beechtalk bought it the day after I listed it, no questions asked. They were being listed for that or a little more at the time everywhere I looked. It was in really nice shape. Prices may have gone down, but there's one data point. Best of luck to you.

I would start by pulling the carpet and any padding under it, and then applying high-quality duct tape over all the holes and gaps in the floor, if someone hasn't already done that. There are a lot of holes and gaps. This has a bonus benefit of keeping loose/dropped hardware, dirt, and gunk from falling down inside your floorboards too. If that doesn't fix it, you can move on to checking the cabin penetrations one by one.

I have the YD. I can tell there's a big difference when it's on in stability. It's a very nice feature to have and I use it on every flight. I'll admit to failing to turn it off at least once and landed with it engaged. Not recommended, but it's a non-event from a safety perspective. Didn't even notice it until I'd cleared the runway. Lesson learned and now I use the AP Disconnect button on the yoke to turn the autopilot and YD off for landing, and not the "AP" button on the GFC500 control panel, which leaves the YD engaged.

I left Durango this month with an adult passenger, a cargo area full of bags, and 6 hours of fuel on board. Headed east, pointed straight at the Rocky mountains. Climbed 500-700 FPM up to 17,500 feet, straight over those mountains with 4,000 feet of terrain clearance, no circling required, no mountain wave concerns. Caught a tailwind of up to 70 knots, and made it to the Kansas City area in a little over 3 hours. Smooth air, no clouds, no traffic, within glide distance of multiple airports almost the whole time. Didn't even make a radio call between leaving the pattern in Colorado and entering it in Missouri. 175 KTAS at 13 GPH (TIT limited, I like to keep it under 1600). Landed with 2 hours of reserve fuel. Some days the turbo really shines.

I put mine back together incorrectly a couple of times which made me think it could be clocked wrong. I'm not 100% sure either though, it was some time ago. I just remember having to take it back apart again to get everything lined up as it should be.

Those look like the same caps on my K. If so, they are a two-piece design held together by a bolt, nut, and cotter pin. If you remove the cotter pin and nut, you may be able to "clock" the top piece differently to orient your tab to match the other side. Note - the tightness of your cap tab is determined by the torque of the nut. If it's too tight, loosen the nut a quarter or half turn, replace the cotter pin, and try again. Fought too-tight caps for years before I learned this trick. There is an internal O-ring on the bolt that keeps water from running down the inside of your cap into your fuel tank. Good time to replace it with a fluorosilicone version while you have it apart.

Those look good, and stout. Only feature you may be missing is a way to lock the jacks up so that you could leave the plane on them for an extended time without relying on the hydraulics. Some use a locking collar, something like this:

I had the same experience with fuel seeping out of one of the rivets near the fuel valve. When tightening/loosening the fuel valve you could actually see this rivet move slightly. I applied Oyltite to the rivet while turning on the fuel sump drain to move the rivet and tried to really work the stuff in there. It stopped the leak. That was in January of 2024, so it's held up for almost a year now. Link to buy the stuff: https://www.amazon.com/Co-11475-Oyltite-Stik-Temporary-Low-Pressure/dp/B002C3L5NO The other fix is apparently to drain the tank, open the top access cover, drill out the rivets, and replace them "wet" with fuel tank sealant. A much more involved job. I have had fuel valves go bad internally - there's another O-ring inside them that can fail. So I now keep a spare in the plane. More often though, it's just a small piece of debris inside the valve that's keeping it from sealing, and vigorously working it up and down with the sumper will dislodge the item and let it seal back up. Be careful installing new valves - the torque required is shown on the packaging in inch pounds, not foot pounds, and they are delicate brass that can snap off. They're barely snugged in there, just enough to seal the external O-ring against the wing.

You can go to www.g100ul.com, input your airframe and engine information, input your credit card information, click a button, and download your STC to use unleaded fuel. It takes just a few minutes and costs $450.00 for a Mooney. @bonal all of your concerns have been discussed at great length in threads on Beechtalk.com, with active participation by the owners of GAMI. There are videos on Youtube of them addressing them at forums at Oshkosh as well. I have followed along for years now and do not have any concerns about the new fuel. Your opinion may vary.

Mine is the same - put 8 quarts in at oil change, it will read 7 on the dipstick after first run. If I add another quart then to go back up to 8 quarts on the dipstick (which is in reality 9+ quarts in the engine), it blows out pretty quick. It holds between 6 and 7 on the dipstick pretty good so I let it get a little below 6, then add a quart. I believe this maintains 7-8 quarts actually in the engine. It used to hold less and would blow out anything over 6, so I would only put in 7 quarts at oil change, which would then read 6 quarts on the dipstick, and wait until 5 quarts to add, which did work fine. Cleaning the oil and sludge out of the air/oil separator and replacing the oil cap gasket seemed to help and now it'll hold another quart. I believe that reduced the crankcase pressure, or helped it properly escape the engine.

Do future you, future avionics shops, and future caretakers of your plane a favor - pull everything unused and inop out of the plane, or fix it. Our Pulselight was inop. A while back, asked the avionics shop to either fix it or remove it during some work, whichever was cheaper. It came back without the Pulselight. Haven't missed it. Extra system, extra maintenance, extra weight, and in my opinion, of little value with LED lights all around. Your opinion may vary of course.

Well now we have another Mooneyspace controversy. Mine has always been loop towards the nose. I didn't know you could reverse it. I'll have to try and see what that does.

My M20C would foul a plug (with lead) if you did not lean for taxi. I do not remember at this point how the fuel system was setup, may not have ever been verified to be to factory specs. But I can verify that at least some of them do it out in the wild. My current M20K will also do it, though not as quickly. I know its fuel system is set on the very rich side of factory specs for extra cooling in the climb, which works well. But the tradeoff is you have to lean for taxi. I just had this thought because the OP seems new to this engine and was reporting fouled plugs while leaving the mixture too rich, and everything else seemed normal. Leaning for taxi would be an easy thing to try to help identify the real problem.

Just a thought - were you leaning aggressively for taxi and ground operations? Many engines will foul a plug with lead deposits from fuel if you leave the engine full rich on the ground, especially if you're above sea level altitude. It will present as a large drop in RPM and rough-running engine during the mag check. The cure is to do a very lean run-up at possibly higher RPM (2,000 or so for a minute or two) and burn off the lead deposits.