Davo

I have been really busy and haven't had time to post the result of this work. After top end work as noted above, the engine is smooooooth! Did a few ground runs as recommended by Zepherhills Aircraft engines and waiting on CHT probes before flying so we can monitor each cylinder.

I found the pushrod tube for #4 exhaust was worn more than 50% through the wall and need to replace it. Fixing what was rubbing, of course. Unfortunately, the part seems difficult to find. I don't know the part number but it is for an IO-360 A3B6D. If anyone knows of one and/or the part number. I would be very grateful. Thanks, Dave

Same thing happened to me. I found the original part number at avnet.com and ordered 2 for about $12 each. Google part number SG40281B1-D05U-G99. Easy to replace and has worked perfectly since.

Result of inspection by Zephyrhills Aircraft engines is the valve stem was "on the way to a complete failure of the exhaust valve" LJ made mention that, on the Mooneys, the #4 cylinder is the most prone for issues such as this. Does anyone have more on this? Looking through the last annual, they made note that #4 was staked then had good compression, still does. Should I send #4 away or follow closely?

Checked intake system. It's tight. Tried several methods and all checked fine.

Update on the rough running. Put a dial indicator to compare lift on the cylinders with good compression with the #1. No difference. We reamed the valve guide and tested compression. Back to 78/80. Ran the engine and started smooth, turned rough after about a minute. RE-checked compression and back down. I've since pulled #1 and sent it off to Zephyrhills aircraft engines. I've known the previous owner (Charlie Meloit) and the new owner LJ Warren since early 2000's and they did fantastic work on a Trinidad I had. Honest and very fair, not to mention meticulous work. I gave LJ the story so far. I'll report his findings. I know when I 'm at my limit and need help.

Basic question....is there a way to bleed the hydraulic lifters with the cylinders and pushrod tubes in place on the IO360 A3B6D?

Good idea. Thanks!

A friend recently purchased a Mooney M20J with an IO 360 A3B6D with approximately 600 hours on the engine since major overhaul through a respected engine shop. Logs are pretty complete all done through a Mooney service center in Florida since new. The only thing I don't see anywhere is the 500 hour service to the mags. The elevator controls were really stiff but, through great feedback, we resolved that easily with proper lubrication and cleaning. Anyway, he purchased it about 2 weeks ago and flew it to Northern California form the Phoenix area feeling it ran well. He wanted me to fly it last weekend. It felt rather rough on start up but run-up felt smoother with mag drop WNL. Applied power and I thought this was accelerating kind of slow. I passed this off as being used to my -9A. Climb out was dogged to say the least climbing at 400 fpm at 85 kts from an airport 160 feet MSL. I immediately returned to the airport thinking this wasn't right. My friend is an A&P and as a favor, started to look things over with me. We checked plug wires then plugs. All good except for #1 which had a pretty good soaking of oil top and bottom. Compression was 0 on #1 but 78 on the others. Staked the valve with no improvement. Definitely heard the hiss of air through the exhaust so, naturally, we thought the exhaust is valve stuck open. Borescope showed good movement and minimal crud on the seat. Cylinder walls looks perfect. We lapped the valve and checked valve guides. Compression came right up to 78/80 so we thought we're home free. Nope! started her up and still runs really rough. #1 is notably much cooler to the touch than all the others. (The insight CHT/EGT gauge is inop). Checked fuel flow at the injectors and is even all the way around. Restrictors are clean. Starts well but runs very rough. Swapped plugs around but the problem stayed with #1 cylinder. So, I've got compression, fuel and air and the only thing I can think of that's left is spark. It's not the plugs since the rotation changed nothing. This has the dual (2in 1) magneto we all love so much but the mag drop on a run up is about 75 RPM. My A&P friend only works on airline jets for the past 25 years and he's stumped as well. I'm at the limit of my skillset and this is a certified plane so I can't really go any further, nor would I. He's going to try to find one of the local A&Ps that work on the field. I would really like to understand what could be the problem. I don't know how much resistance the plug wires should have but measures at 70.5 ohms. Any ideas?

Thanks.

Follow up to everyone's advice. The bungee's were quite dirty, caked with old lube. I cleaned and sprayed/soaked with dry silicone then turned my attention to the yoke, cleaning the push rods and controls then spraying with silicone as well. Now everything is smooth as silk. Thanks for the guidance. This aircraft will definitely need some TLC to get her where she needs to be.

Y'all are great. This helps much. Thank you!

Great stuff, everyone. Thanks for sharing your experience. I will try those tips and see. It's likely I'm just older and weaker!

Yes, I read it, thanks.

My friend just purchased a 1989 M20J and couldn't wait for me to fly his new plane. There is a lot to like about this plane and I was excited to fly it. I have about 750 or so hours on various Mooneys but that was 30+ years ago so my recollection of the flight characteristics is nill. I was a bit surprised on the force needed to take off and land. Trim was set properly and manual trim moves free and easy. W&B is good. I know saying it is "heavy" is a subjective description but, it just seems to take way more effort than is expected or remembered. The plane had a pre-buy, but that means little as I found the oil filter safety wired wrong and the landing light disconnected. I'm thinking a systematic approach to the controls with cleaning and/or lubrication may be of some benefit. I just wanted to get some feedback from those of you much more familiar and current in M20J model whether the plane is characteristically heavy in pitch of not. Thanks for your time and experiences.