33UM20C

UPDATE - FIXED Apologies this took so long to be posted I completely forgot to to so. The Issue has been fixed. To quickly restate the issue, My 1963 Mooney M20C would refuse to start in ANY condition. It did not matter if it was 25 deg F or engine was flown and still hot - no start (for the most part) Here is the original diag list: Verified I have a SOS system in the plane Verified I can easily flood the carb when trying to start, so good fuel flow Boot pump works properly No containments in fuel lines Key ignition switch passed bench test & was cleaned and reassembled SOS system does enable when key is pressed and prop turns. I could not hear it over the prop at first SOS switch is ON SOS was jumped and buzzed as it should with all switches off With the starter disabled, spark plug lead removed and gapped above the block for grounding, no spark with SOS buzzing With the started engaged, prop turning, top plug lead disconnected and gapped to block, no spark was seen After this I did pull spark plugs and verified there was no spark using only the SOS. With my legality running out on how much I should be taking off my plane I called an A&P for some help. THE SOLUTION: After a quick explanation to the mechanic it was obvious the problem was narrowed down to the left magneto that housed the retard circuit. We pulled the leads off the mag and the top cover. The problem was the retard lead had literally never touched the contact inside the mag. It was bent wrong from the factory. After bending up the little U contactor and putting everything back together the plane started up perfectly normal. It has done so for months now. I will attach pictures of what I took but I don't have any of the specific U shaped metal, but its quite obvious where the lead touches. What boggles my mind is the mags have 250 hours on them. Speaking to the old owner he recounts that he got used to holding the key just until the starter engaged... so he never grounded and mags on startup *facepalm* Anyway many thanks to all that helped figure this out (especially @Shadrachfor his wealth of info and referring me to the A&P who fixed it) and I hope this helps somebody in the future!

I couldn't find a proper wiring diagram of the specific solenoid you have. But its probably P/N: 001464 if you want to keep looking or need a new one. Here's the service manual that has wiring diagrams for your M20E. Use the S/N to narrow your search if you need them 1966 Mooney-Service-Manual.pdf

Amazing information. My mechanic said he had a VERY similar thing happen to him on a piper Aztec. But you explained it in simpler terms for me. Going to look into this tomorrow thanks!!

I don't thin so, I made a map of the wires and labeled them etc. etc., But I never even took them off in the end. I just removed the back plate upside down and reinstalled the same way. Tested again and had the same results

There's a shop in Florida called Plane Exhaust. Highly recommend using anyone but them. They fully rebuilt my exhaust and baffling. Riser cracked within a few months which was found at its next annual. Shop was contacted and said they would not be fixing it as it was (approx. 3 days) over the 1 year warranty. The first part lasted 59 years for reference. I had it repaired by a local shop, I called them to ask for a %50 refund to pay for the fix, upon finding out it was fixed they asked me to send it to them "for free repair" I obviously did not. The owner is completely awful to talk to, he insulted and yelled at me for 5 min on the phone before hanging up on me. Out of spite for how annoyed I was with they're customer service I pestered them for a refund. Owner finally offered me $100 back (%15 or so back). I accepted the offer and never received the money. Its been 2 months so I don't think its coming.

Looking for opinions on this problem I'm having. I've been working with @Shadrach on this issue and has been extremely helpful thus far with his wealth of knowledge, but it seems like we've exhausted all our options that we can think of. So I'm looking to MS to provide some out of the box thinking - or just prove our thinking. I've got a 1963 M20C S/N 2465 with the IO-360 A1D. The problem: Extremely hard to start (hot or cold), seems to always start when I release the key back to 'Both' and kicks on RIGHT AWAY like its been trying to start the whole time. All signs pointed to an ignition problem at startup because the plane ran fine once started, but even hot would not restart after a simple refuel stop. So far in the search this is what has been done: Verified I have a SOS system in the plane Verified I can easily flood the carb when trying to start, so good fuel flow Boot pump works properly No containments in fuel lines Key ignition switch passed bench test & was cleaned and reassembled SOS system does enable when key is pressed and prop turns. I could not hear it over the prop at first SOS switch is ON SOS was jumped and buzzed as it should with all switches off With the starter disabled, spark plug lead removed and gapped above the block for grounding, no spark with SOS buzzing With the started engaged, prop turning, top plug lead disconnected and gapped to block, no spark was seen With this info we assume that there is a problem going on between the wire from the SOS to the spark plug lead ends.. I.E the left magneto. Does anyone have any ideas on this or simple ways to bench test the SOS? Is there something that could of been knocked out of place or put back together wrong during annual? I've read through Don Maxwells article and tried to recreate what I could with my limited tools at my last visit to the airport. A bit of background - I just bought this plane and it Immediately started happening after the Annual Inspection which was my Pre-buy. Previous owner in still in contact and says he never experienced this happening, mechanics said it started perfectly every time and I have no reason to not trust them as they are my local mechs with no connection to the previous owner. Thanks everyone for your ideas!

@Shadrach That would be great. I'm going to be out of the country for another week. When I get back lets set something up! Il DM you as soon as I'm home.

On that flight I can specially say no, it was not. Only because that was before I owned the plane. Its been a couple flights and I've forgotten at what point / when I did the mag check. But what you pointed out is what annoys me the most. Its perfect for some time then with no FF change or RPM change the EGT's get very high... I did not fly this flight but in checking every other readout the EDM shows nothing else spikes like the EGT's do here. I guess that's what I want to explain.. Why the wide spread when the engine heats up?

Yes, It ran rougher as expected but no cylinder went offline and temps seemed to stay relative.

Hey guys this post is sort of an addition to my other post here but looks like the discussion evolved into other things so I'm going to start a new one with some updated info and new questions for you all. As the last post states I was having some engine roughness I.E vibrating intermittently after it was hot, as well as very high EGT's on Cylinder #1. I changed the spark plugs even though they all looked fine, now running Tempest Massive ones. It seemed to fix the roughness as the engine runs smoother now, I'm also a stickler about aggressive leaning (just in case). My possible problem is a very wide EGT spread due to C#1 having a very high EGT. Reading this article here makes me want to shrug the situation off as a normal inconsistency and that I'm overthinking this whole thing. If you agree please tell me so. Here's the data from my EDM 830: Here you can see my takeoff just before where the curser is when the RPM in green shoots up. After a minute of so I transfer into a cruise climb but don't lean yet, C#1 in red EGT's continue to climb much higher and faster than the other cylinders. Its not great after that running at least 150-200 deg hotter than the others I wont include a CHT graph because its exactly what you should see, spread of about 60 deg F on CHT and C#3 the hottest due to its positioning. Here's the next day: As you can see C#1 peaked at 1670 deg with mixture rich on takeoff. It stayed hotter most of the time and had more dramatic rises and falls. Next day, I replaced all plugs with tempest massives and here is the data: Looking better, cylinder 1 is higher but this can be chalked up to placement of the probe and general inconsistency. I was happy with this flight and its temps. Note that the sharp arm rises for 1 minute at a time were post maintenance WOT run ups. Here's the last day I flew: All the peaks on the right were me doing touch and goes. Things look okay on the touch and go side but over in the cruise and pre maneuver side you can see the curser on a particularly wide EGT spread. That curser mark was probably mixture rich because I was maneuvering. My questions for you guys: 1. Am i crazy or is this EGT spread a little too high, with peaks too high? 2. Is there a problem here or can I chalk this up to be placement errors, probe errors and general inconsistency? For reference here is a cruise flight from the previous owner: Some things to note: This info was pulled from a JPI EDM 830 Aircraft: 1963 Mooney M20c IO-360 Passed annual last month, they borescoped the cylinders and said they were fine Changed spark plugs last week Brand new baffling 600 hrs. on the engine and good compression 72/80 on C#1 Thanks guys!

I was going to say the same thing. Probably just the Holiday

UPDATE: I went out yesterday and tried to get it started to no avail (with a preheat). With no preheater available today (as is most days) and no electricity to plug into I created a little battery cart that converts DC batteries to A/C power that my block heater can run on. So today I hooked it up to the block heater while I pulled the cowl off etc. All plugs and leads looked fine to me but the champion plugs got ~300 hrs. on them as is and show a little wear n tear. Since I don't have a tester I said screw it and replaced all 8 with Tempest UREM38E's (massive). With the cowling open to the wind and preheater only on for 1.5 hrs. the oil was about 50 deg F when I went to start. It was a little hard to start but started on my second round of 10 seconds on the starter. Everything ran as normal passed a regular runup, LOP runup, WOT runup, and flew great. All EGT's stayed normal and within 15 deg of each other on the WOT test. All CHT's stable as well. No shake in flight. So this seemed to of done the trick. I'm also burning 19 GPH on takeoff instead of the 11.3 I had last week. Thanks everyone for they're input I learned a lot!

I agree, I should do more testing. Problem is I cant. Becuase im below my insurance hours minimum I cant fly the plane and I cant get it to recreate the problem on the ground. I need to fly with a CFI but its hard to ask sombody to drive to meet me for a 15 minute diag flight when they live an hr away. By the time im done paying for their drive, air time, and plane tac time. Im in more than the plugs are worth to swap - and id still be running 300 hr massives so. Unfortunate situation but its the one im in.

Super informative video thank you! I pulled all 4 bottom spark plugs off today and all seems normal. cylinder 3 / 4 plugs has moisture on the threads but I assume that's from unburned fuel at shutdown? All looks super clean as they only have about 300 hours on them. I'm going to pull the top 4 Monday. didn't have time today because they're so much harder to get to.. if anyone has tricks to it let me know. Prob just going to buy a set of 12 Tempest UREM38E massives and put all new plugs in as I hear online some champion plugs have a lot of problems and Tempest will burn better as well as make everything smoother for longer. Attached is what the plug on C#2 looked like. They all looked the same except a little bead of lead on C#3

So a plug failure could result in High and low EGT? Could you explain that to me to I could better understand both scenarios?