Supercop0184 Posted April 10, 2019 Report Posted April 10, 2019 Sunday I was out flying my 64C model Mooney. Before taking off from my first airport, I did a full run up and everything checked fine. I flew to a second airport, picked up a passenger, did a Nother full run up and everything checked out fine. We flew to our third airport, Landed and talked with some other people for about an hour. Got back to the airplane, went and did another full run up, and ran into problems. During this third runup, my mag check went as follows. Engine seemed to be running fine on both, switched over to left, and no drop or change so back to both. Switched over to Right, and The engine began to die so back to both and power came back. After toying around with this a few times, I determined that if I switched it to right and left it, the engine would die. I taxi back to the ramp where we began testing a few things. We called a couple of contacts who said that they believed it was either the ignition switch, or the P wire. A friend of mine with an ohm meter came out and checked the lead wire to the right mag, which showed continuity whether or not the ignition switch was selected on right, left, or both. After doing some research, this led him to believe that it was an ignition switch problem. He disconnected the mag, saying that with the wire disconnected, the mag would be hot all the time. We started the engine back up and did another mag check . The results were the same as the previous. Both ran smooth, left had no drop no change so back to both, Right began to kill the engine. Any ideas on what this might be? I am not a mechanic, and have given you all the information that I have and know. Quote
RLCarter Posted April 10, 2019 Report Posted April 10, 2019 With the P-lead disconnected sounds like a dead mag, assuming it was disconnected at the mag Quote
carusoam Posted April 10, 2019 Report Posted April 10, 2019 SC, No engine monitor, for data sharing? the following is PP thoughts only... i’m Probably going to mess up an important detail... The switch operates the mags by allowing them to ground or not... If they get grounded, they don’t work... So the run-up grounds one mag, then the other, with not grounding both in between... I believe they are grounded using the P lead... in the event of a broken P lead... no ground is made, and the corresponding mag is live... no matter what happens to the switch... When there is no change from both to one... this is a hint the second mag is not contributing anything... When you go from both to the other... the engine dies... this is confirmation that the other mag wasn’t contributing anything, and when relied on... it gave nothing... So... it looks like you have a bad mag situation... what is causing the bad mag situation is the question of the day... Something maybe isn’t ungrounding the mag... allowing it to run... checking the switch output with a voltmeter / continuity test, seams like an appropriate idea... I believe you said you did this, and the mag didn’t un-ground no matter what the position of the switch was... Check your logs to see how original the ignition switch is, and how many hours on the mag... it is possible the mag croaked... If you have JPI data... this would be helpful to review regarding the run-up and mag test issues... Forwarding the question to the doc is a good idea... @M20Doc ignition switch or dead mag? The switch when tested has the bad mag constantly grounded...(?) Best regards, -a- Quote
Prior owner Posted April 10, 2019 Report Posted April 10, 2019 If you started it with the right mag hot, I would have expected it to kick back on start up, and probably not start.... so maybe a mag problem..? You might want to check a few threads down regarding starting problems- I posted a link to the ignition switch SB and an article that describes some of your symptoms. Did the engine start smoothly/normally with the right mag p-lead removed? might be your switch...might not. You can check continuity and absence of continuity with the switch in different positions, per the SB with or without the engine running. if you checked continuity of the right p-lead with it still attached the mag, you need to remove the lead from the mag and check it again, because the points will show the mag grounded depending upon the position of the points. 1 Quote
7.Mooney.Driver.0 Posted April 10, 2019 Report Posted April 10, 2019 I had a similar issue happen to me and it turn out to be fouled spark plugs on the right side. I tried this and it fixed my problem https://pilotworkshop.com/tips/clearing_fouled_plug/ Good luck friend. Hopefully is just fouled spark plugs. Sent from my iPhone using Tapatalk Quote
Guest Posted April 10, 2019 Report Posted April 10, 2019 Spark plugs are easy to remove and check. A shorted P lead, faulty switch or a bad magneto. Some magnetos have and internal grounding strip which grounds the mag when the P lead is removed, others have a threaded stud. I use my Eastern Electronics magneto synchronizer to test the P lead and switch by disconnecting the P leads at the mags and connecting to the P leads. Clarence Quote
Supercop0184 Posted April 10, 2019 Author Report Posted April 10, 2019 48 minutes ago, M20Doc said: Spark plugs are easy to remove and check. A shorted P lead, faulty switch or a bad magneto. Some magnetos have and internal grounding strip which grounds the mag when the P lead is removed, others have a threaded stud. I use my Eastern Electronics magneto synchronizer to test the P lead and switch by disconnecting the P leads at the mags and connecting to the P leads. Clarence Ok - yeah I would bet money it’s not a plug issue / that would affect fire coming into the engine. Unless all four plugs on the right mag went tits up at the same time. I guess weirder things have happened. Quote
Supercop0184 Posted April 18, 2019 Author Report Posted April 18, 2019 Ok yall - I sent the MAG to a MAG shop for inspection - while it is old, it is running properly. This is quite baffling to me. Theoretically, if the P lead is disconnected - the MAG should be hot - but it wasn't. That is what led me to believe that it was the MAG, Because it was dead even when disconnected from the ignition switch and the lead wire. What else could this be? I don't have engine monitor info to share. I cant imagine its plugs - It would have to be ALL four plugs controlled by that MAG SO fouled out that its dead. I could see a very rough running engine being plugs on a MAG, but all of them? Could the "distributor" cap be bad somehow? Could something in the cap leading to the plug wires cause the whole mag to shut down? Sorry for the questions - just trying to learn this airplane and trouble shoot some here! THANKS! Quote
Supercop0184 Posted April 18, 2019 Author Report Posted April 18, 2019 On 4/10/2019 at 12:47 AM, carusoam said: SC, No engine monitor, for data sharing? the following is PP thoughts only... i’m Probably going to mess up an important detail... The switch operates the mags by allowing them to ground or not... If they get grounded, they don’t work... So the run-up grounds one mag, then the other, with not grounding both in between... I believe they are grounded using the P lead... in the event of a broken P lead... no ground is made, and the corresponding mag is live... no matter what happens to the switch... When there is no change from both to one... this is a hint the second mag is not contributing anything... When you go from both to the other... the engine dies... this is confirmation that the other mag wasn’t contributing anything, and when relied on... it gave nothing... So... it looks like you have a bad mag situation... what is causing the bad mag situation is the question of the day... Something maybe isn’t ungrounding the mag... allowing it to run... checking the switch output with a voltmeter / continuity test, seams like an appropriate idea... I believe you said you did this, and the mag didn’t un-ground no matter what the position of the switch was... Check your logs to see how original the ignition switch is, and how many hours on the mag... it is possible the mag croaked... If you have JPI data... this would be helpful to review regarding the run-up and mag test issues... Forwarding the question to the doc is a good idea... @M20Doc ignition switch or dead mag? The switch when tested has the bad mag constantly grounded...(?) Best regards, -a- Mag hasn't been overhauled in ages! But the MAG shop says shes still ticking - Switch I couldn't find - but TBH haven't specifically looked for it yet - Wouldn't be surprised if it was original. But yes, the MECH checked continuity - funny thing is, the P LEAD for right MAG wouldn't GROUND - indicating always hot. WEIRD! 1 Quote
Guest Posted April 18, 2019 Report Posted April 18, 2019 9 minutes ago, Supercop0184 said: Ok yall - I sent the MAG to a MAG shop for inspection - while it is old, it is running properly. This is quite baffling to me. Theoretically, if the P lead is disconnected - the MAG should be hot - but it wasn't. That is what led me to believe that it was the MAG, Because it was dead even when disconnected from the ignition switch and the lead wire. What else could this be? I don't have engine monitor info to share. I cant imagine its plugs - It would have to be ALL four plugs controlled by that MAG SO fouled out that its dead. I could see a very rough running engine being plugs on a MAG, but all of them? Could the "distributor" cap be bad somehow? Could something in the cap leading to the plug wires cause the whole mag to shut down? Sorry for the questions - just trying to learn this airplane and trouble shoot some here! THANKS! Some magnetos have an internal contact bar which contacts the P lead end when the P lead in installed. When the P lead is removed from the magneto it grounds the magneto internally, avoiding a hot mag. Clarence Quote
Prior owner Posted April 19, 2019 Report Posted April 19, 2019 (edited) Can you borrow a pigtail for your mag-? once it’s installed and timed, you can use the pigtail to keep the internal bar depressed while remaining disconnected from a ground. Don’t connect the pigtail to anything, then go start the plane, switch to the right mag and see what it does. If it still runs, it’s gotta be a switch issue? Maybe? did you check all switch positions with an ohm meter? Per this service bulletin: Bendix switch service bulletin Edited April 19, 2019 by PilotCoyote Quote
Supercop0184 Posted April 26, 2019 Author Report Posted April 26, 2019 Update: it was the P lead - ordered a new one - and got it put in. Got the mag timed tonight - tidied up some of the conglomeration of wires that were strewn about. Found three wires that, at one point, led to the switch - but had been cut in years past and taped. The OLD p lead had a butt splice - that’s where the failure was. I’m definitely glad I’m taking this opportunity to clean up some of the things that are never seen. Pulled the interior - redoing seat upholstery, headliner, and side panels while they’re out. Removed old insulation - pulled inspection panels below back seat - complied with SB208 while we were digging. Cleaned everything up - lubed what we could - shot some corrosion X in that area under the seat - shot some chromium phosphate on the cage for good measure. No corrosion found - what a great feeling. Waiting on new insulation from airtex which will be here Tuesday. Interior stuff should be done mid week - she’s gonna look sharp once it’s all said an done. Hopefully I can get her all buttoned up by next weekend - leaving for a couple of weeks and am supposed to fly her in for her annual on the 19th. If I can’t get it flying by the time I leave - I’ll have to reschedule my annual. Taking it to weepnomore July 26th, then in for paint in October. Woohooo 3 Quote
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