I completed the annual inspection on my RV-10 today and part of that was to do the SB on the Slick mags replacing the cam and brush. I'm glad I did because the brushes were way out of spec according the the SB and I only had 80 hours on the mags so If you're holding out I suggest you check yours. Anyhow, during the mag check when switching to the left mag the engine would shut down. Right mag ran fine. P-leads, ignition switch all good. My guess is I didn't seat the brush fully in the cap when I replaced it. Any other suggestions? I work in the middle of nowhere during the week and only have Saturdays to play with the plane so I have a week to think about it before I get a chance to pull the mag and find out. Both the left and right mags are timed perfectly (buzz box) so I know it's not the points, only thing left is the brush unless someone can tell me another area I may have missed. I want to make the most of my time next weekend so any and all suggestions are welcome.
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Left Mag not operating
- Thread starter Rick S.
- Start date
Gary 40274
Well Known Member
Broken P Lead wire
Sometimes when working on the mags it is possible to break the wire that goes from the P lead up to the switch and back. Try checking it for continuity to ground when off and open when switch is on.
Gary Specketer
Sometimes when working on the mags it is possible to break the wire that goes from the P lead up to the switch and back. Try checking it for continuity to ground when off and open when switch is on.
Gary Specketer
A broken "P" lead will make the mag hot all the time. His does not operate.
When you timed the mags, are you sure you let the impulse coupling snap before timing the left one?
Yes...when pulling through the prop the inpulse coupling engage or snapped, then kept rotating until left mag would "buzz" and the right was almost at the same time or actually at the same time...best timing I have done to date...patted myself on the back for how close they were
Thanks Gary, I checked that, Something tells me I didn't do something right when I swapped out the cam and the brush.
Yes...when pulling through the prop the inpulse coupling engage or snapped, then kept rotating until left mag would "buzz" and the right was almost at the same time or actually at the same time...best timing I have done to date...patted myself on the back for how close they were
I'm sure we're talking correctly here, but just to confirm; the impulse will snap at approximately "0" degrees, you must then back the prop to the 20/25 degree mark to properly set the left mag timing.
Umm.
What you are describing is setting the left mag timing exactly 180 degrees from where it should be. After the impulse fires, you have to back the prop up as Mel described.
Or, you could have timed the mag on the exhaust stroke instead of the compression stroke. Just a thought.
Yes...when pulling through the prop the inpulse coupling engage or snapped, then kept rotating until left mag would "buzz" and the right was almost at the same time or actually at the same time...best timing I have done to date...patted myself on the back for how close they were
What you are describing is setting the left mag timing exactly 180 degrees from where it should be. After the impulse fires, you have to back the prop up as Mel described.
Or, you could have timed the mag on the exhaust stroke instead of the compression stroke. Just a thought.
7DeltaLima
Well Known Member
Rick,
I had the right mag go bad a couple weeks ago. Just quit working similar to what you describe. Buzz box timing still worked. Points still opened and closed. Worked one day, didn't the next. New Slick mag... 50 hours on the RV10. After assuming I'd done something wrong and chasing all the wiring down, ohm this, disconnect that.... you all know the drill.... Talked to Thomas at G3I and he talked me through how to check for a bad coil with an ohm meter... it was the coil bad. Go figure.
I chased a new coil down... learned how to pull the wedges out that hold the coil in... installed the new coil.... and reinstalled and all is well. Guess that's why there are two of them.
Doug
I had the right mag go bad a couple weeks ago. Just quit working similar to what you describe. Buzz box timing still worked. Points still opened and closed. Worked one day, didn't the next. New Slick mag... 50 hours on the RV10. After assuming I'd done something wrong and chasing all the wiring down, ohm this, disconnect that.... you all know the drill
.... Talked to Thomas at G3I and he talked me through how to check for a bad coil with an ohm meter... it was the coil bad. Go figure. I chased a new coil down... learned how to pull the wedges out that hold the coil in... installed the new coil.... and reinstalled and all is well. Guess that's why there are two of them.
Doug
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Jim P
Well Known Member
Nice timely thread for sure. I had a mag go bad on a Continental A-65 with the same symptoms. Worked one flight, completely dead the next. I'll go check the coil when I get around to checking the rest of it.
BTW, is there an easy way to pull the coil wedges? I've also read on the SAC Skyranch site, that pulling the coil can partially demagnatize the rotor if a bridge isn't used. Any experience with that?
Jim
BTW, is there an easy way to pull the coil wedges? I've also read on the SAC Skyranch site, that pulling the coil can partially demagnatize the rotor if a bridge isn't used. Any experience with that?
Jim
G3i Ignition
Well Known Member
Ether or, 180 degrees off or possibly a failed coil.
Before you remove the left mag to verify the above, pull the left mag plugs out and snap through the impulse coupler and watch to see if any of the plugs have a spark. Then ck #1 cylinder plug and reference with your timing mark on the flywheel. No spark?.Sounds like coil.
Here are the coil values from the Unison L-1363C 4300/6300 Series Magneto OH Manual
Coil Tolerances:
Primary Coil lead .50 ? 1.2 Ohms
Secondary Coil 13,000 ? 20,500 Ohms
Condenser .35 MFD +/- 10%
Excited for KOSH,
See you there
Thomas S.
Before you remove the left mag to verify the above, pull the left mag plugs out and snap through the impulse coupler and watch to see if any of the plugs have a spark. Then ck #1 cylinder plug and reference with your timing mark on the flywheel. No spark?.Sounds like coil.
Here are the coil values from the Unison L-1363C 4300/6300 Series Magneto OH Manual
Coil Tolerances:
Primary Coil lead .50 ? 1.2 Ohms
Secondary Coil 13,000 ? 20,500 Ohms
Condenser .35 MFD +/- 10%
Excited for KOSH,
See you there
Thomas S.
Thanks guys,
I have a starting point at least, When we put the mag in there was a "minor" discussion regarding it being 180 degrees out, so out it came and double checked but if we double checked it wrong wellllll, at least one was right
I'll check for spark today if I can get past the kitchen guard When you're only home two days a week both days at the airport need special permission!
I have a starting point at least, When we put the mag in there was a "minor" discussion regarding it being 180 degrees out, so out it came and double checked but if we double checked it wrong wellllll, at least one was right
I'll check for spark today if I can get past the kitchen guard
When you're only home two days a week both days at the airport need special permission!7DeltaLima
Well Known Member
pulling wedges
Jim,
I used an open end wrench... or about a 6" adjustable wrench would work to fit up under the lip of the wedge. I also used the head of an eye bolt, cut to fit up under the lip of the wedge on the other side. It took a pretty decent lick with a hammer on the wrench to get the wedge to move.
If you're pulling the coil, I'd consider it consumable if you need a place to rest the wrench to pry.
One more self confession. I broke the lip of one of the wedges when pulling it out. Thought for sure it was time to buy a new mag. ..... the wedge itself is made of "pot metal" so is very easy to drill out (at least in my extensive coil replacement experience of 1 ).
Doug
Jim,
I used an open end wrench... or about a 6" adjustable wrench would work to fit up under the lip of the wedge. I also used the head of an eye bolt, cut to fit up under the lip of the wedge on the other side. It took a pretty decent lick with a hammer on the wrench to get the wedge to move.
If you're pulling the coil, I'd consider it consumable if you need a place to rest the wrench to pry.
One more self confession. I broke the lip of one of the wedges when pulling it out. Thought for sure it was time to buy a new mag. ..... the wedge itself is made of "pot metal" so is very easy to drill out (at least in my extensive coil replacement experience of 1
). Doug
Jim P
Well Known Member
Thanks Doug, I've pulled those wedges when doing the Mag SB on my left mag, and broke off the head for both of those wedges, then ended up drilling them out! What a pain in the rear, that's why I was asking if there was an easier way when I have to do another one day!. By the time I was done investing in a coil and new distributor gear, I could have bought a new mag!
G3i Ignition
Well Known Member
When the coil needs to be removed and the wedges are stuck. Take a flat tip screwdriver and work the coil wedge back and forth laterally. This can aide in removal before prying/pulling the wedge up and out.
Thomas S.
Well all is working fine now. I pulled the mag and started from scratch. The internal timing was OK, I thought I may have put the gear 180 out but with the timing pin inserted the marks lined up perfectly. Installed a new brush since I had one and it was one of the parts that may have been bad. It did continuity check OK though. The one thing for sure was the point gap timing was off. I had installed a new cam as part of the AD and checked the points for condition but I DIDN'T verify that they opened/closed at the correct time. Seems the new cam was slightly larger than the original, wear maybe? (the cam was coming apart prematurely which is what generated the AD) and caused the point to open way too soon, about an 1/8" turn of the rotor off. Set the point gap, reinstalled the mag, timed both back up and fire'd her up. The engine started better than it ever had, almost surprised me how fast it kicked off...The engine now starts and especially idles better than ever.
