Slick Magneto problem on an O-360

After 430 tach hours on my RV, my left Slick mag stopped working in flight. The rite mag got me safely back to the airport. My Slicks were new 430 hours ago and came with my new Superior O-360.

Today, I ohm-ed the key switch to check for faulty grounds. Key switch checked OK.

I removed the ground wires from both mags, and also disconnected the leads from the Dynon 180, and attached my trusty buzz box which tells me when the points open. Buzz box buzzed like it did when I did the conditional inspection in Dec. Timing was OK.

I removed one spark plug that's connected to the left mag and one from the rite mag and grounded both to the engine so I could observe them. A friend spun the engine with the starter and both plugs fired. The spark was not impressive but definitely sparked. My spark plug cleaner displayed a much more prominent spark. I didn't try to start the engine, but my guess is it would have started. I am waiting for the batt to recharge.

Ok folks, what's wrong? Comments and guesses are welcome. Given how close the mags are to 500 hours, it's time for a rebuild but I would like to solve the problem.

Thanks.

Coil or condenser---Hope it is the condenser $$$!

Cheers,

db

carbon brush/cam ?

My slick 4370,4371 mags are of approx. the same age (450 hrs) and as I recall I had to pull one of them back at approx. 100 hrs due to a service bulletin on the carbon brush and cam. Seems Unison got some bad OEM parts back about the time your mags were new/rebuilt (if you fly 75-100 hrs/ year as I do)

You might check the serial number on the mag and see if it was subject to the SB that perhaps got missed. Here is a link to the link so to speak.
http://www.vansairforce.com/community/showthread.php?t=31100&highlight=slick

Only my left mag fell within the serial numbers of the SB and was fixed so I didn't address the right mag. Engine has run great to date (knock on wood) Areosport O-320.

Will also do the 500 hr inspection coming up shortly and am curious to inspect the carbon brush and cam especially off of the right mag. which wasn't subject to the SB but it was very very close.

I would be very interested to know what you find out as it seems yours and my mags seem to be at the same wear.


doug

mag

I had my right mag work fine on run up and initial flight but shut down after a stop. Decided it would get heat soaked upon engine shutdown and the coil would quit. With 500 hour OH plus cost of new coil decided to replace from Spruce and only be grounded for two days instead of weeks.

I had the same thing happen to me a few weeks ago. I called some local guys at a place called QAA. They helped me troubleshoot the 4330 mags, and said I could drop them off/send them in at any time if I wanted them looked at. Their number is 877-833-6948
Mark and Justin were great. Hopefully they can help you troubleshoot your mags too Barry!

Thanks - waiting for parts

We opened both mags and disassembled them under the watchful eyes of someone more experienced than me. We also had a local A&P look at them. It appears the points were arcing and the gap was too small. The coils were not fully saturated resulting in little, to no spark. I confirmed the limited spark by observing the flash generated across the gap of the spark plug. It's hardly a great test, but the spark size looked very small to me. They were much smaller than the spark the plug cleaner generates.

We "ohmed" the coil, inspected the impulse coupler, everything else looked good, so I ordered points and condensers for both mags.

Chief had the best price. Parts will arrive in a few days.

I've worked on mags before but each time I am reminded how incredibly primitive these systems are. It's the exact same system as the 57 Nomad I restored. Nevertheless, it works. I had 420 hours of good performance & my guess is the performance will be better with the gap size corrected.

Home built tool to set Slick mags

Sorry for the time lapse, but here is a photo of a tool we welded to help us set SLICK points. Using a borrowed Slick tool, we lined this up and welded it.

We replaced the points and condensor in both mags and 72 hours later, still working great. Hope this helps.