Took my 182 up today for an hour or so to get some fuel, during my runup i had a rough left mag, occompanied by a red indicator on my digital tach for the left mag...i agressively leaned it at 2000rpm and all was fine very smooth...upon my fill up in madera i did a mag check prior to departure and had a smooth as glass left mag and a rough right mag, it was hard to clean out but i got it smoothed out and came home...plane goes in for annual march 1st what are your thoughts...

On the ground im leaned out all the time, and i dont sit and idle for days! Am i losing a mag, and is the bad one bringing down the good one with it?? Can that happen?

Thanks

Mike

Mike, I'm betting that you have plug problems.
Ron

thanks ron, i was thinking it could be the same thing, since leaning it out cleans the plugs...it was weird to have the indicator light on for the left mag being out though...i will find out this week in the annual im sure though $$$


mike

Might have a clinker or two in the plugs if you are running 100LL. Worn harnesses can drive you nuts too. I'd bet plugs, though.

+1 for plug issue.

Aircraft Magnet Service of Seattle has a handout entitled "is it the mag?", in it he relates that most "bad mag checks" are sparkplug related. Per this handout: pull the plugs & test the resistance through them with an ohmeter. Stick one probe down inside the barrel & touch the other one to the center electrode. A new plug will read in the neighborhood of 1000 ohms. Anything over 5,000 is no good. Don't trust those "bomb testers", the plug can test good on those & still be out of spec on the resistance. Take my word for it, plugs can look just great with very little erosion on the business end & still be no good (been there, done that). Common wisdom sez to expect about 500 hours out of a set of plugs before they need to be replaced. BTW in my experience a Bendix mag will continue to spark a funky plug long after a Slick will not.
I know a guy who's C172 was running rough, his mechanic told him it was the mags & sent them off for overhaul ($$$). Got them back & installed and guess what-- it still ran bad. Mechanic told him "I guess it needs plugs too" and a new set of plugs later (more $$) it ran just fine. How about that! I already had a rather low opinion of his mechanic & this incident just reinforced that.

Don't know for sure, but have heard some fellas put fine wire plugs on the bottom holes and have fewer problems.

CC