Magneto Problem??... HELP!! :(

F

flygirl34q

Ejection Handle Pulled
Joined
May 8, 2010
Messages
833
Display Name
Display name:
-
I have been having a lot of trouble with hot starts lately, although cold starts (first flight of the day) are easy. So, I took my airplane into my mechanic, thinking he could provide me a quick and easy fix, and now he tells me that I need a new left magneto. (Another one of his theories is that my carburator needs an overhaul.) He even sent me a couple of photos:

100_4627e.jpg


100_4625e.jpg


I don't know what a normal one looks like, so that is why I am here. Does this magneto need replaced?? My airplane is a '77 Piper Archer II and the engine is a Lycoming O-360. It has about 1,400 hours SMOH. Thanks for your help.... I could really use it. I get the feeling that he is throwing parts at my problem here without really knowing what that problem is! :(
 
It does need a distributor block for sure. looks very typical for a 1400 hour mag.
but was probably still working when he pulled it, but now that you know it is in need, it must be dealt with.
 
If your mags have more than 500 hours on them, you're on borrowed time and I'd personally pull them both and replace with new. They won't fail when you're sitting in front of your home base mechanic. And if one has failed, the other one's probably not far behind.
 
jdangel said:
I just had mine inspected by Andy Richards (http://www.themagnetoshop.com) and was very happy with the results.

Reasonable to ship there, and they will be in great shape when you get them back.

Jeff
Click to expand...

Buy a new set, this one lasted 1400 Hours, and has yet to be proven that it was the problem.

what we don't know

1. what the plugs looked like.
2. what the timing was
3. If the primer system was working,
4 what fuel he was using.
5 age of the engine
6 does it have an induction leak?

and the list goes on

Let's just shoot the parts gun at it until the expense is equal to the problem, and hope it goes away.
 
Our mags have a 500hr inspection. I'm not sure if that's mandatory or recommended and whether or not it's for all magnetos. We do them.

Tom - do you recommend disassembly and inspection at regular intervals or only when problems arise?

Joe
 
Tom-D said:
IMHO that's BS
Click to expand...

In my experience owning several aircraft over the last 11 years, that's reality. And, of the 6 aircraft I've owned, all were either new or had less than 250 hours on them when I bought them. All aircraft were hangared and spent less than a couple of days outdoors in their life with me. All aircraft have been flown regularly with annual times between 60 and 450 hours.
 
500 hours on mags? That's stupid, or poor design. There's no excuse for mags to underlast an engine.
 
I am a believer in the 500 hour inspection for the Bendix mags. I am told that with Slick mags it makes more sense to replace than repair.
After the in flight failure of my D3000 Bendix duplex mag, I replaced it with an overhauled unit from Kelly Aerospace. At its 500 hour inspection the distribution block was found to have a crack in it.
Mags are generally rugged, time proven components, BUT we really need them to run. Manufacturers' strongly recommended inspections should not be ignored, and are definitely not BS.
 
A point to consider is that an IRAN (inspect, replace as necessary) is not the same as a timed out part.

What Tom responded to was that mags are no good after 500hrs. What I want to know is how someone I respect (Tom) maintains his magnetos.
 
SkyHog said:
500 hours on mags? That's stupid, or poor design. There's no excuse for mags to underlast an engine.
Click to expand...

It's also stupid that the entire world spends a significant share of it's productivity defending ourselves from each other. So let's not spend any money on defense and just get along?

It might be stupid but you ignore the reality of it to your own peril. I guess a question for those that think this is BS - have you owned many mags that you put more than 500 hours on? A few will last a while but there's definitely a hockey stick curve that starts around 500 hours.
 
PittsDriver said:
If your mags have more than 500 hours on them, you're on borrowed time and I'd personally pull them both and replace with new. They won't fail when you're sitting in front of your home base mechanic. And if one has failed, the other one's probably not far behind.
Click to expand...

I've never had a mag failure and I've run several (like a dozen or more) for 1500-2000 hours between overhauls and/or replacements. It is strongly recommended that they be inspected (opened up) every 500 hours and occasionally I've found it necessary to replace a few parts then but replacing good mags every 500 hours seems like serious overkill to me.
 
SkyHog said:
500 hours on mags? That's stupid, or poor design. There's no excuse for mags to underlast an engine.
Click to expand...

AMEN ! I have over 50 years in the industry both military and civil, the mags pictured above are typical of the 1400 hours time in them. most mags will go to TBO of the engine, with out even a point change, this is a case of 2% of the mags making 100% the news.

any mag with over 500 hours usage, when opened will show wear, and electrolysis erosion on the distributor block, that does not mean it will fail any time soon.
 
Areeda said:
A point to consider is that an IRAN (inspect, repair as necessary) is not the same as a timed out part.

What Tom responded to was that mags are no good after 500hrs. What I want to know is how someone I respect (Tom) maintains his magnetos.
Click to expand...

I put new om at over haul, and repair/replace when needed.

the most common failure in a bendix or slick mag is the plastic gears, the recommended 500 hour inspection does not require those be changed.

new mags will have new gears installed.
 
Areeda said:
Our mags have a 500hr inspection. I'm not sure if that's mandatory or recommended and whether or not it's for all magnetos. We do them.

Tom - do you recommend disassembly and inspection at regular intervals or only when problems arise?

Joe
Click to expand...

I repair as required, If you have a high mag drop, trouble shoot it, find out why, and fix it, 99 times out a hundred it will not be the mag.

If it is, I base my recommendation upon my experience, and buy new if I think the repair parts will equal 50% of a new mag.
 
flygirl34q said:
I have been having a lot of trouble with hot starts lately, although cold starts (first flight of the day) are easy. So, I took my airplane into my mechanic, thinking he could provide me a quick and easy fix, and now he tells me that I need a new left magneto. (Another one of his theories is that my carburator needs an overhaul.) He even sent me a couple of photos:

100_4627e.jpg


100_4625e.jpg


I don't know what a normal one looks like, so that is why I am here. Does this magneto need replaced?? My airplane is a '77 Piper Archer II and the engine is a Lycoming O-360. It has about 1,400 hours SMOH. Thanks for your help.... I could really use it. I get the feeling that he is throwing parts at my problem here without really knowing what that problem is! :(
Click to expand...

I see little wrong that can't be fixed with a cleaning and maybe new points. Your mechanic should have provided a picture of the point contact surfaces, which are hard to photograph. At 1400 hours the points will be shot. The rotor's carbon brush is also going to be worn pretty bad. Again, no picture. The condenser should be checked for capacitance.

Points are around $30. The brush, $8. Labor shouldn't be that bad. New mag is around $900 and still has to be installed and timed.

Dan
 
jdangel said:
I just had mine inspected by Andy Richards (http://www.themagnetoshop.com) and was very happy with the results.

Reasonable to ship there, and they will be in great shape when you get them back.

Jeff
Click to expand...
Andy is THE MAN when it comes to Mags. I sent mine to him for inspections and repair. Came back looking and acting like new.
 
NC Pilot said:
Andy is THE MAN when it comes to Mags. I sent mine to him for inspections and repair. Came back looking and acting like new.
Click to expand...

If you don't mind saying, what kind of mag was it and what did this service cost?
 
PittsDriver said:
If you don't mind saying, what kind of mag was it and what did this service cost?
Click to expand...
Dual mag on a Cessna R182. Can't remember the cost, but it was very reasonable. p/n BL-682560-11
 
PittsDriver said:
If you don't mind saying, what kind of mag was it and what did this service cost?
Click to expand...

Depends obviously on what you need once the inspection happens, but for both of my Bendix mags it came out to $800 total. We changed the capacitors which was a choice I made, it would have been less without.

Jeff
 
jdangel said:
Depends obviously on what you need once the inspection happens, but for both of my Bendix mags it came out to $800 total. We changed the capacitors which was a choice I made, it would have been less without.

Jeff
Click to expand...

punch this (08-02897 SLICK KIT K6565U-40 BLUE) into the search window at

http://www.aircraftspruce.com/menus/ep/ignition_0slickkits.html


and see what 2 NEW slick mags and 2 new harness, and 8 new spark plugs would have cost you.
 
jdangel said:
Apparently I am missing something. Sure, new slick mags cost $1800 with the new plugs. I spent $800 total for both mags. Not worth an extra $1,000 to me for new.
Click to expand...

I missed the part about both mags, 400 each, isn't that bad.
 
Tom-D said:
one of these kits should fix the mag problem........
http://www.aircraftspruce.com/catalog/eppages/slick5.php...
Click to expand...

The link seems to make a fairly significant point of the color of the wiring harness, red, blue, yellow, black, and that they only stock the blue harnesses.
:confused:
What difference does the color of the wire covering/insulation make? Why would I want a yellow harness instead of a red harness, for instance?
 
Tom Veatch said:
The link seems to make a fairly significant point of the color of the wiring harness, red, blue, yellow, black, and that they only stock the blue harnesses.
:confused:
What difference does the color of the wire covering/insulation make? Why would I want a yellow harness instead of a red harness, for instance?
Click to expand...

For pure awesomeness. I am replacing both harnesses at this year's annual, and I'm going with red to match the trim color. Will anyone see it? Not likely, but I will whenever I pull the cowl to look for leaks, birds, or just to look at my red ignition wires.

Edit: Hi Tom. Welcome.
 
What... no PURPLE wiring harnesses?? I normally would be all over something like that, but I have had nothing but mechanical problems with my airplane since I have gotten back from a certain fishing resort in Arkansas and it SUCKS. :incazzato: Today, I had the engine completely quit on me during the process of landing at an airport to pick up some friends for a weekend trip to Door County in Wisconsin... and as a result, we ended up driving there instead. :confused: F my life.
 
flygirl34q said:
What... no PURPLE wiring harnesses?? I normally would be all over something like that, but I have had nothing but mechanical problems with my airplane since I have gotten back from a certain fishing resort in Arkansas and it SUCKS. :incazzato: Today, I had the engine completely quit on me during the process of landing at an airport to pick up some friends for a weekend trip to Door County in Wisconsin... and as a result, we ended up driving there instead. :confused: F my life.
Click to expand...
It's because I was in your airplane. The boost pump in Felix's rental died when I sat in it. Ted's left engine wouldn't start once I climbed in.

Spike - what did I break in your airplane?
 
I can't confirm that the cause of the issue is Jesse, as I've never had him in my airplane.

However, I think maybe "The South" is to blame for your problems. We went down to Texas (Port A) and had a magneto die on us. We got stuck in Amarillo for 2 nights waiting to get it rebuilt. Also the humidity made the throttle and prop controls rust up.
 
Well, I am in the proactive / preventative maintenance camp...
Good plugs, good wires, and well maintained magnetos make for for a happy pilot...

I watch one plane after another sitting on the ramp cranking and cranking trying to start... If it was your car it would be back to the dealer time, yet they want to leave the ground behind an engine that can barely be started only after cooking the starter, killing the battery, and exhausting the pilot's supply of swear words...

Fat Albert starts on the second blade, cold, hot, or in between... I am a happy pilot... Money well spent...

And Jesse, I was thinking if inviting for a ride, but after you point out your record - forget it!

denny-o
 
I can, in fact, attest to Jesse being a cause of most mechanical failures. However, I'd still take him in my plane anytime.
 
Dr. O said:
Well, I am in the proactive / preventative maintenance camp...
Good plugs, good wires, and well maintained magnetos make for for a happy pilot...

I watch one plane after another sitting on the ramp cranking and cranking trying to start... If it was your car it would be back to the dealer time, yet they want to leave the ground behind an engine that can barely be started only after cooking the starter, killing the battery, and exhausting the pilot's supply of swear words...

Fat Albert starts on the second blade, cold, hot, or in between... I am a happy pilot... Money well spent...

And Jesse, I was thinking if inviting for a ride, but after you point out your record - forget it!

denny-o
Click to expand...


NOW you guys tell me... Jesse is a jinx. :(

As long as I kept the power over 1350 RPM's or so, I could keep it going and I sat on the ramp for a minute or so contemplating the wisdom of taking my friends just 120 short miles to our destination and save us all a long drive, but I couldn't do it. :( (It was kinda like being Bob Hoover on short final, rollout, and then coasting to a stop at a convenient intersection and the restarting... you know when he used to do his energy management routine??) :hairraise: But, I still couldn't do it and I think I did the right thing. Hopefully, I will get a call from the mechanics helping me today or tomorrow and I will know more about what my options are. :incazzato:
 
flygirl34q said:
NOW you guys tell me... Jesse is a jinx. :(

As long as I kept the power over 1350 RPM's or so, I could keep it going and I sat on the ramp for a minute or so contemplating the wisdom of taking my friends just 120 short miles to our destination and save us all a long drive, but I couldn't do it. :( (It was kinda like being Bob Hoover on short final, rollout, and then coasting to a stop at a convenient intersection and the restarting... you know when he used to do his energy management routine??) :hairraise: But, I still couldn't do it and I think I did the right thing. Hopefully, I will get a call from the mechanics helping me today or tomorrow and I will know more about what my options are. :incazzato:
Click to expand...
Whenever an airplane does something funny and you're not sure why. It's never a bad idea to stay on the ground. Sounds like good judgment at work to me.
 
flygirl34q said:
NOW you guys tell me... Jesse is a jinx. :(

As long as I kept the power over 1350 RPM's or so, I could keep it going and I sat on the ramp for a minute or so contemplating the wisdom of taking my friends just 120 short miles to our destination and save us all a long drive, but I couldn't do it.
Click to expand...



That sounds more like a plugged idle circuit in the carb, or an induction leak. Non-electrical for once, maybe...

Dan
 
Last edited:
OK, I have a similar problem with my Cessna 172, lycoming 0320 engine. My engine runs fine at the higher rpms but when we bring it back to idle it sporatically backfires. I had the old disposable mags on it when I bought the airplane and it ran fine. I bought used mags from wentworth [4370&4200 series] and had them rebuilt here locally and that is about when my backfiring , or popping started. Got and ideas??
Thanks,
Tom
 
jesse said:
It's because I was in your airplane. The boost pump in Felix's rental died when I sat in it. Ted's left engine wouldn't start once I climbed in.

Spike - what did I break in your airplane?
Click to expand...

Nothing that I know of, Jesse, but thanks for trying. :wink2:

The CHT sensor on No. 2 quit last week, and when I went to replace it, the Tanis heater probe (which must be removed to replace the CHT sensor) broke in two, clearly overtorqued when it was installed in the first place.

Don't think I can lay that on your plate, Jesse.
 
90% probablity - induction air leak causing one or more cylinders to run excessively lean at low throttle settings

10% probability - fuel line leak upstream of engine driven fuel pump drawing air into the line, possibly at the gascolator gasket, causing similar symptoms

Thomas said:
OK, I have a similar problem with my Cessna 172, lycoming 0320 engine. My engine runs fine at the higher rpms but when we bring it back to idle it sporatically backfires. I had the old disposable mags on it when I bought the airplane and it ran fine. I bought used mags from wentworth [4370&4200 series] and had them rebuilt here locally and that is about when my backfiring , or popping started. Got and ideas??
Thanks,
Tom
Click to expand...
 
Well, after a run of issues here in Hangar #8, I went flying today and gave my airplane (and me!) a workout and it seems like all is hanging in there for now. I had the airport to myself this morning and after a few ordinary patterns and normal landings with everything looking and sounding as it should, I turned up my IPod all the way and had fun with turning midfield short approaches and doing spot landings Oshkosh-style! KTIP has a 9/27 just like KOSH... all I needed to do was imagine the gravel pit on the northwest side, Lake Winnebago off the east end, and the colored dots and I was so there! :thumbsup: Hopefully, we both are ready for the big show... I know I am ready to have some FUN with my airplane for a change instead of shuttling back and forth between airport maintenance hangars and getting bills from mechanics. :cryin:
 
Steve said:
10% probability - fuel line leak upstream of engine driven fuel pump drawing air into the line, possibly at the gascolator gasket, causing similar symptoms
Click to expand...

An O-320 powered Cessna 172 doesn't have an engine-driven fuel pump. The system is gravity-fed.

Dan
 
You must log in or register to reply here.
Back
Top