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Mag reinstall questions/issues?

RickWoodall

Well Known Member
Looking for tips/help

Had a "mechanic" take out my slick mag and i shipped it away for 500hr inspection. This is outside my area of expertise...wanted it done properly, happy to pay the bill.
Got it back and had the same mechanic set up to reinstall the slick (other side is lightspeed ei) today.

1. 5 HOURS later...no joy
2. First attempt, he didnt know which way it went, forgot, so I had to dig out a pic of the engine so we could see.
3. Then, didn't mount right, and he commented...oh ****, some of the old gasket is stuck on there. (he forgot to clean it off)
4. Then a lot of swearing and issues...couldnt get it lined up. Didnt have tool to lock it so used a small allen key that kind of fit with some wiggle...
5. Didnt seem to line up so decided that inspection place messed it up (really?) and it was really off 180 degrees. So off it came and he toyed with it, but couldnt find a hole to get to lock with allen key at the 180 degree point so no idea there.
6. Then couldnt get it line up so said he took allen key out and just freestyled it (turned) until the buzz box told him lined up and pushed it in, tightened it up
Finally after no kidding 5 hours.... said it was good, timed dead nuts at 25 degrees. Should be perfect.
Yaaaa, finally.... Took it out, started fine and when I did a mag check, the engine DIED on just the mag. I shut it off, got mad and that is where i am at. Told him we need to take a day off...leave it.

This is crazy. How long does it take to install a mag on a io320 with the cowls all off, and if something is not done right this is a BIG deal no?? This should be a 45 minute install no?

Anyway, very frustrated and less then impressed with the installer. He is a good guy and works on lots of planes....but seems lost on a mag install. How can this be?

Any tips or warnings or suggestions? I will ponder it for a day or two and likely hire another person to install. Not getting the warm and fuzzies about this. Of course it was a beautiful fly day. Grrrrr.....
 
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Mag

Magneto install is A&P 101 ! Any one with a " You Tube Diploma " could do it .
Find a new mechanic before this guy ruins something or worse yet kills you .
 
Looking for tips/help

Had a "mechanic" take out my slick mag and i shipped it away for 500hr inspection. This is outside my area of expertise...wanted it done properly, happy to pay the bill.
Got it back and had the same mechanic set up to reinstall the slick (other side is lightspeed ei) today.

1. 5 HOURS later...no joy
2. First attempt, he didnt know which way it went, forgot, so I had to dig out a pic of the engine so we could see.
3. Then, didn't mount right, and he commented...oh ****, some of the old gasket is stuck on there. (he forgot to clean it off)

Indications of sloppy skills and workmanship...as further evidenced by...

4. Then a lot of swearing and issues...couldnt get it lined up. Didnt have tool to lock it so used a small allen key that kind of fit with some wiggle...

You should have stopped right there and gotten someone else to do it...no excuse for a "mechanic" to be jerry-rigging an alignment pin that "kind of fits" here (doing it wrong, as I understand it, can bust internal parts, but regardless...seriously? An Allen key???)

5. Didnt seem to line up so decided that inspection place messed it up (really?) and it was really off 180 degrees. So off it came and he toyed with it, but couldnt find a hole to get to lock with allen key at the 180 degree point so no idea there.
6. Then couldnt get it line up so said he took allen key out and just freestyled it (turned) until the buzz box told him lined up and pushed it in, tightened it up
Finally after no kidding 5 hours.... said it was good, timed dead nuts at 25 degrees. Should be perfect.
Yaaaa, finally.... Took it out, started fine and when I did a mag check, the engine DIED on just the mag. I shut it off, got mad and that is where i am at. Told him we need to take a day off...leave it.

This is crazy. How long does it take to install a mag on a io320 with the cowls all off, and if something is not done right this is a BIG deal no?? This should be a 45 minute install no?

Anyway, very frustrated and less then impressed with the installer. He is a good guy and works on lots of planes....but seems lost on a mag install. How can this be?

Any tips or warnings or suggestions? I will ponder it for a day or two and likely hire another person to install. Not getting the warm and fuzzies about this. Of course it was a beautiful fly day. Grrrrr.....

I don't know if that mag now needs to be taken apart and inspected, but I would a) make sure I got my money back from this guy, b) find another *actual* mechanic to show you how it's done (then you'll never need to rely on anyone else), and c) NOT TOUCH THE PROP as who knows if he's messed up the wiring and left you with a hot mag.

Sorry for your problems...yes, this should have been about a 45 minute job and it's pretty basic.
 
I agree

I do appreciate the feedback.

I agree this is the most basic of plane work. I was just beside myself today and trying to politely say BACK AWAY and stop fing with the plane!

I am so angry, frustrated and disappointed. Posting here is just venting.

Thanks for the comments, they are reassuring me of the fact this has gone WAY off the tracks and not ok or allowable on my airplane.
 
Mag install

Mag install and timing is not too complicated . Search ( Google /Yahoo ) for magneto install . Try to find a knowledgable person to walk you thru the process . After a few installs it no more time consuming or complicated than changing your oil .
Also I check my mag timing at every oil change , takes only minutes.
 
Mag

1. Fire the pretend mechanic
2. Don't pay him anything
3. Find a real mechanic or educate yourself on how to do it. The important thing is whether or not this is an impulse mag. If it is impulse you must snap the impulse and then rotate the gear in the opposite direction to locate the pin hole.
If you hold the mag in your left hand, looking at the gear, turning the gear counter clock wise is the normal direction of rotation for a Lycoming.
The entire process:
Remove all top spark plugs
Doing a finger check for compression on cylinder #1, rotate the prop until you have compression on cyl 1. Rotate the prop further to verify the top dead center mark on the ring gear in line with the split of the crankcase at top.
Back up the prop past the 25 degree mark, then forward to the mark.
You are now positioned to install the mag with the pin in the hole.
I will not go into the fine tuning, you need a mag timing box for that, but basically you are moving the mag slightly back and forth to set the timing exactly on the 25 mark.
Another option if you have an impulse is to slowly rotate the gear clockwise until the pin drops in. IIRC the pin will only drop in when the mag is positioned to fire the #1 cylinder, so that part is easy. This bypasses the impulse, the impulse only engages when the gear is turned counter clockwise. If you don't know what the impulse looks like, if you have a spacer about 3/4" long between the accessory case and the magneto, you have an impulse, no spacer no impulse.
 
Mag install is pretty simple. The allen key instead of the actual timing pin isn't great, but really close enough that the engine would probably run fine.

I didn't see if this was the left mag with an impulse coupling or not, but that, while simple to deal with, can often throw a curve at someone who isn't on top of what he's doing.

At this point, I'd suggest another A&P (who has experience fixing mags). For me, especially if this mag has an impulse coupling, I'd want a good mechanic to look it over (exterior inspection) to be sure nothing has been damaged in the failed attempt to get this installed. (For example, the last thing you want is pieces of the impulse coupling falling into the accessory case - as in you'll be looking for somewhere to land.)

A good A&P can easily show you the basics of getting a mag on and off, timing and should be willing to do that.

PS - there is some possibility that timing marks on the starter ring gear are not correctly oriented. All it would take is someone removing the it to - say change a belt / change a prop / etc. - and not repositioning it correctly. Someone who understands mag timing can do some diagnosis and easily figure out the correct positions and the sharpie makes a good temporary solution (I've run into this a couple of times).

Dan
 
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Info

It is a slick mag...impulse.... and left side. Right is lightspeed plasma 2 EI.

Ugghhh......

Bottle of wine is helping but still pacing back and forth trying to relax.....whole saturday killed and plane not back together.

mmmmm, more wine ....:eek: Switchng to shots soon. That should fix something....
 
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Rick - you've had lots of good info provided above. JRS's post gives you the vital essence of the operation. It is NOT rocket science, but it does take some finesse, and a basic understanding. When in doubt, do a search on the internet for Slick's installation instructions - I know I found them and they were indispensable.

One item not mentioned is that, even if you seem to do everything right, it is possible to get one gear tooth off proper alignment. If this happens, you will be able to 'almost' get the mag to time to 25 degrees, but not quite. The solution is simple... lock the mag again with the pin, remove it so you are just barely clear of gear engagement, rotate the mag slightly, reattach and then try the timing again. The last time I pulled mags on an O-320 this happened and for the life of me I still can't figure out why.

As for an AME that doesn't know how to install mags, it is very conceivable that he has no piston engine experience, or at least not current experience. I know in my case all of my experience was with turbines - I could change an igniter or a bleed valve on a R-R 250-C20 with my eyes closed, but when I started playing with piston engines again, I had to hit the books. There is absolutely no way you should be paying him to learn. One of the basic tenets of the Canadian AME licensing system is that we have to know what we are qualified to work on, and if we are not qualified, we our license privileges are invalid. This guy clearly is not qualified, so at a minimum, he has violated the CARs in that regard. If he gives you a hard time about billing, don't be shy to trot this out as a technique to bring him back to reasonableness.
 
Find another mechanic, I just RR'd 2 mags for a customer for a 500 hr check yesterday, I charged 2 hrs labor for the whole job (RV8 has easy access and cowls already off).
 
....
PS - there is some possibility that timing marks on the starter ring gear are not correctly oriented. All it would take is someone removing the it to - say change a belt / change a prop / etc. - and not repositioning it correctly. .....
Dan

Isn't one of the drive lugs slightly oversize and one of the six holes slightly larger to prevent this happening?
 
Isn't one of the drive lugs slightly oversize and one of the six holes slightly larger to prevent this happening?

That is correct.

I agree with others. Time for a new mechanic. It only took me an hour or two to install both mags and time them. It can be challenging to get the pin to drop into the inner gear and I am guessing he either has five thumbs or was very impatient.
 
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I recently fitted my own mags having never done it before or ever worked with mags. A bit of interweb research and asking some questions around gave me all the info I needed. The only proviso is that my left mag had a retard breaker, not an impulse coupler.

Here's a summary:

- Put the number 1 cylinder at 25 BTDC. Make sure it's on the compression stroke.

- The mag now needs to be locked in it's No1 firing position - hence the pin. This is just to make sure you have the correct cylinders firing in sequence and only a rough adjustment. If you can get a proper lock pin, so much the better. If not, you can use the blunt end of a 3/32" drill. The line-up hole will only be in position on every fourth turn of the mag. As you turn, you can feel the dead band. By careful inspection with a torch, you can see the hole line up. My mags had two holes for left or right rotation, so beware. IMPORTANT. The pin must drop in easily - DO NOT FORCE IT or turn the mag in an attempt to line it up. If you feel any resistance STOP as you can damage internal components.

- Mount the mag. It is now approximately timed.

- Use the buzz box to accurately time it.

That's the basics but there may be other steps to check the impulse timing.

Even with a bit of head scratching, the whole process for two mags only took me a couple of hours.
 
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Mags

I pull one set of spark plugs for safety any time I am working on the mags.
This also makes the finger check to determine top dead center easy. At approximately top dead center on cylinder #1, check that the ring gear top dead center mark lines up with the upper crankcase split. If it lines up you have now determined that the ring gear is properly positioned.
With the timing pin the Slicks are relatively easy. Try to get the gears to engage with the accessory case studs approximately in the center of the mag attach slots. This is not always possible but it will allow the maximum adjustment with the buzz box.
After fine tuning with the buzz box, back the prop up a few degrees and then slowly tap the prop forward towards the 25 degree mark. You are making a final verification that the mag is firing at exactly at the 25 degree mark.
 
Which versions don't comply?

I'm wondering if we're possibly talking about two different things. I think you're talking about the flange on the crankshaft for the propeller - the prop should indeed mount only one way if the service bulletin is followed. However, some earlier older engines I've seen (I can't quote you the specifics other than to say they were all O-320s) could have the prop installed in several positions.

What I'm referring to is the starter ring gear support that fits over the bushings in the prop flange before mounting the prop (ie., it sits between the prop and the crankshaft flange). That ring gear support can be mounted in several different positions. All I can say is that I have seen this installed incorrectly a couple of times. When this happens, properly timed, the engine runs just fine. However, when the position is incorrect, subsequently relying on timing marks on the ring gear support can lead to some serious mis-timing.

Dan
 
I'm wondering if we're possibly talking about two different things. I think you're talking about the flange on the crankshaft for the propeller - the prop should indeed mount only one way if the service bulletin is followed. However, some earlier older engines I've seen (I can't quote you the specifics other than to say they were all O-320s) could have the prop installed in several positions.

What I'm referring to is the starter ring gear support that fits over the bushings in the prop flange before mounting the prop (ie., it sits between the prop and the crankshaft flange). That ring gear support can be mounted in several different positions. All I can say is that I have seen this installed incorrectly a couple of times. When this happens, properly timed, the engine runs just fine. However, when the position is incorrect, subsequently relying on timing marks on the ring gear support can lead to some serious mis-timing.

Dan

Dan,
I am in agreement with Gil, and neither of us appear to be confusing clocking a prop vs correct indexing of the starter ring adapter. Could you please reference the O-320 parts manual that illustrates what you are referring to? Additionally, my O-320 Overhaul Manual specifically refers to indexing of the gear on the larger diameter lug.
Preparing to learn something! Thanks!
 
I have to agree with Dan here. Even though the manual clearly shows 1 "index" bushing, I too have run across more than one O-320 without this indexing bushing and where the flywheel was installed improperly.
 
When paul refers to a "torch", he is talking about a flashlight.
Good clarification, also don't forget to remove the pin from the mag before proceeding with the final adjustments by moving the prop, it can be a costly mishap

Good luck not that you need it
 
The Lycoming SI states that an indexing bushing is present on all configurations.

This bushing is about 0.030 inch larger in diameter, and marked with a solid square symbol on the list -

http://www.lycoming.com/Portals/0/t...8-2012)/Propeller Flange Bushing Location.pdf

Which versions don't comply?

One that has been modified in the field, not documented, and isn't in compliance. I had one like that on my Yankee after I upsized the engine - and I wasn't knowledgeable to know that it wasn't right. Got the flywheel on wrong one time, and it took some head scratching to figure out why we couldn't get it timed right!

Bottom line is to assume nothing - espcially in the re-built, experiemntal engine world. Strange things happen when people change prop bolt bushings and modify engines.
 
One that has been modified in the field, not documented, and isn't in compliance. I had one like that on my Yankee after I upsized the engine - and I wasn't knowledgeable to know that it wasn't right. Got the flywheel on wrong one time, and it took some head scratching to figure out why we couldn't get it timed right!

Bottom line is to assume nothing - espcially in the re-built, experiemntal engine world. Strange things happen when people change prop bolt bushings and modify engines.

The two stamped "O" marks on the prop flange face and the flywheel should be a big hint though....:)
 
When paul refers to a "torch", he is talking about a flashlight.

Actually, I'm talking about a torch. You ex-colonialists can call it what you want......

And as a later post mentioned, take out the pin once the mag is mounted - sorry, forgot to say that.

Honestly, I was surprised at how easy the whole thing was.
 
Most Slick Mags have two timing holes in the back of the distributor block, RH and LH, which represent the two possible directions it can be run. Lycomings are LH turning (If I recall correctly / consult the manual). I have seen folks try to time the left mag to the LH timing hole and the right mag to the RH timing hole. Both should be to the same LH hole. The crankshaft should have one prop flange dowel lug with an "O" on it. The starter ring gear should have a corresponding "O" that will align with the crackshaft "O". The starter should have a dimple on it that is the timing mark to align the ring gear mark. You can use a timing light / buzz box to set the mag at its #1 firing position, if you know ahead of time which direction you are turning the mag and if you have made a mark on the drive and mag housing.....but the timing pin is so much easier.
 
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