Oil leaking into Bendix SF4RN-8 mag

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jesse

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Jesse
Pulled the mags on the Flybaby and the left mag has a decent amount of engine oil in it. Right does not.

I assume this must be the seal on the shaft on the magneto. Anyone ever replace these before? Something I can do easily without special tools or something I'm better off having someone do?

Picture, notice how the one on the right in the picture (which is actually the left mag) is much darker than the other. That's because it's covered in oil.

VMaORDG.jpg


Full size here:
http://i.imgur.com/6ttaeEV.jpg
 
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Are you sure it is not by design? The stator in my GSXR motor is wet with oil as designed...
 
I've repaired mags before, but that one, I' most likely send out for overhaul. There may be some wear on the shaft that just replacing the seal won't fix.

BTW, where did you find those antiques? :)
 
Yeah, you can do it - but do you want to?
Since you are asking the question you have answered the question.
I grew up in the world of :
see one
do one
teach one

Take it to a mechanic and the two of you replace the seal on this one. I also question if the E gap is correct, and so one. Time for that puppy to have a good going over.
Next one you do.
After that you set up shop :D
 
jesse said:
Pulled the mags on the Flybaby and the left mag has a decent amount of engine oil in it. Right does not.

I assume this must be the seal on the shaft on the magneto. Anyone ever replace these before? Something I can do easily without special tools or something I'm better off having someone do?

Picture, notice how the one on the right in the picture (which is actually the left mag) is much darker than the other. That's because it's covered in oil.

VMaORDG.jpg


Full size here:
http://i.imgur.com/6ttaeEV.jpg
Click to expand...


????

Seal 10-357592 $18.50


Feeling adventurous? I'm pretty sure we can fix that ourselves.

http://www.aircraftspruce.com/catalog/eppages/sf4replace.php


I have a set of Slicks with harness off the cardinal and enough parts to "rebuild" them but that's not cheap, Nor would the impulse lag timing be proper for the Flybaby.

I'm thinking about $50 in parts and your mags run another decade trouble free.
 
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Anyone have any idea where I can get an illustrated parts list for the SF4RN-8? All the manuals I've found and have been sent are missing an exploded parts diagram and part numbers.

I've found a website that sells the parts list online as a PDF download but charges $15, which I'm not about to pay them unless I can help it.
 
Looks like the seal I need is PN 10-8673, now the challenge is to find it or a replacement.

Oil was leaking into the mag because that seal was completely missing.
 
Gasket and seal kit for Bendix SF4 mags available from Fresno Airparts Co
559-237 4863 , info from the full page ad in Trade-a -Plane.
 
biplanebob said:
Gasket and seal kit for Bendix SF4 mags available from Fresno Airparts Co
559-237 4863 , info from the full page ad in Trade-a -Plane.
Click to expand...

Thanks, appreciate it, will give them a call tomorrow.
 
Ordered new gaskets and seals for the Mags, cost like $20. I think that'll get me back up and running again.

I tore down the left mag last night:
fLSN9Pv.jpg


Should be interesting trying to get it back together. I'll have to figure out an accurate way to measure things so I can set the e gap but seems totally doable.
 
No no no! You better send that out to a shop that hasn't seen one in 30 years and pay them a fortune to do it for you.
 
I went through this a few years ago. My mag had so much oil in it the points were under oil. It never quit firing the plugs. You ask how do I know this, this is on an Experimental and only one ignition.

So off comes the mag. As I am holding it I am thinking. How old is this mag? No Idea. I could have just stuck a seal in it and called it good.

This was not going to work on something with one ignition that goes into the air. So I called around looking for a mag company. I had a couple things this company must do or follow before I would order a new mag from them. Seeing how all these mags are rebuilt.

1st. Do they recharge the magnets? 2nd. Do they put mag in a wooden box? 3rd. Do they put this box on a wooden shelf.

I called around and most did not recharge the mags. They would state something like, they are ok no need to recharge they work just fine.

I only found one shop who did what I wanted. I did not ask them do you do this and that. I ask them how they did it. Until I found what I was looking for I would just say, thankyou and hang up. I did this because you have no idea how many shops argued the point of recharging magnets.

There is a reason a mag goes into a wooden box then is put on a wooden shelf. The magnets will get weak if you don't, will it still work? Sure. But the magnets will be weak from day one. Keep that in service another 20 years and see what you have. I know everyone replaces mags before 20 years. Right.

You have two mags and from the looks they have metal gears. On something like this I might do as you and replace the bad parts and call it good. I might send the magnets or case out for recharging though.

My 2 cents for what everyone thinks its worth. Lets see, with inflation, I believe I owe you money.

Tony
 
Jesse,

There is a drawing / print of one in the back of the Bendix Mangeto Overhaul Manual, available for download on Teledyne/Continental website.
tcmlink

The manual # is X42002

print the drawing and glue it to a sheet of aluminum.

A goggle search found an old copy, for current data you need to set up an account log-in to Continental (using you engine S/N)

Bob
 
Do you have the correct magnetos in mind Bob? These are the ANCIENT ones that precede the S20 series.

I don't recall seeing any data in my TCM Master Service Manual for the S4, just S20/S200/S1200/D2000/D3000
 
I was referring to the timing tool. The old manual for the S-20 /S-200 has a paper template for the tool. After searching the new manuals tonight, they only reference the Kellstrom tool. It appears that a common protractor could be used if the arc is mounted the correct distance from the shaft. :)

The timing tool is just an arc from a degree wheel with a pointer and a large price tag.


Bob
 
bnt83 said:
Do you have the correct magnetos in mind Bob? These are the ANCIENT ones that precede the S20 series.

I don't recall seeing any data in my TCM Master Service Manual for the S4, just S20/S200/S1200/D2000/D3000
Click to expand...


I think he's just meaning that there was supposed to be a to scale drawing of the timing tool Jesse is asking for. I looked in the X42002 manual dated August 2011 and I sure don't see it there.

I've got the tool, but I'm not close enough to be of much help unless I mail it out.

EDIT: I see Bob posted again while I was writing mine.
 
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bnt83 said:
Cut up a plastic protractor and a piece of saftey wire and we can probably get by.

Or magnetic digial protractor on the drive gear?
Click to expand...
Or line up the marks in the window, set the gap and be done with it. :eek:

Seriously, the real world the output difference of being a couple of degrees off is hardly measurable. Those mags pack one heck of a punch. Better off spending the time making sure all the connections and contacts are spotless.
 
tyndall said:
Or line up the marks in the window, set the gap and be done with it. :eek:

Seriously, the real world the output difference of being a couple of degrees off is hardly measurable. Those mags pack one heck of a punch. Better off spending the time making sure all the connections and contacts are spotless.
Click to expand...

I know it's not absolutely a critical item. Neither of his mags are equipped with impulse and nor does he have an electric starter tho. A bit of creativity can come up with a solution.

we can go by feel and eyeballs and make it work, but not sure how well that will perform without impulses.
 
Lining up the marks in the window doesn't work when you've torn down every single piece of the entire mag.

Won't be difficult to figure something out.

Next question, the official Bendix mag grease is too rich for my blood at like $60 for a small can. Anything I can use instead?
 
In your picture the cam is still attached to the rotor. If you removed it then yeah, lock wire and a protractor.
 
Aircraft Spruce sells a small tube of grease good for two mags, I think it is a Bosch grease.

Also available from Fresno Air Parts.
 
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Aeroshell 22 would be fine.
 
believe it or now your local case-ih dealer still supports about every part on an old farmall tractor, including the magneto. They'll have the grease and probably some parts that look familiar as well.
 
Jeff, an excellent suggestion as most of those Ancient magnetos had their origins as tractor parts.
 
After researching all of the tractor forums it seems everyone is using synthetic wheel bearing grease in their magnetos and report it works much better than the old "magneto grease".

So...if it works on a tractor..it'll work on a Flybaby...synthetic wheel bearing grease it is.
 
I'm not understanding why you would use a standard moly grease in your magneto.:dunno: Plus I'm not really understanding their use of the term 'synthetic'.

Common Name: SYNPOWER SYNTHETIC GREASE SYNTHETIC GREASE

3. COMPOSITION/INFORMATION ON INGREDIENTS


COMPONENTS CAS-NO. CONCENTRATION

DISTILLATES (PETROLEUM), 64742-54-7 >/=70-<80 %
HYDROTREATED HEAVY PARAF

OLEFIN POLYMER NJTS# 254504001-5128 >/=1.5-<5 %

MOLYBDENUM DISULFIDE 1317-33-5 >/=1.5-<5 %

ZINC C1-C14 68649-42-3 >/=1-<1.5 %
ALKYLDITHIOPHOSPHATE

.
 
No clue. Just going off of what has worked for others. The TCM stuff is over priced.
 
1600vw said:
I went through this a few years ago. My mag had so much oil in it the points were under oil. It never quit firing the plugs. You ask how do I know this, this is on an Experimental and only one ignition.

So off comes the mag. As I am holding it I am thinking. How old is this mag? No Idea. I could have just stuck a seal in it and called it good.

This was not going to work on something with one ignition that goes into the air. So I called around looking for a mag company. I had a couple things this company must do or follow before I would order a new mag from them. Seeing how all these mags are rebuilt.

1st. Do they recharge the magnets? 2nd. Do they put mag in a wooden box? 3rd. Do they put this box on a wooden shelf.

I called around and most did not recharge the mags. They would state something like, they are ok no need to recharge they work just fine.

I only found one shop who did what I wanted. I did not ask them do you do this and that. I ask them how they did it. Until I found what I was looking for I would just say, thankyou and hang up. I did this because you have no idea how many shops argued the point of recharging magnets.

There is a reason a mag goes into a wooden box then is put on a wooden shelf. The magnets will get weak if you don't, will it still work? Sure. But the magnets will be weak from day one. Keep that in service another 20 years and see what you have. I know everyone replaces mags before 20 years. Right.

You have two mags and from the looks they have metal gears. On something like this I might do as you and replace the bad parts and call it good. I might send the magnets or case out for recharging though.

My 2 cents for what everyone thinks its worth. Lets see, with inflation, I believe I owe you money.

Tony
Click to expand...

My magnetos were made in 1946. They still work fine. Never been "recharged."

That's not to say that some magnetos could use it, but these old Case mags still make a hotter spark than a braand-new Slick.

Points that have been running in oil will be pitted and burnt.

Dan
 
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