f4 mag

Mark Poss · Dec 14, 2014

I have had three F4 mags on the same F20. They all start fine, but once I shut it down and go to start it again the impulse does not snap. I can take a rubber hammer and tap the housing and the pawls will free up and works just fine and starts like a champ. All of these mags have been rebuilt by three different companys. Has any one else had any thing like this happen? Thanks, mark.

robgIN · Dec 14, 2014

What are you using to lube the impulse with ? I usually squirt some light oil like a 5w20 that my car and truck use in the hole for the impulse and I rarely have issues with the impulse and I have about a half dozen F4 mag equipped tractors. Now condensers are another story.....seems like a crap shoot whether you are going to get a good one or not any more.

gene bender · Dec 14, 2014

Where have you been getting your conds you are correct lots of bad ones out there for sale.

Mark Poss · Dec 14, 2014

I use 3 in one oil

Tom Fleming · Dec 15, 2014

Mark, I was thinking about this a little more after you called. What type of couple disk do you have? Fiber or steel?

Mark Poss · Dec 15, 2014

The coupler disk is made of fiber

Tom Fleming · Dec 15, 2014

I was reading some of my mag books, and found a reference to where the pawl arms can become magnetized, and consequently won't work consistently or at all.

Since you have used 3 different mags, the only common thing would be the coupler disk, and I have seen those made from steel. If that were to become magnetized, it certainly would be suspect for the symptoms you have.

Ron W · Dec 15, 2014

Yes, It is true that the pawls can become magnetized. I learned this the hard way when on the first F-4 I charged using my newly made magnet charger, I could not figure out what I did wrong as the impusle would not work unless I beat on the mag. An old timer laughed as he told me that I needed to charge the magnet off from the magneto, or I would suffer the issue with the impulse pawl.

I took the magneto off from the tractor, removed the magnet and used a steel bar keeper on it, and then ran the impulse coupler area over a demagnetizer. It has worked fine since.

F-Dean · Dec 15, 2014

If you do not hear the impulse click when you crank your F-20, "Tap" the impulse with the crank.

Oldiron29 · Dec 15, 2014

Mark, After reading all replys, I am woundering if your coupler is binding some? I have had to shim my mag sometimes on the base to get it to align proper. The coupler must be free of pressure from mag to govenor. How do the mags work when you bench test them off the tractor?
Does it only stick when mounted? oldiron29

f4 mag

Mark Poss

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robgIN

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gene bender

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Mark Poss

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Tom Fleming

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Mark Poss

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Tom Fleming

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Ron W

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F-Dean

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Oldiron29

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