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Another pmag question

danny

danny

Well Known Member
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My motor was acting funny when throttled back in the pattern. No popping or weird drama, just an uneven idle. It's never done this before. I ended removing the mag and discovered a very small but perceptible amt of play in the shaft. Book says as much as .030" (?) is ok. Danny says no. Asking the brain trust what your thoughts are.
Thanks
danny
 
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Very common problem with pmags. the play messes with the internal sensor gap and you have issues. Needs to be sent in for repair. Be sure your sitting when looking at the new repair rates. have no idea what amount of slop in the bearing is allowed, but if it has already translated to poor performance then the spec doesn't matter.

Are you sure ignition is the source of the rough idle?
 
danny said:
My motor was acting funny when throttled back in the pattern. No popping or weird drama, just an uneven idle. It's never done this before. I ended removing the mag and discovered a very small but perceptible amt of play in the shaft. Book says as much as .030" (?) is ok. Danny says no. Asking the brain trust what your thoughts are.
Thanks
danny
Click to expand...
When I called E-Mag, they said any discernible play was unacceptable and needed to be sent in for a rebuild. My P-Mag has been at the Hartzel rebuild shop since May 7th for rebuild.

Edit: 250 hours on my P-mag 😰
 
mfleming said:
When I called E-Mag, they said any discernible play was unacceptable and needed to be sent in for a rebuild. My P-Mag has been at the Hartzel rebuild shop since May 7th for rebuild.

Edit: 250 hours on my P-mag 😰
Click to expand...
The .030" is from the troubleshooting guide. 105 hours. We're you quoted a $$ amount? Really poor timing here. The airport is going to close for a couple of months starting in July so I was hoping for a bit of flying before that. Did you have any symptoms or were you just doing your annual? Pmag went from hero to zero overnight.
Thanks
danny
 
lr172 said:
Very common problem with pmags. the play messes with the internal sensor gap and you have issues. Needs to be sent in for repair. Be sure your sitting when looking at the new repair rates. have no idea what amount of slop in the bearing is allowed, but if it has already translated to poor performance then the spec doesn't matter.

Are you sure ignition is the source of the rough idle?
Click to expand...
99.9% sure. The T/S guide says .030" is max. I don't like any amount. It was uneven and almost died on the ground without giving it a little stick. Checked plugs maybe 7 hours ago. My motor doesn't run rich. Filter is good. All the other stuff is good. I have an engine monitor and will download later. Mag is an obvious potential issue. Hopefully the only one. And, yes, will be sitting maybe with an adult beverage to cushion the blow.
danny
 
Can’t find any quantitative reference to the end play other than “excessive play” in the current 114 manual or troubleshooting sections
 
Mikeyb said:
Can’t find any quantitative reference to the end play other than “excessive play” in the current 114 manual or troubleshooting sections
Click to expand...
Me neither but the factory told me any play you can feel when aggressively wiggling the shaft indicates the need for overhaul.
 
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