Question: Gravermax G8 - no throttle control, just blows air

Bob A

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Jan 25, 2014
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167
Hi - Relatively new Gmax8. Suddenly just blows air with no power (can increase speed, but no power to handpiece). Right now have it hooked up without Airtact, so I know the connections are right.

  • Checked all internal hoses; no leaks apparent.
  • No throttle control at all.
  • Motor assembly spins fine and responds to dial.
  • No air leakage when off.
  • Only air leakage under power is "puffing" at the two way switching valve.
  • Will not 'hold' pressure on front indicator.

Now, the Airtact internal filter blew out for unknown reasons. This is the first time I've used it since that debacle, so I'm guessing that's a contribution.

Any ideas?

Thanks, Bob
 

Bob A

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Jan 25, 2014
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167
Thanks, Carlos. Already did, have done what they initially suggested, looking for some ideas before they open again tomorrow. I'm sure I'm not the first one to have this problem.4
 

fegarex

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Bob,
If you haven't tried it yet I would "back flush" the regulator. Take the hose from the compressor and connect to the outlet of the regulator. Leave the inlet open to blow out any contaminates. The "inlet" of the regulator is the hose coming from the back of the machine.
 

Bob A

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Jan 25, 2014
Messages
167
Thanks for the suggestion, Fegarex! I did exactly that, but regretfully no change.

Additional notes:
1. It seems to be running very loudly. Initially I thought it was just because I had the housing open. However, when I gently lift the spinning thing on top of the motor assembly as it turns, the growling noise almost ceases. Bearing?
2. When I power on and off, I get a good "popping" sound of the valve opening and closing.
3. The handpiece vibrates a little, but all vibration stops when I put a finger on it. No power at all.

4. This seems like a clue - it doesn't sounds as if the foot piece is leaking *any* air at all (never thought I'd miss that!).

I am stumped... Any further thoughts?

Thanks, Bob
 
Last edited:

fegarex

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Messages
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Location
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Bob,
Perhaps the solenoid is dirty. That is the "pop" you hear. The noise is normal but it might be plugged. You can try to bypass it first. It is located right inside of the box. If you have a chunk of air hose, run it from the filter outlet to the regulator input.
 

fegarex

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Bob,
A dumb question but did you mess with the handpieces? The spring should be closest to the front of the handpiece. It's a common issue to get them reversed. Check those before doing the solenoid.
 

Bob A

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Fegarex, with me at the controls nothing is a foolish question! Negative on hand piece foolery, to be sure checked by using an older one. Rehosed as you suggested, pop is a bit less loud, no other change. I think I'm beat, I've moved so much that some of the connectors are no longer crisp. I really thank you for the help, looks like I'll be boxing it up. At this point I think I have to figure whatever toasted the filter in the air tact may have done a job on the graver max...... Again, thank you so much!!
 

fegarex

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Bob,
If it is possible, call when you are by the machine and perhaps we can track down things.
Rex
 

DakotaDocMartin

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Grand Forks, ND
I don't know if it would cause all of those symptoms but... have you checked the adjustment on that barrel under the foot control. I had that loosen up and got out of adjustment and it pretty much acted like you are saying. Just a thought. I think there is a thread here about that.
 

Marrinan

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I had the same trouble with my daughter's G8 and it turned out to be the selector knob. When set on right outlet setting it was a little out of line and stayed in neutral. just found the sweet spots and put new marks. to switch too.
 

Bob A

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Jan 25, 2014
Messages
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I had the same trouble with my daughter's G8 and it turned out to be the selector knob. When set on right outlet setting it was a little out of line and stayed in neutral. just found the sweet spots and put new marks. to switch too.

Hi - Good thought. Could be a contributor, though I did try the adjustment you suggested to no result. I'm beginning to think it may be a couple of things; we'll see what the GRS wizards say!
 

Bob A

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Joined
Jan 25, 2014
Messages
167
I don't know if it would cause all of those symptoms but... have you checked the adjustment on that barrel under the foot control. I had that loosen up and got out of adjustment and it pretty much acted like you are saying. Just a thought. I think there is a thread here about that.

Hi, Doc - Thanks for the suggestion. I checked the foot control, and all appears to be exactly as it was (no moved index marks, etc.). I think I'll have to see what the GRS wizards say.... Thanks - Bob
 

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