AEG making loud grinding noise, spring appears to be jammed

Broken34 · September 12th, 2013, 19:26

I ordered an AGM M16A4 last week and it came in the mail today. I literally just came in from firing the gun and I only managed to fire off about 25 rounds before it stopped firing and is just making a loud grinding noise when I pull the trigger. I took the upper receiver off the gun and when I look at where the gearbox is the spring appears to be jammed back and the gun is not cycling. I really hope this is an easy fix, this is really frustrating as I just got the gun today. if anyone knows how to fix this please help! And this is also my first Airsoft purchase so excuse the noobiness.

I really hope a gear hasn't stripped or anything like that

coach · September 12th, 2013, 19:33

Grinding is possibly a motor height issue. The piston locked back means that the gears aren't turning and the anti reverse latch is holding them in place. So the motor turns when you pull the trigger causing the pinion gear to grind on the locked bevel gear.

Let the retailer know. It might be under warranty.

Broken34 · September 12th, 2013, 20:24

Thanks for the reply. I tried adjusting the motor height on the grip and the gun started firing properly for a minute but now it is not firing at all. No noise or anything. Just not firing. I think I will try and return the rifle.

Broken34 · September 12th, 2013, 20:28

Actually, nevermind. I got the gun on blowout clearance from Airsoft GI and there is no warranty or returns. I'm going to have to repair the gun myself..

K3vX · September 12th, 2013, 20:47

You'll have to open the gun to know what's wrong, or have someone open it. If, when you ajusted the motor height, it shot fine for a limited number of cycles, then you are stripping either the bevel (first gear to mate the motor) or the pinion gear (the motor gear).

This could mean that the bevel is shimmed too low, and that you are grinding it slowly until no contact is made. Raising the motor works for a limited amount of time, until you grind the new contact area again.

This could also mean that the gears are binding, which could be caused by a tight shimming of the gears, a spring too strong (for importing) or anything else. This would either cause a jam, the motor would heat and now spin, or if your gears are soft, would eat through it (refer to problem one).

Really, just open it (or have someone else do it if you're not confident) and you'll know the problem, from there, we can figure a solution.

Broken34 · September 12th, 2013, 21:05

I have it opened up and the problem is with the gears. They seem to be ceased up and the grinding sound was just the motor turning without moving the gears at all. I just need to figure out how to open up the gearbox now to fix it. The gears don't appear to be stripped or anything though from I can see through the hole so I think this will be an easy fix (or at least I hope it will be)

coach · September 12th, 2013, 22:22

They are locked up because the sprig is pushing against them but the ARL is holding it in place. Sounds more like the battery isn't giving ton enough juice to cycle so it got to where it is and stopped.

What battery do you have? Charge it up and try again. The batteries and charges that come with most AEG's suck!

Do you have any friends with a reliable battery?

Broken34 · September 15th, 2013, 16:16

Sorry for the late reply. The battery is an 8.4 volt and I do not have access to any other batteries at the moment. I charged the battery for 3 and a half hours before I fired the gun. I tried hooking the battery up to the motor by itself and it seems to be driving the motor pretty hard and I had a good ROF going before the gun ceased up.

Also, I should mention that I stuck a screwdriver inside the gear box and tried turning the gears and they didn't move a bit. I still haven't opened up the whole thing yet though.

coach · September 17th, 2013, 08:22

Look up V2's on mechbox dot com and try to release the ARL. The gears will never turn with the piston locked back and the ARL engaged.

Get a new battery and charger if they are the stock ones that came in the box. Especially if the charger is a wall wart dumb charger!

ThunderCactus · September 17th, 2013, 14:59

If you adjust the motor up too high that will also cause the gun to jam
Adjust it up until you feel it press against the gear, then back it off half a turn.

Stealth · September 17th, 2013, 15:04

I think we've all concluded that you have to open it up.

Picking and prodding at it from the outside typically fixes nothing.

Ultimately you'll want to shim the pinion/bevel interface properly, then the spur and sector gears last. Don't forget to apply a touch of blue loctite to the motor height adjustment screw in your pistol grip so it doesn't loosen over time.

lurkingknight · September 17th, 2013, 15:06

^ I'm with this guy/s

or a bearing let go.

Broken34 · September 17th, 2013, 18:31

So I took the gearbox apart and I think the problem is that the gear wasn't catching on to the piston to pull it back. (don't know the names of the gears yet sorry) I reassembled the gear box for a second and put the motor in and quickly dry fired a few shots and it was working properly, but I had to open it back up because I didn't put the wires back in the right. Now I'm having problems with putting the anti reverse latch back in, it keeps popping out unless I hold it down and it is a huge pain in the ass. But anyways when I opened up the gun I turned the gears manually with everything assembled and it didn't always catch on to the piston and when it didn't it made the same type of clicking noise it did when I was firing the gun and it wasn't working. So I think the problem is that the gear that moves the piston is failing to catch on to the teeth on the piston.

K3vX · September 17th, 2013, 18:45

Pictures?

ThunderCactus · September 17th, 2013, 19:55

Not really physically possible....
If it failed to catch the piston teeth even once, it would strip that piston.

By the sounds of it, what I'm pretty sure happened is you stopped firing the gun with the piston almost all the way back, and your setup just doesn't have enough torque to move the piston with that much spring pressure on it. Coupled with the fact your motor height likely wasn't adjusted from factory (it happens), there's your problems lol
Once you get your motor height correct, if it locks up again, just put a larger 9.6v battery on it and see if that frees it up.

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September 12th, 2013, 19:26	#1
Broken34 Trader rating Join Date: Sep 2013	AEG making loud grinding noise, spring appears to be jammed I ordered an AGM M16A4 last week and it came in the mail today. I literally just came in from firing the gun and I only managed to fire off about 25 rounds before it stopped firing and is just making a loud grinding noise when I pull the trigger. I took the upper receiver off the gun and when I look at where the gearbox is the spring appears to be jammed back and the gun is not cycling. I really hope this is an easy fix, this is really frustrating as I just got the gun today. if anyone knows how to fix this please help! And this is also my first Airsoft purchase so excuse the noobiness. I really hope a gear hasn't stripped or anything like that Last edited by Broken34; September 12th, 2013 at 19:28..

September 12th, 2013, 19:33	#2
coach aka coachster Trader rating Join Date: Mar 2008 Location: T dot	AEG making loud grinding noise, spring appears to be jammed Grinding is possibly a motor height issue. The piston locked back means that the gears aren't turning and the anti reverse latch is holding them in place. So the motor turns when you pull the trigger causing the pinion gear to grind on the locked bevel gear. Let the retailer know. It might be under warranty.

September 12th, 2013, 21:05	#6
Broken34 Trader rating Join Date: Sep 2013	I have it opened up and the problem is with the gears. They seem to be ceased up and the grinding sound was just the motor turning without moving the gears at all. I just need to figure out how to open up the gearbox now to fix it. The gears don't appear to be stripped or anything though from I can see through the hole so I think this will be an easy fix (or at least I hope it will be) Last edited by Broken34; September 12th, 2013 at 21:09..

September 12th, 2013, 20:24	#3
Broken34 Trader rating Join Date: Sep 2013	Thanks for the reply. I tried adjusting the motor height on the grip and the gun started firing properly for a minute but now it is not firing at all. No noise or anything. Just not firing. I think I will try and return the rifle.

September 12th, 2013, 20:28	#4
Broken34 Trader rating Join Date: Sep 2013	Actually, nevermind. I got the gun on blowout clearance from Airsoft GI and there is no warranty or returns. I'm going to have to repair the gun myself..

September 12th, 2013, 20:47	#5
K3vX Trader rating Join Date: May 2012 Location: Quebec City	You'll have to open the gun to know what's wrong, or have someone open it. If, when you ajusted the motor height, it shot fine for a limited number of cycles, then you are stripping either the bevel (first gear to mate the motor) or the pinion gear (the motor gear). This could mean that the bevel is shimmed too low, and that you are grinding it slowly until no contact is made. Raising the motor works for a limited amount of time, until you grind the new contact area again. This could also mean that the gears are binding, which could be caused by a tight shimming of the gears, a spring too strong (for importing) or anything else. This would either cause a jam, the motor would heat and now spin, or if your gears are soft, would eat through it (refer to problem one). Really, just open it (or have someone else do it if you're not confident) and you'll know the problem, from there, we can figure a solution.

September 12th, 2013, 22:22	#7
coach aka coachster Trader rating Join Date: Mar 2008 Location: T dot	They are locked up because the sprig is pushing against them but the ARL is holding it in place. Sounds more like the battery isn't giving ton enough juice to cycle so it got to where it is and stopped. What battery do you have? Charge it up and try again. The batteries and charges that come with most AEG's suck! Do you have any friends with a reliable battery?

September 15th, 2013, 16:16	#8
Broken34 Trader rating Join Date: Sep 2013	Sorry for the late reply. The battery is an 8.4 volt and I do not have access to any other batteries at the moment. I charged the battery for 3 and a half hours before I fired the gun. I tried hooking the battery up to the motor by itself and it seems to be driving the motor pretty hard and I had a good ROF going before the gun ceased up. Also, I should mention that I stuck a screwdriver inside the gear box and tried turning the gears and they didn't move a bit. I still haven't opened up the whole thing yet though. Last edited by Broken34; September 16th, 2013 at 19:59..

September 17th, 2013, 08:22	#9
coach aka coachster Trader rating Join Date: Mar 2008 Location: T dot	Look up V2's on mechbox dot com and try to release the ARL. The gears will never turn with the piston locked back and the ARL engaged. Get a new battery and charger if they are the stock ones that came in the box. Especially if the charger is a wall wart dumb charger!

September 17th, 2013, 14:59	#10
ThunderCactus Not Eye Safe, Pretty Boy Maximus on the field take his picture! Trader rating Join Date: Feb 2007	If you adjust the motor up too high that will also cause the gun to jam Adjust it up until you feel it press against the gear, then back it off half a turn.

September 17th, 2013, 15:04	#11
Stealth Mr. Silencer Trader rating Join Date: Dec 2001 Location: Toronto	I think we've all concluded that you have to open it up. Picking and prodding at it from the outside typically fixes nothing. Ultimately you'll want to shim the pinion/bevel interface properly, then the spur and sector gears last. Don't forget to apply a touch of blue loctite to the motor height adjustment screw in your pistol grip so it doesn't loosen over time. Last edited by Stealth; September 17th, 2013 at 15:07..

September 17th, 2013, 15:06	#12
lurkingknight "bb bukakke" KING! Trader rating Join Date: Jul 2011 Location: Ottawa	^ I'm with this guy/s or a bearing let go. __________________ I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know.

September 17th, 2013, 18:31	#13
Broken34 Trader rating Join Date: Sep 2013	So I took the gearbox apart and I think the problem is that the gear wasn't catching on to the piston to pull it back. (don't know the names of the gears yet sorry) I reassembled the gear box for a second and put the motor in and quickly dry fired a few shots and it was working properly, but I had to open it back up because I didn't put the wires back in the right. Now I'm having problems with putting the anti reverse latch back in, it keeps popping out unless I hold it down and it is a huge pain in the ass. But anyways when I opened up the gun I turned the gears manually with everything assembled and it didn't always catch on to the piston and when it didn't it made the same type of clicking noise it did when I was firing the gun and it wasn't working. So I think the problem is that the gear that moves the piston is failing to catch on to the teeth on the piston.

September 17th, 2013, 18:45	#14
K3vX Trader rating Join Date: May 2012 Location: Quebec City	Pictures?

September 17th, 2013, 19:55	#15
ThunderCactus Not Eye Safe, Pretty Boy Maximus on the field take his picture! Trader rating Join Date: Feb 2007	Not really physically possible.... If it failed to catch the piston teeth even once, it would strip that piston. By the sounds of it, what I'm pretty sure happened is you stopped firing the gun with the piston almost all the way back, and your setup just doesn't have enough torque to move the piston with that much spring pressure on it. Coupled with the fact your motor height likely wasn't adjusted from factory (it happens), there's your problems lol Once you get your motor height correct, if it locks up again, just put a larger 9.6v battery on it and see if that frees it up.

AEG making loud grinding noise, spring appears to be jammed

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