Grinding Noise on CA Mechbox

[Ashton]

'Lo. I recently ordered a used AEG off the classifieds, and I haven't gotten a chance to actually give a few rounds through it until now. Everything was working great at first, though I noticed in semi-automatic it was double feeding a bit. Interested in the rate of fire, I flick it over to automatic and start letting out a few bursts. The first two bursts or so seemed fine, then I got a very, very ugly grinding noise. Panic! I stopped firing and immediately came on here.

Here's the breakdown:

• CA Mechbox, 9.6v 2400 mAh battery, Systema Magnum Long Motor.

• Problem began during automatic firing, after about 30 rounds.

• Grinding noise during either semi-automatic or automatic firing. Grinding noise continues during semi-firing even after the piston should have cycled once. (Approx 1-2 sec. of grinding after trigger release.)

• Using .25 Metal Tech during firing, examined for jamming but there was none.

• Piston currently appears to be fully forward.

• Not firing.

From doing a quick search of the forums it's suggested that this is either a problem with jamming, which I already did a quick search on, or motor height. If this is the case, do I simply adjust that by tightening the flat-head screw on the bottom of my grip?

I'm willing to take the AEG apart and take a gander inside, but I'm not so confident as to not ask for some help first.

Thanks in advance to anyone with advice.

[zone 69]

Sounds like motor height needs to be ajusted. Yes tighten the screw on the bottom of my grip but not to much or it will jam and not move/run. Then put some thread lock on the screw so it wont happen agian.

[Ashton]

Tried going both up and down, but I'm only getting a squealing sound of varying pitch. The only other difference is that the grinding sound is gone and now it simply seems as though the motor is spinning up and not contacting anything, though I might be wrong. I'll continue to try to adjust it, but any tips or advice on how to do this properly beyond guessing would be great, or if this might be another problem. I didn't hear any snapping sounds when this first happened, but I'm obviously concerned that the teeth of a gear may have broken, or is that unlikely?

[Renegade)]

Make sure your grip screws hold the grip plate tight.. I was just working on my buddies gun adjusting the motor because it was overly whiney, and I noticed the front grip screw was loose thus causing the plate to shift.. fixed that, everything tight, no more whine now and the gun shoots crisp again.

[Ashton]

Eugh, I just realized that I haven't even mentioned the fact that it hasn't been firing. It's not just a sound problem. I also took a gander in the feeder and saw a shot on semi-automatic, and the piston only moved very, very slightly. The sound gets very high pitched as I tighten the motor, and more grindy as I loosen it, yet nothing so far seems to "catch" and I certainly don't get the same sound I was getting before. But right now even with the adjustment screw far looser than it began, there's been no indication of improvement.

[The Saint]

Originally Posted by Ashton

Eugh, I just realized that I haven't even mentioned the fact that it hasn't been firing.

I was wondering about that.

Sounds like you stripped something. If you're lucky, it's the piston. Only way to be sure is to open the mechbox.

[rustysniper]

It's broke.....
Sounds like your piston gear is stripped...or has caved in
regardless...sounds like time to crack open the gearbox and have a look...
good luck

[Ashton]

Alrighty. Thanks again. I'll try to get into the thing to take a look. Is this something that would have been caused by prior damage to the mechbox, or am I looking at a self-inflicted problem here? I'm somewhat irked considering this was listed in working condition and I got no more than sixty BBs through it, but at the same time the guy who did the sale seemed very respectable and the custom build was apparently done by wKnight. Don't want to bug the seller if this is entirely my own doing, but I'm not feeling too chipper about not even getting to field the gun before a breakage.

[The Saint]

Very hard to tell. It's possible that the piston was worn down/damaged and already on the verge of failure, or something jammed while you were firing. Insufficient data, cannot compute.

[zone 69]

The first thing I do after buying a used or cheap clone gun is to take it down to have a look for myself if it needs anything done to it. A little bit of proventive maintenance go,s a long way.

[Ashton]

Being a newbie, preventative maintenance for me would usually be not touching the mechbox at all. Regardless, I've followed the MechBox.com guide to opening up a TM M733 up to the part about pushing out the retaining pin for the trigger. The retaining pin on this doesn't want to come out, and I certainly do not want to damage it. I think this might be caused by the paint job on the gun. Any advice on how I can open this further without creating more worries for myself?

[Turnbull]

As a safeguard, when buying a used gun try to get a gun doc to look at it first. I know this isn't very practical, but I sopose it could save you from a situation like this, assuming that the problem was present upon the sale of the gun. This is a lesson I learnt first hand, not trying to preach, I know exactly how you feel right now, and I know that it sucks. The only thing you can do is open her up, take a look inside and call it from there. If I were you I would look into finding a local gun doc, and have him open it. I opened my first gun myself, although I got lucky, I almost lost a few pieces and couldn't place them correctly. If you want to walk the path of doing it yourself, look up your gun on mechbox.com. They have some extremely useful videos on how to take apart and reassemble mechboxes.

Good Luck!!

EDIT: Just saw your last post, disregard the mechbox.com stuff

[Ashton]

Originally Posted by Turnbull

As a safeguard, when buying a used gun try to get a gun doc to look at it first. I know this isn't very practical, but I sopose it could save you from a situation like this, assuming that the problem was present upon the sale of the gun. This is a lesson I learnt first hand, not trying to preach, I know exactly how you feel right now, and I know that it sucks.

It sucks, but I have some degree of faith in the matter. I also got to see a terrible motorcycle accident on the way home from buying my hex bits to open up the grip of the gun, so despite the monetary loss, I'm feeling pretty happy. Could've always been a pedestrian accident, after all! Though, from henceforth, I'll probably avoid purchasing until I'm in Toronto and can actually take a look at most gear before I buy it. And, yes, of course, have a gun doc look at any AEGs/GBBs before money gets put into it.

Edit: Before I run into more woes I'm going to drag this thing up to the South Island Rangers crew, as I'd rather not damage it further in a haphazard attempt to fix it. My primary problem is that the leads on the wire are soldered on to the motor and I have absolutely no equipment to detach or reattach them if I tamper further. I'll probably seek a gun doc in Vancouver if they can't assist me. Thanks all, again.

[zone 69]

Originally Posted by Ashton

Being a newbie, preventative maintenance for me would usually be not touching the mechbox at all. Regardless, I've followed the MechBox.com guide to opening up a TM M733 up to the part about pushing out the retaining pin for the trigger. The retaining pin on this doesn't want to come out, and I certainly do not want to damage it. I think this might be caused by the paint job on the gun. Any advice on how I can open this further without creating more worries for myself?

Frist take out the front and back body Locking Pins and the butt stock off. Then take a small tool and tap the trigger pin out, it should come out the same side as the body locking pins. and if this dose not work try tapping the trigger pin from the other side.