Classic mag leak. Please Help.

[Timber_Ghost]

So I just got a 68 classic in the mail I got through a trade. Excited to use it, I hook up the co2 tank and air pours down the barrel violently. I took it apart and gave it a good oiling and tried again with no luck. If I hold the trigger down the leak stops. I've replace all the orings in the on/off and checked the orings in the power tube, but they look fine. I don't have a parts/ seal kit yet so i'll be ordering one as soon as I get paid next week. Another thing I have noticed is that when I let go of the trigger the bolt comes forward about 1/8".
If I push back on the bolt when it is leaking with my finger, the leak also stops. Ive got a level 7 bolt if that helps. I don't know if maybe I need a stronger bolt spring or what. I've just kind of hit a wall in my trouble shooting. I'm new to classics, so I don't really know what else to look for. I have never encountered a problem like this in my other mags. Thanks in advance for your help.

[dark blade]

sear/bolt/spring combo

it sounds like the bolt spring might have been cut to relieve tension when used with a wave spring on a pumpmag. That very small difference in length can make for a huge problem on a non pumped mag.

Get a longer spring and i bet you will be fine :)

[secretweaponevan]

So I just got a 68 classic in the mail I got through a trade. Excited to use it, I hook up the co2 tank and air pours down the barrel violently. I took it apart and gave it a good oiling and tried again with no luck. If I hold the trigger down the leak stops. I've replace all the orings in the on/off and checked the orings in the power tube, but they look fine. I don't have a parts/ seal kit yet so i'll be ordering one as soon as I get paid next week. Another thing I have noticed is that when I let go of the trigger the bolt comes forward about 1/8".
If I push back on the bolt when it is leaking with my finger, the leak also stops. Ive got a level 7 bolt if that helps. I don't know if maybe I need a stronger bolt spring or what. I've just kind of hit a wall in my trouble shooting. I'm new to classics, so I don't really know what else to look for. I have never encountered a problem like this in my other mags. Thanks in advance for your help.

Easy fix...
...as soon as we figure out the exact cause of the problem.

Since the leak stops when you hold the trigger, your on/off is fine and the leak must therefor be in the powertube.
And since you said that the bolt moves forward a smidge but seals when you push on it, I HIGHLY suspect you are missing your rail bushing at your rear field strip screw. Check for it now please.

You can see this one sticking a bit far out the bottom of the rail behind the sear.
http://www.pentestone.com/paintball/PumpMag/PumpMag%20021.jpg

[Timber_Ghost]

Okay. I'll order some springs and see if that works. On tuna's website There is a spring called the level 10 bolt spring (uncut). Is that that the same as the silver bolt spring. If so im going to order one of those and one of the red bolt springs.

Just for kicks, I pulled the bolt spring out of my RT. (Its the gold one) and tried it in the 68 classic. It made absolutely no difference. Don't know if that info is useful in diagnosing my problem or not.

[Timber_Ghost]

Yeah. I am definately missing that bushing. Do you know the exact name for it or a link to what I need. Since I don't have anything to compare it to, Id like to make sure I order the right part that I need.

Also, does this eliminate the spring from being the culprit? What exactly does the bushing do?

Sorry for all the questions. I just like to get to know my markers because it makes things much easier to fix when you know exactly what mechanisms are failing.

[Beemer]

Yeah. I am definately missing that bushing. Do you know the exact name for it or a link to what I need. Since I don't have anything to compare it to, Id like to make sure I order the right part that I need.

Also, does this eliminate the spring from being the culprit? What exactly does the bushing do?

Sorry for all the questions. I just like to get to know my markers because it makes things much easier to fix when you know exactly what mechanisms are failing.

This is the bushing...........http://store.airgundesignsusa.com/index.cfm?fuseaction=catalog.prodInfo&productID=403&categoryID=92

[secretweaponevan]

Okay. I'll order some springs and see if that works. On tuna's website There is a spring called the level 10 bolt spring (uncut). Is that that the same as the silver bolt spring. If so im going to order one of those and one of the red bolt springs.

Just for kicks, I pulled the bolt spring out of my RT. (Its the gold one) and tried it in the 68 classic. It made absolutely no difference. Don't know if that info is useful in diagnosing my problem or not.

The missing bushing is definitely your problem.

You shouldn't need the springs though it wouldn't hurt to have a fresh bolt spring since you might as well get it shipped with the bushing.

http://www.tunamart.com/index.php?c=39&p=17

Edit: Get the spring and the bushing both from either AGD or Tunaman, don't pay seperate shippings!

[Timber_Ghost]

Cool. Thanks again everybody. I'm gonna order some springs, a spare parts kit and a couple bushings just to have some parts on hand. Ill update the thread to let you know how this all goes.

[211]

The rail bushing makes sure the valve is held in the correct position
if its missing, the valve will set back a fraction of an inch, then even though the bolt is being held by the sear it will wind up sittinmg to far from the face of the valve and it will leak

[Timber_Ghost]

so i installed the rail bushing and ive still got the same barrel leak going on. So now what?

[Spider-TW]

Another thing I have noticed is that when I let go of the trigger the bolt comes forward about 1/8".
What does your sear look like? The catch part should look just like your RT sear. Sometimes people try to "adjust" the catch face of the sear with a file.

The rail bushing is necessary for reliable operation, but it may just have been part of the problem.

*edit*

Also check that the sear pin fits well. I've received a substitute sear pin before that was made from a roller bearing.

[fong0067]

"Leaking down the barrel is always associated with the power tube." Tom Kaye himself said that. If your leak stops when you hold the trigger in your on/off is fine. The culprit I would suspect is a bad power tube oring. Make sure everything inside the power tube is installed right (oring first, then spacer, then the tip that screws in). First make sure everything is installed right in the power tube. If everything is in right replace you power tube oring. If you still have problems you can send it to me if you want (you cover shipping to and from) and I can take a look at it. I am pretty good with fixing these. Let me know how it turns out.


look at this video at about 9:35
http://www.youtube.com/watch?v=VQnGpQYuvlw&feature=related

look at this video from beginning or look around 6:50
http://www.youtube.com/watch?v=huoHWAt_2CI&feature=related

[Timber_Ghost]

well, it looks like my sear may be the culprit. or at least another one. I just went through and replaced all my orings but its still leaky. the front edge looks like it was either filed or broke off. also the sear pin is not the actual pin but is a broken shaft of a screw.... sigh. the more i dig into this thing, the more FUBAR everything looks. I am very much annoyed.

[Timber_Ghost]

so while im waiting for my new sear and pin... could somebody explain to me what is happening that im getting this leak because of my damaged sear. Is the bolt held in place by the front of the sear while the back part of the sear activates the on/off? therefore my bolt is moving forward prematurely because the front edge is not holding it in place when the marker is aired up?

[Spider-TW]

so while im waiting for my new sear and pin... could somebody explain to me what is happening that im getting this leak because of my damaged sear. Is the bolt held in place by the front of the sear while the back part of the sear activates the on/off? therefore my bolt is moving forward prematurely because the front edge is not holding it in place when the marker is aired up?

Sounds right. Consider the differences between the different power tube spacers, about 0.005" iirc. You could try a longer power tube spacer, but 1/8" forward travel sounds like it needs correcting (there is some travel normally because of the angle of the sear and reliable over-travel). 1/16" is 0.0625", so you would have trouble making that up with a spacer. One of the old bronze power tube springs might make it, until it wears out. :)

Make sure your bolt bumper is good as well (blue bumper at least present). If the bumper was missing and you had a sloppy pin, I can see the sear possibly being usable if the rest of it (including the power tube spacer and sear pin) were cleaned up. The trouble is that once a sear starts to wear, they seem to go fast. I've only lost one and it came to me after being filed.

[athomas]

So I just got a 68 classic in the mail I got through a trade. Excited to use it, I hook up the co2 tank and air pours down the barrel violently. I took it apart and gave it a good oiling and tried again with no luck. If I hold the trigger down the leak stops. I've replace all the orings in the on/off and checked the orings in the power tube, but they look fine. I don't have a parts/ seal kit yet so i'll be ordering one as soon as I get paid next week. Another thing I have noticed is that when I let go of the trigger the bolt comes forward about 1/8".
If I push back on the bolt when it is leaking with my finger, the leak also stops. Ive got a level 7 bolt if that helps. I don't know if maybe I need a stronger bolt spring or what. I've just kind of hit a wall in my trouble shooting. I'm new to classics, so I don't really know what else to look for. I have never encountered a problem like this in my other mags. Thanks in advance for your help.If the bolt moves 1/8", when you release the trigger, check that the rail bushing is in place.

Operationally, your mag valve is doing what it is supposed to do. When you hold the trigger, it does not leak. There is no air in the front chamber and the bolt spring holds the bolt in the back position. When you release the trigger, the sear rotates up to hold the bolt and the on-off opens to fill the front chamber with air which pushes the bolt forward against the sear. Generally, the forward movement is much less than 1/8", but if the sear is worn or the bumper is missing, that could account for a longer movement. When the bolt is held in place by the sear, the bolt stem will be resting against the powertube oring effectively sealing the front chamber from leaking air. If the powertube spacer is too long or if the sear is worn, the bolt will sit too far forward to seal properly. Usually there is not enough tolerance to allow 1/8" of movement in the bolt from the rear position to the position where it is being held by the sear. The fact that there is this much movement usually means something is missing or out of tolerance.

Check that your rail bushing is in place
Check the condition of your bumper
Check your sear for wear
Use a shorter powertube oring

[Timber_Ghost]

installed my new sear and pin today. marker is shooting like a champ. Thanks for your help everybody. Its been informative.

[athomas]

Thanks for the update. By posting the fix it helps others that may have the same issues.

Good to hear you you got it working. :)

[Timber_Ghost]

Thats why I did it. Its frustrating when you read a tech thread and have no idea what was actually wrong whith the marker.