98C rear bolt o-ring cutting?
Printed From: Tippmann Paintball
Category: Paintball Equipment
Forum Name: Gun Maintenace and Repair
Forum Description: Important info for keeping your marker in top shape
URL: http://www.tippmannsports.com/forum/wwf77a/forum_posts.asp?TID=145926
Printed Date: 25 May 2026 at 3:38am
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Topic: 98C rear bolt o-ring cutting?
Posted By: Guppzor
Subject: 98C rear bolt o-ring cutting?
Date Posted: 03 December 2005 at 2:34am
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First post, so lets see how I go. If I get any terms/names mixed up or wrong, please let me know. First a bit of a background to the problem: I have/had a problem with my new 98 Custom. The first time I took it out for a shot, the problem was that the marker would fire fine for a while, and then all of a sudden would start cycling more than once per trigger pull. After a bit of head scratching I decided to pull the marker apart and see if there was any crud in the internals (such as styrofoam from the box etc). Everything was clean and oiled. I did notice what looked like casting 'dags' around the rear bolt's o-ring. I tidied it up a little bit, oiled it, and re-assembled the marker. It shot fine for a little while, and then started stuttering (cycling more than once) again. I ran a little more oil through the ASA, and it seemed to fix it. Then today whilst playing, it started back up again. I took it to the tech at the field and he had a bit of a look at it, cleaned the old oil off and re-oiled it, changed the rear bolt o-ring, and it went OK for a short time befor doing one of the following: 1. Start cycling more than once per trigger pull and recock 2. Barely push the paintball out of the end of the barrel and recock (just) 3. Fire fine, or fire as per either of the above two and *not* recock 4. Not firing at all (i.e. no gas being released, rear bolt not hitting the valve stem hard enough) After a bit more head scratching, we stripped it apart again, and the new o-ring was starting to look a bit like the original one (i.e. looked like it had casting 'dags') and had a bit of a closer look at the rear bolt, and where it slides into the rear of the valve. It *seemed* that the rear part of the valve was a bit... square (i.e. a hard edge) which was catching the o-ring slightly as it was travelling forwards, slowing the rear bolt down enough to cause the above problems. The tech (who has never seen that problem before) chamfered off the hard edge, oiled it all up, re-assembled it, and now it seems to be going much better (it certainly sounds more... consistant I guess). Velocity jumped from ~285fps when it fired correctly, to over 350fps, so obviously there is much less resistance as the rear bolt passes into the back of the valve housing. I have not checked the rear bolt o-ring yet, but I will be having a look at its condition tonight when I strip it for some cleaning. My question(s): 1. Does this sound like the solution to the problem? 2. Has anyone else had a similar problem? 3. Is there anything else that it may be, and chamfering the edge off is just "masking" the real problem? Thanks in advance. |
Replies:
Posted By: ShortyBP
Date Posted: 03 December 2005 at 9:15am
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Hmmmm... that's a new one for me. But I can picture it.
I think so long as that "snag" has been eliminated, all should be fine now. With all of the symptoms you had, one leading cause would have been a worn or bad rear-bolt O-ring. If you are able to cycle now without damaging that rear bolt o-ring... the problem *should* be solved as far as I can see. Over the years I have not had this problem with any of my Tippmanns, nor do I know of anyone personally who has. BUT... all it takes is one simple flaw in the manufacturing process for something like this to slip by QC. While your descriptions were very detailed and specific... I'm still having a hard time picturing exactly where the snag was. My immediate thought without you saying anything would have been a rough edge on the receiver half somewhere that slipped past during the casting process... but your rough edge was on the actual valve body? Either way... I would see if the latest "fix" does the trick. I think it will. If it doesn't, please bring it to our attention and hopefully some of us can help you out... and upon that failing, would suggest that arrangements be made to send the gun back to Tippmann for free servicing. Hopefully it won't come to that, as a 'done-at-home' remedy would be much simpler and less time consuming. Welcome to the forum! Sorry that you had to come under such circumstances. |
Posted By: Guppzor
Date Posted: 03 December 2005 at 8:03pm
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The snag seemed to be where the rear bolt enters the back of the power tube, and on the actual power tube itself, rather than on either of the reciever halves. I took it apart last night to clean up some paint that worked its way in, and the o-ring definately looks much better. Hopefully the problem has been fixed. Edit: Just a side question, I noticed that the sear spring is different to the diagram in the manual. The one in my marker is a straight spring, not the ones with loops as shown on in the manual. The position of the sprint on the sear is also different. Why the different spring type? |
Posted By: ShortyBP
Date Posted: 05 December 2005 at 8:50am
| Hmmm... that I don't know. All of my 98s have the sear springs with loops. Haven't seen one with a setup different from that. |
Posted By: Snake6
Date Posted: 05 December 2005 at 8:55am
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Maybe he has CP internals? idk ------------- 
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Posted By: Guppzor
Date Posted: 08 December 2005 at 5:27pm
| Just having a look on Tippmann's online product manuals, and I noticed that one of the PDFs was titled "98 Custom with New A-5 Sear Schematic". This is the correct diagram for my 98 Custom. |
Posted By: Corteo
Date Posted: 22 May 2006 at 8:44am
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I know this post is old, but my new Tippmann C98 is experiencing the exact performance problems in Guppzor's post. When I try to re-insert the rear bolt into the valve, it is an extremely tight fit (even when the o-ring is oiled). Thus, I am sure that the problem afflicting my gun is the same as Gupp's. Would anyone recommend on how to "file" the inside of the valve in order to allow more space for the rear bolt to travel forward. I have never done this before, and thus fear damaging it, please be as detailed as possible. Thank you. ------------- 
-Joe |
Posted By: Bruce A. Frank
Date Posted: 22 May 2006 at 11:25am
It is not the valve, it was the rear edge of the power tube (the plastic tube inside which the valve fits). Getting rid of a sharp rear edge to allow smooth entry of the "O" ring is not a precision operation. There is just a need for a small chamfer...and the part is plastic. It could be done with careful scraping of the inside edge with a pocket knife.
Corteo, you don't have to apologize for actually doing a search that turned up information that you needed. This isn't a "bump" of an old topic, it is the correct use of the forum resource with a request for clarification. Way to do it! -------------  
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Corteo wrote:
Posted By: Corteo
Date Posted: 22 May 2006 at 7:15pm
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Thanks for the response, Bruce. However, I did what you said and a new problem has presented itself. Once the trigger is pulled, the gun does not stop cycling until the CO2 is depleted or I physically stop the rear bolt from moving (whichever comes first). I am currently trying to solve the problem. -------------
-Joe |
Posted By: Bruce A. Frank
Date Posted: 23 May 2006 at 2:53am
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Cycling like that is an indication of low pressure, as when the CO2 tank is nearly empty. There is not enough pressure to blow the bolt (hammer) back far enough for the sear to engage. If the sear and its actuation spring are in good condition and the notch in the rear bolt where the sear engages is sharp (not rounded over), low CO2 is the likely culprit...and it is normal. If you have a regulator installed it is possible to set the pressure too low which will also cause the full auto cycling, otherwise it is usually just low CO2. -------------
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Posted By: tigman250
Date Posted: 23 May 2006 at 10:18pm
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in the first post he described high then low velocities wich is a sign of loose or missing valve bolts. this would also cause eratic wear of the rear bolt o-ring if the valve is floating arround. may want to check yours too? ------------- http://img76.imageshack.us/my.php?image=stickemup6of.jpg"> 
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Posted By: Corteo
Date Posted: 24 May 2006 at 7:58am
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I went to a Pro Shop yesterday and had the owner look at my gun. Apparently, large amounts of liquid CO2 is entering my gun causing my O-rings to freeze and cause friction (so much CO2 in fact, that the level of condensation made me look like I was firing an old musket, due to the high level of "white smoke" escaping from every orifice). He then slapped on an HPA tank, the gun then began to fire flawlessly. The gun did not stutter at all. Seeking a cheaper solution to my problem, I purchased an expansion chamber. However, the stuttering and inconsistent velocities are still occurring, causing my gun to fire, on some occasions, five balls with one trigger pull (leading to much ball breakage in my 12" barrel). Tigman250, can you please elaborate on the missing valve bolts. If this solution does not work, I will be forced to switch to HPA (which I'm willing to pay for if it will indeed, fix my problem). Thanks again to all users who posted. -------------
-Joe |
Posted By: Bruce A. Frank
Date Posted: 24 May 2006 at 12:42pm
These guys that hold the power valve in place. Parts # 8 in the schematic.
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Posted By: Bruce A. Frank
Date Posted: 24 May 2006 at 1:02pm
The dealer is trying to sell you an HPA tank. Though not a bad idea, there is a reason that liquid CO2 is entering the marker in such significant amounts. There is nothing wrong here, it is just something along the lines of a very full freshly filled tank, a marker held with the muzzle pointed down so that liquid CO2 is what is actually exiting the bottle (rather than the gas), or a firing rate that is so high that the CO2 in the tank foams up pushing liquid into the system. Certainly HPA would will eliminate all the problems associated with CO2, just be aware that the dealer is misleading you a bit. The problem of liquid CO2 entering the marker system has solutions, but even those solutions can be overwhelmed when the marker is manipulated to cause the liquid CO2 to flow out of the tank. I can take a 98C with expansion chamber and a Palmer Stabilizer installed and make it blow CO2 snow out of the muzzle (and all other openings in the marker body). Fixes include that expansion chamber, but additionally you need an anti-siphon tube in the tank for best performance. The tube reduces the likelihood of liquid going into the expansion chamber or the Palmer. Though some liquid can still make the trip, those devises can usually handle it. Another method is the remote. The long tube from the tank on your back to the ASA on the marker allows for any liquid to turn to vapor before reaching the marker. Again, all these "solutions" are un-necessary when you switch to HPA. -------------
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Posted By: Corteo
Date Posted: 24 May 2006 at 4:54pm
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The Pro Shop owner made it evident that he wanted to make a sale, but the reason I brought it up was because the marker fired without complications when the HPA tank was affixed to it. Regarding the valve bolts, I don't think that's the problem since both are firmly screwed in and the threads are coated with loctite. -------------
-Joe |