Air leaking through nose constantly. I believe that I have ordered all the proper o rings to repair the problem, but I need to know how to remove the cylinder.

If you are going to repair (or try to repair) it yourself, start disassembling it to find that "O-ring". When you find it and confirm that it's exact place where it leaks, just search for the proper size rubber ring. They are available in all sizes (yes, your miles may vary, and it may take a few days for delivery if you order online). However usually you can find separate elements on your own.

Good luck,

Mike
Cisco Compatible Headset Adapters for 7940 7960 etc

recheck the "O" rings for one rolled over or nicked when assembling
put a small screw driver blade under the "o" rings and travel around the piston several times to allow the ring to settle in properly

Jerry,
I sent you a request because I don't know if iam getting all of the question and bugging me. But Nose 's I know. I just don't know what you have? did the oring squish out or something or is it just leaking air from the nose? so if you just want to replace it you will have to remove the bolts that hold the nose on should be hex most are I work at thomasindustrialsupplyinc.com so most of the things like bostitch have mm hex bolts although some have torx. But take off the guards and you should expose all the bolts. if its a bigger gun ( stick or coil) you'll have to remove the magazine. but no big deal. just keep all the parts segregated and don't lose anything will come off pretty smooth. the bolts will require a bit of effort depending on again the size of gun. I have found like the bigger ones take the 6mm hex while the finish take the 3mm hex and while the little ones are less tight sometimes strip the head. but the bigger guns may require a torch to the side to warm up and deactivate the threadlocker they put on the bolts. And depending on how the Nose is attached some have an oring that just sits in a groove while others have a ring that sits snuggly around it. If its one that sits in groove, add some light lease to it and that will be enough to hold it in place when you are assembling it .
If air is leaking its not the nose oring because the air shouldn't get that far down until its fired. so it could be other orings like around the spacer ring or the driver/ piston oring.
keep us posted

Shooting continusously caused by worn orings in the trigger valve and in the gun.Dewalt framing nailers use some vinyl orings (gold or clear in color) that fail too soon in both the trigger and the cylinder spacer (white plastic). Air out the nose of gun indicates air is leaking past the cylinder spacer seals (If piston is pushed down with air leak then headvalve seal is leaking (remove nails for this test)). If piston is not pushed down with leak, remove head and pull out the cylinder with cylinder spacer (white plastic). Place the cylinder on workbench with bottom up. Push down on locking ring and remove retainer to release all the other parts. Take picture or take note of parts together and as you pull them off to aid in re-assembly. You will need to replace the two orings between the white cylinder spacer and the cylinder. Order oring kit from dewalt or just purchase one ( # 141 universal oring ) and one metric oring 74.4mm x 3.1mm from hydraulic parts store. If the piston was pushed down with air leak, replace headvalve orings in the head. The trigger valve also has vinyl orings on the trigger pin. You could try replacing the orings but hard to find . Pin uses 2mm x 1.5mm. The orings on the inner valve should fit snuggly on the outer contact surface. If the valve just falls out the the body, the orings are too loose or the body is worn. I would just replace the trigger valve to be safe, however repaired works ok if you can find the orings. Trigger orings do not come in the kit. I would also remove the nails after each use and only reinstall them after air is connected and gun seems to work as it should. The Good luck with your repair.

Dewalt framing nailers use some vinyl orings (gold or clear in color) that fail too soon in both the trigger and the cylinder spacer. Air out the nose of gun indicates air is leaking past the cylinder spacer seals (If piston is pushed down with air leak then headvalve seal is leaking (remove nails for this test)). If piston is not pushed down with leak, remove head and pull out the cylinder with cylinder spacer (white plastic). Place the cylinder on workbench with bottom up. Push down on locking ring and remove retainer to release all the other parts. Take picture or take note of parts together and as you pull them off to aid in re-assembly. You will need to replace the two orings between the white cylinder spacer and the cylinder. Order oring kit from dewalt or just purchase one ( # 141 universal oring ) and one metric oring 74.4mm x 3.1mm from hydraulic parts store. If the piston was pushed down with air leak, replace headvalve orings in the head. Good luck with your repair

Make sure no nails in gun. With air connected listen for leaking thru nose of the gun also. If leaking thru nose slightly, air is getting past the cylinder seal oring and/or top of cyl is not seating against headvalve. Repair leak to nose of gun before trying to fix head leak. With no air leaking thru nose of gun, add plenty of white grease to orings in the head (one oring at a time) to see if leak is less and/or grease will streak behind the leaking oring. Then repair as needed. May need slightly thicker oring or sand surface where oring makes contact to remove scratches that are allowing air to pass. Also air can enter the head thru the small port in the gasket leading to the head (make sure that the gasket is sealing).

Trigger leak is easy to repair. Your nailer uses a valve # tva6 and is sold on ebay or many other web locations for about $20(generic valve works good also). To remove the valve, remove the trigger by removing the pin (3mm). Now remove the pin/s holding the trigger valve. With gloved hand apply air to gun and catch the valve as it pops out. Use caution because the valve could come out with force. If you would like to try to repair the valve, remove two pins holding the valve together. The center spool has three orings. The middle oring is usually the problem. It is a bull nose vinyl ring that splits. You could try replacing the oring with a normal oring, however it must fit very tight to work properly (no need to replace any of the other orings in the valve). I have successfully used regular oring instead of bull nose(purchased from Lowes plumbing department). Good luck

sounds like the packing is shot. you need to oil it 2 times a day if its a constant use tool, drain your compressor everyday if its below temps do it twice a day. before removing the packing try putting lots of oil 10 drops into the nailer it might just be **** caught in it but **** can ruin the packing.

The most troublesome part within the cnp65y is #knp-me-110-3p1, cylinder ring assembly. If this part is bad, air will leak out the nose. This white plastic ring seals the cylinder to body and is visible when head is removed. Pull cylinder and remove the ring. Examine for cracks or anything unusual and replace as needed. Available at www.toolpartsdirect.com. Good luck with your repair.

Lets assume you have oiled the gun. Before you run out and buy an o-ring kit for this, take the gun apart and look for anything that may be jammed inside the gun. This could be dirt, grit or an unfired nail. The gun is very simple inside so don't be afraid to do this yourself. Undo the 4 hex screws holding on the cap at the back of the gun. Put the nose of the gun in a vise or get a friend to hold the gun for you. Grab hold of the cylinder inside the gun and pull it out. Wiggle it around and pull at the same time, it will be tight but it will come out. Totally disassemble the cylinder. If the seals look good take a very close look at the "Bulkhead". It is made of plastic and is prone to get very small hairline cracks in it and this will leak air. Look inside the cylinder and make sure the walls are smooth and not scored. This is all very easy to do. Don't just buy an o-ring kit assuming it will fix the problem. Look for the simple stuff first, it may save you some time and money. AGAIN IF THE O-RINGS LOOK GOOD TAKE A VERY CLOSE LOOK AT THE BULKHEAD AND LOOK FOR CRACKS, IF AIR IS LEAKING FROM THE NOSE THIS SHOULD BE THE FIRST PLACE TO LOOK AND COSTS ABOUT $7.00 TO REPLACE..........