Question about Hitachi NR90GC2 Cordless Gas Clipped Head Framing Nailer

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Piston not returning.

I have just replaced the cylinder head and gas adaptor on my nailer and now it wont fire properly. It is as if there is not enough power to drive a 90mm nail ans it pushes one out about 10-20mm then wont do the next one and the piston wont return. any ideas?

Posted by Anonymous on


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Posted on Jan 02, 2017

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SOURCE: Can I use paslode roundrive nails in a Hitachi NR90GC Gas Nailer

Yes, BUT the paslode Round drive nails and known to cause driver jamms due to the excessive paper used in the spacing of the nails.

Posted on Oct 31, 2009

  • 382 Answers

SOURCE: Hitachi NR83A2 nailer pushes next nail down

Are you using full round head nails?

The hissing indicates your O-rings are worn out and need to be replaced. This is not covered by warrenty and is common for all nail guns. Lots of kits are available on Ebay or your local Hitachi service center should stock them.

Hope this helps,


Posted on Jan 22, 2010

  • 885 Answers

SOURCE: hitachi nail gun,piston/nail push rod

You have one or more worn o-rings in the head of the gun. They direct the air to the proper parts of the gun to first drive the nail then to return the driver to the top of the gun for the next nail. Depending on the manufacturer and your model number, some companies make kits to replace the o-rings (always replace all of them). For some companies you have to get a breakdown of the gun and order each o-ring seperately.

Posted on Oct 25, 2010

  • 1388 Answers

SOURCE: I have a HItachi NR

Likely that debris is lodged between driver and body of nose or bent driver. Easy fix however.
After many broken drivers, I keep and old driver in my tool box and insert it into the nose of the gun. I have ground the driver slightly thinner to allow for debris or the driver that I am pushing with will also get stuck. A couple of swift raps (use a heavy copper or brass hammer to prevent chips of metal from blasting at you) should push the driver back up into position allowing you to clear debris.
If after a couple of hits and the driver seems stuck solid, suspect broken driver. Remove the head and see if the driver piston looks cocked at angle. If cocked, driver broken. Remove cylinder and remove broken driver. If piston looks square in the cylinder, most likely very stuck driver.
With cylinder removed place body of gun on plywood and hammer on the rod that you are using to push.
After clearing problem and with the gun open, clean all parts with diesel fuel and lube with silicone paste lube (or nail gun lubricant). No need to replace orings if there were no leaks. Look at the lower bumper for cracks and replace as needed. Also make sure that the black band fits snugly around cylinder (black band is one way valve, causes piston to return to top).
Good luck with repair

Posted on Aug 10, 2011

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Now that I have replaced all O-rings and firing valve assembly. Why do the nail heads still hang up with contact on the side of driver rod?

It sounds like your complaint is that the driver isn't returning all the way up and is getting hung up on the next nail?
There is an o-ring on the cylinder near the bottom that covers several small holes around the cylinder (LB1015) - this acts as the check valve and provides the air reserve to push the piston back up - if this o-ring is damaged or missing it will prevent the piston from returning all the way to the top.

26266403-4ukbeyx4iefg4em1tlva0y55-2-0.gif The other thing to check is make sure your driver is not bent or the end chipped / worn.
Best of luck - let me know if this has helped.

Aug 25, 2016 | Senco FP620 Framepro 602 2" - 3 - 1/2"...

1 Answer

My paslode im90i wont reset

Not sure what you mean by reset. If piston driver is not returning this could be caused by a trapped/jammed nail or a damaged O ring quite often the one on the cylinder head. If gun has not been serviced for a while dirt may build up not allowing an adequate seal to be made. In this case clean gun thoroughly with brake cleaner paying attention to area where combustion chamber meets cylinder head also sleeve and piston ensuring the piston rings are not stuck in piston. After cleaning smear a thin coat of oil in the sleeve before putting piston back. DO NOT regularly oil these guns as the gas cell contains a lubricant.

Jan 26, 2014 | Air Tools & Compressors

1 Answer

My bostich1664FN was working fine,then it stopped shooting nails.How can I troubleshoot this problem. Thanks John

Here are some easy tests.
Assuming that the gun is firing normally however no nails are ejected. Remove the head of the gun and check if the piston is not returning to top of cylinder (piston needs to return to top for nail to enter into positon under the driver). Piston not returning to top indicates, bent driver or worn oring on piston. Repair /replace as needed. If driver/oring looks good, pull out the cylinder and look for check band in place around series of holes on lower part of cylinder and bumper should not be cracked. Lube all orings with silicone paste lube. Good luck

Sep 06, 2011 | Stanley Bostitch SB1664FN 16 Gauge...

1 Answer

Model SHBN4. Piston does not withdraw after actuating to allow nail to come into position to be fired.

Piston does not return to top is caused by bent driver, worn lower bumper missing check valve or worn piston oring. Remove the head and pull out the cylinder and driver. Check the driver for bent shaft and that the piston/oring fits snugly into cylinder; make adjustment as needed. The lower bumper should not be cracked or missing pieces. Below the bumper is a seal that should fit snugly around the driver blade. Most all nailers have a check valve around the outer lower part of the cylinder. Could be oring or look like rubber band. This checkvalve will fit snugly over a series of holes cut into cylinder and causes the piston to return to top (not all nailers have this checkvalve). Lube all parts with silicone paste lube or nailer oil. Good luck

Aug 23, 2011 | Itw Devilbiss Tools & Hardware - Others

1 Answer

I hav a coil nailer the problem coming is it fires double nail right after one blank shot , i hav tried everything by replacing its all types of O rings also changed the piston but the problem still...

Remove nails from the canister and test fire the gun very rapidly with side door open against hard rubber (old tire or coiled up rubber hose ) to absorb the energy. Look for driver and feeder to move in time together and driver should return to top each time. If feeder appears to lag behind, check feeder orings and air passage to feeder piston. If driver appears to come out out nose too far or if it does not go back to top every time suspect problem with bumper or cylinder check seal. Look at feed check built into the side door. These must make contact with nails to prevent miss fire. If all appears to look normal, replace the TVA6 valve if the firing pin fits/feels loose in body of the valve. Miss fire occurs when nail checks do not hold nails in place (feed checks on door and feed piston) and or the piston does not go all the way back up so the nail can not feed into place. Less often, miss fire is caused by lower bumper missing pieces /cracking and the crumbeling bumper pieces enter the feed piston chamber preventing the feeder from making full travel forward. One more area to check is the head /headvalve. Remove head and pull out headvalve. Remove fine scratches on surface of head where orings make contact (use 400 grit paper) and lube with silicone paste lube (sold at Lowes in the plumbing department). Finally check the cylinder seal sitting on top of the cylinder. It should fit very snugly against the cylinder and not turn. If it can be turned, replace with new or remove and apply RTV sealant and replace, then wait 24 hours before use. Good luck

Apr 09, 2011 | Stanley Bostitch Coil Framing Nailer

1 Answer

The driver sticks and won't return

Here are a few things to check. It should not be difficult to push driver to top position (should move smoothly up). If difficult to move, remove head and pull out driver to check for obstruction/debris from crumbling bumper or piston oring too tight in cylinder. Repair as needed. If piston moves easily, pull cylinder and replace checkvalve that fits snugly around a series of holes on cylinder (you can also use several orings to fill slot if you don't have new checkvalve band). Replace parts and check for proper function. Piston may not return properly if lower bumper is missing parts/cracked or too worn. Also headvalve parts must be in good order and lubed. Make sure that the upper pumper is not cracked. Good luck

Jan 25, 2011 | Porter Cable Cable Roofing Coil Nailer...

1 Answer

Gun fires, leaves good indentation, no nail. WCE working properly, took head apart to look for jam but nothing in there and am using compatible nails. Also oiled it but no luck. Was working fine doing...

Remove nails and use thin tool to push driver all the way up to top of cylinder. If the gun fires one nail then skips, the driver is not returning to top of cylinder. If no nails fire, then nails are not feeding into proper position. Driver must return to top to allow nails to feed into position. Most common problems are bent driver, worn piston oring and bad batch of nails(head too large). Good luck

Jan 14, 2011 | Campbell Hausfeld 2-in 18 Gauge Brad...

1 Answer

The hammer will not return to neutral after firing. Porter Cable with little use but purchased several years ago.

I removed the head of the nailer and then pulled the hammer out of the cylinder. I removed the o ring and carefully cleaned each part of all particles and blew the cylinder out with an air hose. I placed a couple drops of the proper oil on the slot for the o ring and a couple drops in the cylinder and reinstalled the piston/hammer being sure to match the hammer grooves into the guide/nail slide. I replaced the large o ring in the head mechanism after carefully cleaning and oiling as above. After reassembling, the nailer worked like new.

Aug 04, 2009 | Porter Cable 1" 18 Gauge Brad Nails...

1 Answer

Firing Pin doesn't return

The piston is returned to its firing position by air from the trigger valve after the piston has fired. It relys on the piston sealing against the bumper at the bottom of its stroke, if the bumper was damaged when the driver shattered or it was put in upside down the piston will not return. Also the piston uses air fed into the return chamber from the little holes in the cylinder, if the seal over these holes is damaged the piston may not return. Basically change the bumper and the check seal on the cylinder.

Jul 28, 2009 | Stanley Bostitch Coil Framing Nailer

2 Answers


I had the same issue with an older craftsman 351-18309 brad nailer and crown stapler. When I pulled off the top of the piston, there was a denigrated o-ring. I took an ear bud for my Bluetooth headset, cut it to size and stretched it to prevent it from holding the spring... And I'll be damned it worked! It both tools!!

Dec 06, 2008 | Air Tools & Compressors

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