Hitachi nail gun,piston/nail push rod wont retract after pushing nail (stays protruding out of gun so the remaining nails stay underneath it

Have you disconnected it from the air source and deep cleaned the nail gun? Sometimes even a tiny bit of dirt can block the rails the rod runs in. Once cleaned add a small amount of oil to the rod runners.

If the nail will not advance, easy test will determine problem. Open door and remove the nails. Lightly tap the nose of the gun against coiled rubber hose or soft wood with door open. If the driver falls to bottom, the piston oring needs to be replaced. The driver should stay at top of cylinder. Next pull back the feeder to rear position and check for tension. The feeder should spring back towards you when you push. Finally, the check paws on the door should return to extended positon when you push on them. Replace springs as needed. Connect air to gun and rapidly bump fire the gun against rubber. The feeder should move back and forward just as quickly as the driver moves. Good luck

it could be you are using the wrong nails, the gun should describe the correct angle and size.

Causes of piston not retracting are as follows. Cracked /worn bumper, if cracked air will leak between piston and bumper. Try test, remove nails and dry fire gun against rubber or soft wood; depress trigger push gun against wood/rubber and hold in this position. Piston should stay down and no air should leak past nose. Worn piston oring, piston should not slide down cylinder under its own weight. Loose or missing check seal, remove cylinder and look for black rubber band around series of holes. Band should be in place and fit snuggly. Good luck

You must have broken tip or out of adjustment. Easy to check. Remove nails, and push safety against scrap air hose or rubber to absorb blow and squeeze trigger. Piston will stay in the down position until your release safety (on some models you will need to pull back on feeder sligtly). While piston is down examine the end of the driver for nice squared off tip protruding about 1/4 inch beyond nose. If no tip or looks broken, replace driver. If tip looks complete, adjust for more depth. Good luck

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,

Cheers

you need a top end rebuild kit

hi visit your supplier and ask for a overhaul kit once fitted your tool will be licke new
best of look ian

The problem that you describe could be caused by three things. First remove the cylinder and look for a black rubber band around the cylinder about med section. There is an indention with holes where it is supposed to be. The band should fit snuggly so that it does not slip off during use. Secondly, check that the piston oring/plastic ring holds the piston in the cylinder without just dropping under its own weight. Third, the upper bumper could have a crack or missing piece. Remove it and check. (vinyl part in headvalve) Parts are available at dewalt repair center or www.toolpartsdirect.com. enjoy