I have an Hitachi nail gun andThe bolts on the nose to the body keep breaking is there a solution to this problem the air pressure is always kept it between 100 psi

could be in need of an internal adjustment to stop the hammer from hitting the end plate ( travelling to far)
talk with a tool repair shop and see if there is something that can be done
contact a a hitachi service agent for advice
go google and type in--- repair manual for Hitachi nail gun-- and see if there is a manual in pdf version that you can download

Easy to check. Remove nails from gun and connect to air supply. Using hard rubber pad or soft wood depress and hold trigger and push nailer safety against pad and hold there. The gun will fire but the driver will stay down until you pull back on the gun and relieve pressure on the safety foot. With driver down examine the tip of the driver. It should look square and should extend about 1/4 inch or more past the nose. If tip is broken replace driver. If lots of air is leaking past the nose during test, also replace the lower bumper. Good luck

Remove all bolts holding the rails to the body of the gun (make note of the position of the parts as you take then off ). Slide out the pusher assmbly. If the spring is good (wound tightly and has the bolt hole), hold the pusher assmbly in hand and attach spring to body of gun leaving bolt loose. Slide the pusher back into the rails and attach rails to body of gun up against the bolt (snug down bolt and check spring action). Re-attach rails to gun. Some after market rails do not have the slot cut into front allowing easy install of spring (cut slot with dremel). Good luck

Sb504000 works just fine with pressure range from 60 to 120 psi depending on material. Any small compressor will work great. Using the gun at max pressure will shorten the life of the gun. Best practice is to set pressure to just under 100psi for most work and increase pressure when nailing hard wood. Using at max pressure will strain the driver and the lower part of gun (screws that hold nose to body). Some hard woods will bend an 18 gauge nail. Good luck with your gun and have fun with your projects.

Over time debris enters the gun and scratches the metal and plastic surfaces where orings seal against. These scratches will allow air to leak past. Remove the head and pull out the head valve. Examine the metal surface with magnify glass where the headvalve oring makes contact. Remove scratches with 400 grit paper. The surface must be smooth and the oring must seal snugly. Apply silicone paste lube on all surfaces and orings (available at Lowes in the plumbing department and swimming pool supply). Also check for scratches around the body of the gun were the cylinder plate is installed around the cylinder. The gun will not work properly will small air leaks. Remove nails and listen for leaks thru the nose of the gun. Repair as needed. Good luck with your gun.

Remove the nails and air supply. With side door open notice position of driver. Driver should be at top position with tip not visible. If driver is down and it moves within cylinder when you tilt nose up then down again, time to replace orings. If driver is down, it should extend past the nose about 1/4 inch (if driver is broken at the tip the end will look rough and nail will not drive in all the way). If driver extends past the nose more than 1/4 inch then lower bumper may be breaking up /cracked. Easy test for proper function. With nails removed and side door open, connect air to gun and dry fire gun against hard rubber or old coiled air-hose (with air connected and trigger depressed, no air should leak from trigger area, if air leaks when trigger is depressed, look for fault at trigger pin). Feeder should move back then forward in quick motion almost matching speed of driver and driver should not creep down between shots. No air should leak from nose of the gun (push nose against hard rubber and depress trigger and hold in this position, driver should stay down with very little or no air leaking out of nose, when you release trigger, driver will return). If air leaks out of nose while holding in this position, replace lower bumper. If a quantity of air leaks from valve in front of trigger, cylinder orings may need replacing or outer part of cylinder has fine scratches (remove scratches with 400 grit paper). Parts are available at www.toolpartsdirect.com. Good lucki

Nail feeder on this gun is both air and spring controlled. Air pressure retracts the feeder and a strong spring pushes the feeder back to front. Remove nails and leave side door open. Dry fire gun very rapidly against thick rubber pad and watch the feeder retract and return. It should move very rapidly all the way back and front again. If it appears to move slower than piston is moving then follow next step. Pull the feeder back manually with tip of screwdriver. It should be very hard to overcome spring. If spring feels strong then suspect feedpiston oring or air supply to feedpiston chamber is restricted with debris from inside of the gun housing or air is leaking where body of gun mates with lower nose. There is a small white oring that seals between body and nose base. Sometimes this oring will be over-compressed thus restricting air flow into feed chamber. Remove two allen screws at front of base to split body from base and reveal this oring. Parts are available at www.toolpartsdirect.com. Good holidays

This is a very popular gun, very light and powerful. Skipping nails is not a common problem. Here are a few things to check that would cause the issue. (First remove air hose and nails.) Worn piston oring (piston will be in the down position). Open side door and check that piston is at top. If oring ok, check feed spring under feeder claw. If spring is in place, push feeder in manually. It should be very difficult to move feeder shaft. If it moves easily then spring inside feeder chamber is broken. If ok, connect air to gun, leaving side door open (nails removed) and bump fire gun against hard rubber (or coiled rubber hose ) very rapidly. While bump firing rapidly, look at feeder moving back and forward. It should be moving very quickly keeping up with speed of driver. If it appears to be moving slowly compared to driver there is an air feed restriction to feeder chamber. Check for debris in small air passage to chamber. Remove two allen screws holding nose of gun to body and examine the small white teflon oring between nose and body(part #149885). Sometimes this oring traps dirt and grime or just simply gets pressed so tightly that center hole is restricted. You must use the correct teflon oring here because the nose and body fit so tightly together that a rubber oring will close air path. Good luck.

Hi,
On that nailer, you have to remove the nail Magazine. And then clear jam thru the sloted open side. And then put the Magazine back on. Usually one big bolt on each side of the nose and 1 or 2 bolts on the rear body.

The roofers that frequent my shop want their nailers to work like machine guns. Here is what I do to make the hitachi 45 nail fast. Remove the cylinder and sand the fine scratches where orings meet cylinder. I use a rubber slug with a small bolt through the center. The rubber slug fits snuggly into the cylinder and the bolt into chuck of drill. Turn the cylinder with the drill while holding fine sandpaper against the scratches untill smooth. remove the nose from body and replace the sheet (part # 877125) and the bumper. If the sheet fits loose on the driver and the bumper has cuts or missing pieces, the driver will not return with full force. also the oring on the piston should not be too tight. Just snug enough to hold the weight of the piston. While nose piece is off check the air passage to feed piston for trash, use a small wire and push through to make sure. Make sure the orings on the feed piston fit snug. Actually push the feed piston by hand in the nose piece to make sure the three orings fit snugly. A loose feed piston will reduce nailing speed. Finally replace the boot on the firing pin. If the boot is blown off its seat with use replace the firing pin. A loose firing pin will waste air and lower pressure reducing nailing speed. Good luck