20 Most Recent Hitachi NV45AB2 Roofing Coil Nailer Questions & Answers

Your description makes it clear that it needs a head rebuild kit. You can order this from Hitachi, or send it in to local Hitachi center. Good machine, straightforward repair. If you are a little handy, you can do this repair yourself. remember to oil the gun frequently to make your repair last longest. Farmerbear at FixYa

Safety might be bent. You drop it?

I have repair kits and free tech help. airnailerparts.com

Tear the tool down and install #18001 Rebuild kit. Just because the O-rings look good doesn't mean they are not worn. Also make sure you grease the orings with the grease provided in the kit. The entire cylinder has to move up and down in this gun so it is important it is clean & lubricated.

I would suggest going to Hitachipowertools.com and downloading a schematic for this tool and buying a rebuild kit for it. Also check the spring on the advancing pawl to make sure not broken. You would have to thoroughly clean this tool if it is a roofing nailer.Let me know if you need more help.

Needs a trigger kit with the ball

The cylinder is held in place very tightly by o-rings to keep a good air seal between the top and bottom half. Sometimes you have to apply some gentle prying pressure with a screwdriver to loosten it. Be careful as the the cylinder and body are soft metals and can be scratched or bent easily. If prying doesnt' work, turn the gun upside down and hit the egde of the top of the gun, again firmly but not hard enough to deform the head, on your workbench to make the cylinder come out.

If its working ok, dont take it apart, just give it a bath in diesel. Diesel fuel and a small brush will keep it clean and lubed from the outside. Keeping using few drops of oil once or twice a day. If the cylinder is sticking open (air out head when you connect air), remove head and pull out the cylinder and clean /lube with white grease. If the cylinder has fine scratches where orings make contact, sand with very fine sandpaper untill smooth. Make a gizmo that you can turn with drill that will fit into the cylinder and spin the cylinder while you sand. I use a 1.5 inch solid rubber bushing with 1/4 " shaft pushed thru; fits snuggly into cylinder (or just turn by hand). Good luck

Hitachi coil roofing nailer will skip nails if the piston oring is worn, the feed spring is weak or lower bumper is cracked. Easy to check. Remove nails and air supply. With side door open point nose of gun up then down again. If the piston moves up and down in the cylinder, replace the piston oring. If piston does not move and is in the up position, check the feed spring for tension. With air supply removed and door open, slide feeder back and press on feeder from door side to check tension. It should spring back to position against rails.If is feels loose, replace spring and retainer pin if the pin is worn. If piston oring is good, and the feeder has good spring tension, suspect lower bumper and the plastic part below the bumper called the "sheet". Remove head and pull the cylinder to examine lower bumper. Parts are available at www.toolpartsdirect.com. Good luck with your repair

Remove nails and disconnect airline. Open door latch and check for back and forth movement of the feed piston. It should move with little force and should have spring tension when you push on the leading edge of the feeder. If very hard to move then most likely orings are swollen or stuck from lack of lubrication or water entering gun. Remove head being carefull not to tear gasket and check piston/ oring for tight fit( the piston will not come all the way out, just enough to repalce oring). If very tight then all orings should be replaced. If just dry, lube with silicone paste or proper oil. Check that the cylinder retracts into body of gun and rather easily pulls back up. Do not use pliers on the the cylinder; it is spring loaded and shuld move with finger pressure. Parts are available at www.toolpartsdirect.com. Good holidays

SOLVED! I replaced all the o rings put it together and air jus blew out the exhaust port. I made the mistake of pushing Piston plunger cylinder into the gun till it seated. this left a gap between the head and cylinder. I took the gun apart, removed the cylinder, an reinstalled it only far enough to seat past the o ring gasket. I then installed the head and let the head seat the cylinder as I tightened the screws. this worked on two guns with the same problem. Jn 3:17

I have seen roofers that can make the gun sound like machine gun. What they do is fine tune the adjustment on the safety foot up or down and slide the gun against the roofing material while bouncing the gun slightly instead of lifting the gun off the work while pulling the trigger. The safety foot should be pushed against work while sliding the gun from one side to the shingle to the other. The firing takes place when the gun is push down slightly, so that means that the adjustment has to be so the gun does not fire until you press down the final 1/16 to an inch or so. This action wears out the nose however due to rubbing against the shingle. One must balance the faster wear of the nose against greater productivity.

Yes. Roofing nailers all use about the same size and spacing on coil nails. You will find that Harbor Freight is about 1/2 the price of Home Depot or Lowes for those nails.
-Jim

Leaking under trigger could be the ball seal part # 875645 if leak starts as soon as you connect the air hose. If no air leaks when you connect hose but begins to leak when you depress the trigger then replace the oring on the plunger which is part # 874820. If air leaks when you connect the hose and the ball mentioned above is good then most likely is leaking from oring # 876161 installed on cylinder plate (remove head and pull out the plate). Good luck.

Hitachi nailers are built on very close tolerences. Dirt /grit will prevent cylinder from resetting causing air to leak out of top of gun. You can force a reset by striking the gun head first against a rubber mat. Only one or two hits because you could damage the head. If the gun does not reset you will have to take apart and clean out grit and replace orings as needed. Good Luck and post again if you have other questions.