Hitachi NV45AB2 Roofing Coil Nailer - Answered Questions & Fixed issues

Safety might be bent. You drop it?

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 have repair kits and free tech help. airnailerparts.com

Needs a trigger kit with the ball

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.

Remove the 3mm roll pin holding the trigger in place and set aside the trigger plunger (white plastic plunger should have an oring on groove). Remove the fitting that holds the trigger plunger and replace vinyl ball #875645 or check for debris under ball. Good luck with your repair.

Replace the trigger

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.

If air is leaking from the trigger, check vinyl ball and oring on the white plastic firing pin. If air seems to leak from the plunger just in front of the trigger (with air connected and nails removed move plunger with finger and listen for change in sound), remove the head and pull out the cylinder. The outer oring to the plate around the cylinder is bad, however, clean the cylinder and lube with white grease. Good luck

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

The feeder pin used by hitachi has a shoulder on one side and a rubber washer /retainer on the other. There is only one groove and the retainer fills the groove and if the correct pin and spring, no extra room to fit an exstra retainer unless the shoulder is worn so bad that the pin is falling thru the plunger. I have seen a lot of creative ways that owners use to hold the pin in place due to lost rubber retainer or lost pin. I also see many guns that have installed a retainer pin from porter cable which has two grooves (one on each side of the pin and no shoulder ). Porter cable pin works fine and fits perfect. Good luck

Remove the head and check that the cylinder moves down and then up again. If the cylinder is stuck stuck down, remove outer ring and pull out the cylinder. Check for grit and or scratches where the orings make contact. If scratched, remove with fine sandpaper, lube and reinstall. Check that the cylinder is in the upper position before you install the head. If the cylinder moves down then up again, check headvalve seal (rubber seal in the head) for cracks or the rubber has become loose and spins. If loose reseal with RTV. If cracked, replace with generic or factory part. Good luck

Cylinder guide fits very snuggly into cylinder and generally does not need to be removed unless visually broken. If you have a leak and suspect the orings under the guide, re-post a question. If however you want to pull anyway, I use one arm of a large two arm puller. Remove the outer ring, pull out the cylinder, then gently tap the under side of the guide with the lip of the single arm. Move the arm from one side to the other and it will come right out. Second method is to remove lower half of the gun and push out with rod or hardwood dowel. I have remove many by tapping up with lip of puller and have not damaged any. This part is quite strong, however have not ever needed to replace the orings under this part. Good luck

The nail guide is held on by a pin with a rubber cap on top of it. If you remove the cap the pin will slide out and the guide will come off. You can go to www.ereplacementparts.com and do a search on your model number to see a good breakdown of your gun and the parts we're talking about.

Air leaking around the trigger area could be caused by vinyl ball / gasket under trigger valve bushing or orings within the gun. Easy test, remove nails and connect air (assuming that air is now leaking around the trigger area). Depressing the trigger stops the leak, replace vinyl ball. Depressing trigger does not stop leak, move plunger b (plunger B, small shaft under bubber bushing next to the trigger valve) with your finger in then out to determine if air leak changes tone. If air leak changes sound or tone, then air is leaking past orings of the cylinder guide and/or cylinder plate and/ or the cylinder itself is scratched by debris where the orings make contact. Pull out the cylinder and examine the contact areas. If scratched, use 300 grit paper to smooth, if smooth, however, suspect the orings of cylinder guide (or cylinder guide is cracked). The cylinder guide is difficult to remove and install without causing damage to guide or cutting new orings when installing. Do not remove the guide unless all the other options have been checked. One last bit if information, I have noticed that some guns will leak air if the orings on the feeder piston do not fit snuggly. Make sure that leaking sound is not coming from feeder area (remove the basket and feeder/feeder pin/spring and pull out the feed piston, making sure that the largest oring is making good contact within the cylinder). Good luck with repair.

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

the top!! o-ring inside of thr top plate is bad you need to remove the plate /dissasemble and replace the o-ring

Two areas to check when air leaks from around the trigger. Rubber ball under trigger pin will cause air to leak, however when good side of the ball falls on the seat, air will not leak for a while. If air is leaking from plunger pin (just in fromt of the trigger pin), remove the head and pull out the cylinder plate to reveal broken oring (oring part # 876161). Good luck with your repair project.

Oil it. "O" rings or seals might be dry. May need replacing.

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.