Question about Hitachi NV45AB2 Roofing Coil Nailer

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Hi, i got a hitachi nv45ab and My nailer leaks air out the back

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Hitachi nv45 series is the most popular line of nailers amoung professional roofers. There are three areas that develop leakes. Leak out head vent indicates cylinder stuck in lower position or headvalve worn. With air connected, gently rap head of gun against rubber mat to move cylinder to position. (Use caution not to damage head). If this action works, gun needs cleaning internally or lack of oil. If air still leaks out vent remove head and examine valve in head and replace as needed. Check that cylinder moves freely up/down (travel aprox 1/4"). If cylinder is hard to move pull cylinder and clean replacing orings as needed. If leaking around trigger, remove rollpin and trigger and check nylon ball for pits and replace as needed. If leaking around base of gun check for loose bolts and/or worn gaskets. Remove nail canaster to check feed piston gasket and screws. Good luck with your repair and post again if you have other question.

Posted on Aug 10, 2010


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My Hitachi NV45AB is leaking air from the trigger air valve. The gun still works if I just keep the trigger depressed and just smack the tip into the shingle.

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.

Apr 19, 2013 | Hitachi NV45AB2 Roofing Coil Nailer

1 Answer

Why does my Hitachi nv45ab gun double fire nails?

This gun should be bump-fired only. Do not place the gun on the work and press trigger. Make sure that the safety spring is in place and has good tension. The spring helps to push the foot off the trigger so that it fires once. You could also adjust the screw that pushes on the firing valve. Turn in or out several turns till head of nail is correct when bump firing then lock the nut. The safety foot fits rather loose on the gun and should still work ok but can get so loose that it falls off the nose. Good luck

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1 Answer

Hitachi NV45AB won't advance nails

This problem could be caused by the head gasket fliped the wrong way not sealing small hole in the body. Also the head valve gasket (small round gasket between headvalve and head) could be place with vent hole mis-aligned. Check these two items and post again.

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1 Answer

I have a nv45ab roofing nailgun & it blows air out of exhaust on top any sug.

Hitachi nailers use an unusual design of actually moving the cylinder to fire instead of moving the headvalve. If the cylinder gets stuck in the open position (down), air will leak out of the head. To reset the cylinder, remove the nails and connect air supply. With air connected, lightly rap the head of the nailer against coiled air hose or soft rubber (too hard of a hit could damage the head). If after a couple of hits air still leaks, remove head and check headvalve for cracks. Replace as needed. If headvalve rubber looks ok, remove cylinder and clean/lube. If cylinder has fine scratches where orings make contact, sand smooth with 400 grit sandpaper. Lube with silicone paste, white grease or nailer oil.

Jul 29, 2011 | Hitachi Tools & Hardware - Others

1 Answer

My hitachi nv45ab double fires

Your nailer has two adjustments that could be the problem. One is just up from the door hinge. You will see a thumb wheel. Turn the wheel till the safety can move all the way up. Next adjust the screw below the trigger plunger by backing off the locknut and turning the 5mm bolt up or down a few turns into a different position. This is the depth adjuster. Most operators bump fire this nailer. Good luck

Oct 21, 2010 | Hitachi NV45AB2 Roofing Coil Nailer

1 Answer

My nailer leaks air out the back my,roofing nailer wont hold any air

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.

Mar 10, 2010 | Hitachi NV45AB2 Roofing Coil Nailer

2 Answers

Hitachi NV45AB coil nail gun is leaking air from top of gun

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

Jan 21, 2010 | Hitachi NV45AB2 Roofing Coil Nailer

1 Answer

I own a hitachi nr90ac3 framing nailer and i

Oil leaking out of the nailer anywhere is just an indication that too much oil is being introduced. A good solution would be to reduce the amount of drops until no more leaks out or use an in line oiler at the gun. An oiler costs under ten dollars and feeds in oil vapor as you use air. Store / hang your nailer with the air inlet down at night to drain out access oil. Do not worry too much about the leaking though, I think that a bit too much oil is better than a lack of oil. Good luck.

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