Question about Hitachi NV45AB2 Roofing Coil Nailer

1 Answer

The nailgun only shoots the nail in halfway

Would an air leak cause that? and is it fixable or would i just need to buy a whole new gun?

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  • David Robinson May 11, 2010

    When is the last time you oiled it? What is the pressure your working at?


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  • Hitachi Master
  • 1,378 Answers

The Hitachi nv45 series guns are lifetime guns and parts (parts available at are not too expensive. There should be no air leaks for best results. If air leaks from the trigger area remove the trigger and white plastic plunger. Make sure that the plunger has oring and the ball that the plunger acts against is whole. If air is leaking from the boot around the firing pin then remove the head of the gun and pull off the cylinder ring and check the outer oring. (After you remove the head, the cylinder ring is the part that has two threaded pull points, the outer oring sometimes breaks causing leak) With the head off push the piston all the way down and make sure that the driver extends about 3/16 past barrell. If the end of the driver is wrorn to round shape, you can grind it square if there is enouth length left. If the sheet seal is good the driver will not pull out of the cylinder.(look at parts diag. to find sheet seal, it is below the bumper) If the driver easily pulls out of the cylinder then open the gun from the bottom and examine the bumper and sheet seal and replace as neccessary. If the driver will not pull out of the gun (thats a good thing) then pull up and to side enough to peek/look at the lower bumper to check for cracks or missing pieces. The driver oring should hold the driver in upper position. Check that the top edge of cylinder is smooth and seals against the vinyl part in the head. Use caution not to damage the top edge of cylinder. The oring kit for this gun will cost about $20, however you only have to replace the worn parts for good results. Let me know if your air leak is somewhere other than stated above or other questions. Good Luck

Posted on Jan 23, 2009

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I got air leaking out the barrel where the nail shoots from.

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My Dewalt framing gun blows compressed air thru the nailer nose? Thx Kurt

Rebuild gun with gasket repair kit.
How it works: Compressed air enters through air hose and fills gun cylinder.
When trigger is pulled, air inside cylinder rushes out and pushes firing pin that shoots nail.

Inside the gun there are gaskets that seal the nose, the trigger and the cylinder head.
When any of those three gaskets fail, then air starts leaking.

Putting a few drops of nail gun oil into gun before connecting hose is supposed to protect gaskets.
But everything wears out, and sometimes folks use 3-in-1 oil instead of gun oil.
3-in-1 is detergent type oil and will cause gaskets to fail.

Another thing is guns that are not used frequently and gaskets get dry.
Putting in a few drops of oil and then immediately shooting gun will cause gasket to fail, because gaskets are still dry.
Best to put in plenty of gun oil, and let oil go down into gun for a few hours before connecting hose and shooting. Even so, nail guns are designed to be used every few days with continual oiling.

Add a comment for more free help.
Also take advantage of fixya phone service.
For a price, expert speaks with you over phone while you work on any do-it-yourself project.
Fixya is always less expensive than a service call.

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The cause of this is a misfire or jammed nail that stopped the piston in the wrong location so air will not build in the chamber correctly.

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Check that your air pressure is not set too high. Overdriving nails reduces their effectiveness and can cause tool malfunction.

This problem could also be caused by worn out O-rings or other parts within the tool. If you're not comfortable servicing the tool yourself, take it in for repair/maintenance work.

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