# Help with Hitachi NR90AE(S) Strip Nailer



## sjgusmc21 (Dec 16, 2016)

I purchased this nailer are re-manufactured off of Ebay and it worked great until I hit a knot. It started leaking air from the top and the nose, then would only half drive a nail. I proceeded to tear it down, and solved the top air leak and the nose air leak, but it was leaking profusely from the trigger area and would not fire. 

I have replaced every gasket on it, and the three plastic piston parts to the trigger. Tonight, when I tested it, no air leaking until I pulled the trigger and air leaked from the side the trigger housing.

I do not believe I have any bad gaskets, and like i said, I replaced the plastic piston parts of the plunger assembly. It has to be something simple, I just don't know what it is. I do not believe any parts are missing. I have gone over, and over the diagrams and just don't see any parts that I haven't used, missing. 

Any suggestions? I have attached a picture of the diagrams with the parts I have replaced in red. I am trying not to take it to a shop, as I am sure it is probably something I am doing wrong. Any help would be greatly appreciated. 

The url is the diagram to the nailer i have. 

http://www.ereplacementparts.com/hitachi-nr90ae-strip-nailer-parts-c-7927_13310_147615.html


----------



## Nato (Dec 30, 2020)

[


----------



## steves7839 (Aug 18, 2019)

I'm in the process of rebuilding one of this model. The two tiniest o-rings on the trigger valve plunger look rather wimpy and undersized for the grooves they are in. But the trigger valve looks good otherwise. If you replaced these two, it might have been easy to nick the ring or scratch the plunger. I would examine the housing for cracks and scratches on any of the o-ring seating surfaces, then replace the TV assembly in this case.

Going back in time to the initial problem that developed when the nailer hit a knot, did it bend the piston driver?


----------

