How to Repair a Bostitch Framing Nailer

Air tools make light work of tasks that used to take years to learn. A framing nailer can cut the work of roughing in frames, from a single room or small garden shed, to a whole house in half. Bostitch nail guns, made and sold by hardware giant Stanley, ease the task for amateur and professional carpenters alike. The most common problems with most nailers, Bostitch included, is air leaks caused by degraded O rings, and trigger valve seals.


Materials Required

  • Allen wrench
  • ring kit
  • Ball peen hammer
  • Tool oil
  • Metal punch
  • Trigger valve assembly

Replacing O Rings

  • Remove the four mounting screws holding the vent cap on the back of your framing nailer, just above the handle. Use an Allen key to remove the screws, turning them counterclockwise. Lift the cover from the rear of the nailer.
  • Pull the plunger cylinder from the gun. This appears as a solid white plastic disk, just inside the back of the nail gun. Use a small flat screwdriver if you need to lever it up then grab the rear of it, pulling firmly to remove the plunger from the chamber.
  • Inspect the O rings for deterioration. If any of the O rings show signs of wear, replace all. O rings are the round, black gaskets fitted around the plunger cylinder. Depending on the model of your nailer, there will be one or two at the rear of the cylinder and one or two at the front. The kit also comes with a flat rubber washer that fits to the front of the cylinder. Replace the washer as well.
  • Use a cotton swab to apply a small amount of Bostitch air tool oil to each O ring and the rubber washer and install them on the cylinder in the same location as the originals. Placement may vary from model to model. Consult the maintenance manual for more specifics.
  • Reinsert the plunger into the rear of the tool and reinstall the vent cover, threading the four mounting screws back into the body of the nailer. Tighten them with the Allen key.

See Bostitch Framing Nailer Reviews below

Replacing the Trigger Valve

To get your nailer back in the game, you’ll need to replace the trigger valve assembly. You can take your gun to a service center and pay roughly $75-100 to have it done, or you can buy the kit for around $27 and change it out yourself. The repair is easy to do; the only tools you need are a hammer and a pair of pliers, and you’ll be up and nailing again in about 15 minutes.

The kit contains everything you need to change out the valve—the valve itself, a little roll pin to knock out the retaining pins in the gun, and a small tube of grease to lubricate the assembly when you install it. The kit was the TVA11, in my case; this same kit works for several Bostitch models. If you have a Senco, Dewalt, or other brand, many will have a similar fix; type your gun’s model number and ‘trigger valve repair kit’ into a search engine to get the right kit, or check the manufacturer’s website.

To begin, make sure your nailer is disconnected from the air hose. If you don’t, you’ll also need a change of underwear shortly after you begin the disassembly process. Lay the framing nailer down on a large rag or an old towel, to help corral the pieces as they tumble out. Hold the little roll pin from the kit on the end of the retaining pin for the trigger and gently tap it with your hammer until it pops out. The trigger will drop free; set it aside with the retaining pin.

Next you’ll pop out the retaining pin for the valve the same way. My gun has one pin, some models have two, and you may have to peel back the black rubber cover slightly to access the pin(s). Set the pin aside so it doesn’t get lost.

Once the valve pin is out, there are two ways to remove the trigger valve assembly—manual or turbo. Usually, if you grab the valve’s plunger with a pair of pliers, you can slide it right out. If it doesn’t (because perhaps you’ve been a bit lax with the daily lubrication), or you just want to add a dash of excitement, grab a rag and wrap it well around the area the valve will be exiting, and connect a lightly charged air hose to the gun’s coupling for a second or so—the valve will make a speedy exit from its little hidey hole. You’re halfway done!

Take a good look inside the cylinder the valve came out of, and make sure there are no little pieces of debris left behind. (If you used the jet propulsion method, there shouldn’t be much of anything left in there!) Pop the cap off the new valve body (roughly the top third), and lubricate all the o-rings on the assembly with a light coat of the provided grease. Snap the top back on, find the grooved side of the valve, and make sure when you insert the valve the groove will line up with the retaining pin when you re-insert it.

Push the valve GENTLY into the bore, being sure to keep it square to the valve body so as not to tear the O-rings. When it’s all the way in, start the retaining pin back into its hole, again making sure the groove in the valve body lines up with it, and tap it gently back into place using the roll pin.

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