Rebuild a Framing Nailer

Rebuild procedure

1 of 3

Photo 1: Work from the top down

Remove the four hex screws and then the cap. Then remove the entire cylinder and driver assembly.

2 of 3

Photo 2: Walk the ring off and on

Pry up the old O-ring. Then slide the round portion of the screwdriver under it. Circle the screwdriver around the O-ring to “walk” it off. Reverse the procedure to install the new, freshly greased ring.

3 of 3

Photo 3: Swap out the trigger valve

Locate the roll-pin driver tool and tap it out with a small hammer. Then pull out the valve and install the freshly greased replacement.

Nothing beats a top-quality nailer for cutting hours out of a framing project. But all that heavy-duty nailing depends on a handful of rubber O-rings. When they fail, your project grinds to a halt. You don’t have to wait a week for the shop to rebuild it. You can do the entire job yourself in about two hours and save money in the process. I’ll show you how to rebuild a Bostitch framing nailer with a master O-ring kit and a trigger valve assembly. If you have a different brand, don’t worry. The rebuild is similar for others.

Framing nailers usually fail in one of these ways: deteriorated O-rings that cause air leaks, a trigger valve that won’t fire, or a leaking cylinder seal or a worn driver bumper, which prevents the gun from making a complete stroke. A complete rebuild fixes all those problems. Buy the rebuild kit at a local service center or online. It’ll come with all the O-rings and seals. If you’ve put a lot of nails through your gun, buy new bumpers and a trigger valve at the same time. Then download the gun schematic from the manufacturer (bostitch.com, senco.com or, for Duo-Fast and Paslode brands, itwserviceparts.com).

Start the disassembly at the cylinder cap (Photo 1). Lay out the pieces on a spotlessly clean workbench in the order you removed them. Then remove the old O-rings using a blunt, straightblade screwdriver (Photo 2). Apply O-ring grease (usually included in the new kit) to the new rings, then replace the rings one at a time, matching each one to its replacement. Install the new bumpers, piston seals and piston stops and reinstall the cap. Then replace the trigger valve (Photo 3).

Prolong the life of your air nailer by using only nail gun oil.