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.