PC finish nailer does not retract al lthe way,

[Bill Dufour]

I have used Porter Cable finish nailer I bought used.. It is made in Taiwan so a bit older. Plastic cylinder si I do not know if it is oil free or not. The piston failed to retract the last 1/8 of an inch. This means the nail heads can not advance into the line of fire. I took the cylinderhead off and cleaned the cylinder, piston and hammer rod. This helped for 4 shots but now it is not quite retracting all the way again.
Thers is something wrong with the retracting valve action. I pull the trigger and shoot a nail nail. That works fine but then there is a slow hiss for about one second instead of a instant double fire hiss to retract the piston.
Is the valve in the cylinder the retraction valve? Should I take it out and clean it? I do not really understand the valveing for a nail gun.
Bill D

[Michael Pyron]

the most straightforward solution is to replace the driver (available as a kit with an O-ring)...what is really at fault is the O-ring...you didn't by any chance at some point use 5 in 1 oil did you? I tried that once in a bad pinch and while it worked for a bit in the end it just gummed up and caused the symptoms you describe...it had degraded the O-ring to the point it required replacement. in my case it was a Porter Cable brad nailer, which requires lubrication (cough...of the correct variety, something similar to sewing machine oil)...if your gun is an oil-less variety then it is still most likely the O-ring, but may also be the cylinder it sits in...if it was the O-ring in the trigger area then most likely it would always be hissing and the gun wouldn't even fire...

[Bill Dufour]

The piston does not have an o ring. Just a split ring which looks good.

[Bruce Wrenn]

The piston does not have an o ring. Just a split ring which looks good.

Look under the split ring and see if it uses an "O" ring to expand the split ring.. My Sencos use such a set up.

[Roy Petersen]

I had a Bostich coil nailer doing that, and after dissembling it, realized the diaphragm that pulses air to the return was deformed and pretty much flattened. Once that was replaced it was back to working fine. Without knowing your model, I found this diagram.
https://www.ereplacementparts.com/po...1717_7635.html

The parts on the far left appear similar to what was in mine. That small protrusion on that top cap is where the return burst of air that powers the "after stroke" air is directed. Check your head assembly for dirt, corrosion or deformation/broken bits.

[Tom M King]

Never been in one of those guns. Is the split ring white?

[Bill Dufour]

The split ring is black. I understand it is plastic, looks like graphite.
I will take the stuff under the cap off and see if it is gummed up. The cylinder was a bit gummy so that sounds like a good idea now that I know that is where the return air is valved from. Thanks
Bill D

[Tom M King]

I was really curious what the split ring was for. I don't recall seeing one in my old Senco guns. A firing seal did split, and that was replaced. I had to heat it with a heat gun to get it on. At first it, looked like it had to have that split to get it on, and off, but that was incorrect. The problem was the split. I looked at the diagram posted earlier, but am not sure if that is the correct model or not.

[Bill Dufour]

There is a small setscrew in the head that I managed to strip the allen head out. I think it needs to be removed to pull the head valve which is leaking. I found a used gun that works for $40 so rather then a build kit for around $30 I will get another gun.
There are many on ebay used that do not retract.
Bill D.

[Tom M King]

I'll remember not to buy one of those. Some of the Senco guns I'm still using were bought new 45 years ago. At the same time that I bought those new ones, I also bought a couple of used ones. I don't know how old the used ones were then, but I'm still using them. A few drivers (the plunger that drives the nail/staple) have worn out, and been replaced, but the only seal I've replaced has been the firing seal in the SN4, that I was talking about earlier.

[Jim Dwight]

I have a PC and a couple Bostitch nailers but will just buy another Harbor Freight if they ever give me trouble. They are so inexpensive you can normally buy one for what the rebuild kit would cost. They also work fine. I have a framing nailer, 15 gauge, and a framing nailer that might actually be worth fixing, the cost $60-100. But my Bostitch 16, and 24 gauge and a 18 gauge I think my soon to be ex-wife took that is PC will just get replaced if they act up.

[Mike Barton]

I have a PC finish nailer also and last Saturday as I was finishing up some shelves...same thing, misfired and wouldn't retract all the way. I disassembled, checked everything over, and was scratching my head when my wife remarked how quiet the air compressor had been all afternoon... ooops.... it was down to 55 pounds psi, turned it back on and everything worked fine...duuuuh... check your air supply !!!!!!

Mike B

[Bill Dufour]

Got the used one in the mail today. it was not feeding right until I realized the nails that came with it were 18 gauge not 16. Now it feeds fine and piston retracts all the way. It also has a constant hiss from the cylinder head so I may return it since I think the seals are on their way out.
Bill D.

[Rich Engelhardt]

When it comes to PC nail guns, you have to check out which model it is before you plunk your money down.

Some can be rebuilt, some can't - even some of the same model numbers stopped being rebuildable! You have to check the revision number of the model (A,B,or C).