I have an rn175 porter cable roof air nailer. I need to know exactly where the check seal goes on the cylinder and which way it goes on, Can you help please

You may disassemble the channel where the nail exits. I have found issues where a burr causes the driver to hang. My issue was on a different type gun.

Could have check valve out of place or broken. Easy to check. Remove head and pull out the cylinder and the round cylinder spacer. Look for black band that should have been covering small holes just below the cylinder spacer. Replace band if broken or if good install the cylinder ring on the cylinder then install the band and finally reinstall the assembly into gun. Look for any broken/cracked parts in the head of the gun. Good luck

Could be the check-band around the cylinder. Easy to check. Remove the head and pull out the cylinder. There should be a rubber band covering a series of pin-holes drilled into the cylinder. Usually the band will fall out of place or break. Use any rubber that will stay in place to cover the holes. Good luck.

Internal damage - most cause by wearing parts
Bring to the repair shop

for technical service (888) 848-5175

866-375-6287 their number

http://www.ereplacementparts.com/porter-cable-rn175-type-roofing-nailer-parts-c-129_1658_1660.html

With most nailers there is a safety device that has to be depressed as you press the gun against the work that is being nailed. This safety device might be damaged or jammed in the firing position allowing the gun to act like an automatic.

put about 6 drops of air tool oil in the fitting and then plug in and shoot some nails to relube the o rings. Let me know if you need more assistance.

Leaking from top is usually caused by the upper bumper (part #886113). This vinyl part will begin to crack/crumble causing improper seal. Order bumper only or overhaul kit #903789 that replaces most parts in gun. Order from www.toolpartsdirect.com. Good luck

I would replace them all. Check the inlet Valve/fitting too.

I too have a Model RN175 Type 1 which will fire one fastener without retruing the driver. This Type 1 does not have the selectable trigger (that allows alternating between single shot and automatic firing). So the previously posted solution (selector mid-way between SS and AS) doesn't apply here. I did a rebuild of the body and replaced the trigger assembly. Still no joy.

I called Porter Cable customers service and technical engineering (888-848-5175 and they suggested check the following items:
1) free movement of the head valve piston and good condition of the spring and o-ring
2) the condition and position of the check seal. This is a rubber sleeve with a lip that must slide up onto the anodized cylinder and COVER THE HOLES. (It has to be installed AFTER the big white plastic cylinder spacer is installed.)
3) the exhaust port to make sure that there was not trash stuck up in there
4) correct air supply pressure
Turned out for me that it was item #2 that was my problem. The rubber sleeve was not stretched up onto the anodized cylinder. This was probably due to initially hitting something hard when nailiing (blew it out of position) then my reassembling it incorrectly.
Hope this helps!
Great nail gun, great company, great customer service!