20 Most Recent Dewalt D51321 3/4" 1 3/4" Heavy Duty Coil Roofing Nailer, 70 120 Psi Questions & Answers

Try Home Depot or Lowes

I dont know this particular piece of equipment but it sounds like a broken return spring

Most nailers have a two position setting on the trigger to allow for single fire or bump fire. If set on bump fire, the gun will work better when you bump fire the gun instead of placing the gun on the work then depress trigger. Bump fire works best when safety spring has good tension. Easy test. Make sure that the safety spring is in place (with air hose removed, contact foot should spring back quickly when pushed against work). With air connected, hold trigger and quickly bounce the gun against the work. If the gun does not fire when you bump, the trigger is most likely set to single fire. With trigger set to single fire, you must place the gun against the work, then depress trigger. If the gun shoots two nails while set to single fire, most likely worn trigger or worn out trigger valve. These parts are not expensive and are easy to replace. Good luck

I have noticed that Dewalt uses some vinyl orings in the trigger and the interior of the nailer that fail with time no mater if the gun is used or not. Vinyl orings will soften over time and will need to be replaced. I use buna or viton orings available from many suppliers including (oringsandmore.com). You will need to carefully measure for correct size. I use 2mmx 1.5mm orings on the trigger stem. Good luck

Several things to check. Below the bumper is a small plate that should fit snugly around the driver and keeps air from leaking past the driver. The bumper should not be cracked or missing pieces, replace as needed. On the outside of the cylinder below the cylinder seal, there is a row of holes that should have a snug fitting oring, this is the check seal that causes the driver to return (some nailers have a rubber band covering holes). Finally, the driver oring should allow the driver to move easily down cylinder but not allow the driver to fall under its own weight. Good luck

When the driver or headvalve is stuck in place and the gun is fired, there will be a pop sound or the sound of air being released within the gun and at the trigger. Remove the nails and air supply insert metal rod into nose of gun forcing the driver against headvalve (a couple of firm taps will do). Retest gun. If no joy, remove the head being carefull with head gasket. The driver should be at the top positon (if driver drops to bottom of cylinder replace oring). Pull the driver and lube the piston oring seal. Headvalve should move in with thumb pressure, if stuck, remove and clean / lube orings. Replace parts as needed if scratched, cracked or generally worn. Use plenty of silicone paste lube on orings ( sold at Lowes in the plumbing department and swimming pool supply stores). Good luck

what I would recommend is removing the belt and running just the motor. I think that the bearings on the armature are seizing up and creating the noise. The fan bearing is hard to remove. Let me know if this is the case and I will give you directions on how to do it.

On the side of the nose there is a paw that's driven by a piston to feed the next nail into place. Check that the paw isn't damaged and moves freely. The piston has several o-rings that do wear out or break over time. If they are damaged you will need a rebuild kit for the gun if Dewalt still makes one for this gun. Go to http://servicenet.dewalt.com and look up your gun. There are two types for this model number so I don't know what parts to recommend. If a kit isn't available for the feed piston you should be able to order the o-rings seperately.

Try cleaning and oiling the slide,and make sure there is no debris on the slide when oiling,use wd 40 and then wipe it clean,then just use the air gun oil on the slide.

This is more likely to be a problem with lubrication than anything else. Check to be sure that the main housing is well lubricated. You should be adding pneumatic oil to the gun periodically with the air. It is possible that the o-rings have a leak as well. Remove the top cover and check for lubrication and the condition of the o-ring seals. Replacement o-ring kits are available for around $40.

Dan

First does it retract after unplugging the air and if so I would look at the trigger valve assembly for a sticking plunger. If not then I would look at the firing valve in the cap. Let me know if I can help further.

I have heard complaints that this saw does not do well on angled cuts because of its low power. Try running a shorter and/or thicker extension cord and checking your input voltage. That's about all I can think of, hope it helps.

before tearing apart spray gun plunger and shaft with carb cleaner than spray with a spray lube like wd40 sometimes the plunger gets debris on it if still misfiring call dewalts 800 number they can advise of local repair shop and also advise if problem can be fixed by u

You need to check the piston oring for damage. If the driver slides through the cylinder without much resistance this is part of the problem, if not all of the problem. Check the cylinder for scarring on the inside where the driver travels. If you see long scratches the cylinder needs to be honed out or replaced plus the driver oring replaced. You also need to check the two o-rings at the bottom section of the cylinder. These will be in grooves on the cylinder which will have holes behind one of them. If these are weak they will not be sealing off the air well enough to return the driver. Air goes through these holes on the down stroke then it seals so the pressure built up in the lower chamber will force the driver back up. To replace the driver o-ring and the 2 lower cylinder orings would be about $5. You may want to try this before getting the o-ring kit. An o-ring kit is $42. If you cannot locate the problem individually you may want to replace all the o-rings in the kit. This should solve your problem as long as there is no scarring in the cylinder. Any questions please post back