How to shrink a oring - Air Tools & Compressors

Air leaking from nose of gun indicates air getting past bulkhead orings. Bulkhead is white plastic frame inside of gun. Replace gold colored vinyl orings with like size buna orings. Remove cylinder from bulkhead to find two bad orings. Also replace trigger valve or vinyl orings within valve including the two orings on the firing pin. Good luck.

you have to replace the orings.. those tubes pull out.you will have to split the carbs.. be careful of the little spring on the throttle link popping out when removing, and remember to setup the choke link again afterwards. Not a big job. While ur in there, make sure the gas hasnt left a brown residue inside arb, GENTLY scrape it out it its solid - without scoring the aluminum.. so the oring will seal well. Do not use any rtv/silicon, this is a low pressure system and good viton orings will last years -

Unless you have a crack in which case sand around the area to create a key, get some 2 part epoxy and let it cure overnight. Also go all the way round, that will keep the epoxy from chipping/peeling off, although this is a low stress part - better to be sure .. pulling carbs isnt always fun.

Also - when removing carbs, try avoid leaving boots off for too long, they will slowly shrink and it will be a nightmare to get them on - esp an inline 4.. You can always soak them in hot water of use a hairdryer to soften them up..

Dewalt nailers have some vinyl orings that fail. Usually found within the trigger valve, headvalve, and between the cylinder and cylinder spacer (white plastic piece). A dewalt nailer with failing orings may not leak air however. The vinyl orings tend to start to crumble and the tacky-crumbling pieces tend to create a seal. Easy way to check condition of the vinyl seals in a Dewalt is to remove the trigger valve and look at the orings on the firing pin/stem (2mmx1.5mm orings). If these two orings are soft and sticky, then orings inside of gun most likely the same. Check band on the outside of the cylinder (part # 390159-00) is what causes piston to return to top. But also check to too tight or too loose piston oring, bent shaft of driver and worn/ broken lower bumper. If all is well with internal parts and piston does not return to top, too much air is leaking past nose of gun. Oring kit sold by dewalt will contain most of the orings needed. The kit may not have orings for the trigger. You will at need two orings (2mm x 1.5mm) for the trigger valve stem or just replace the valve. Use white grease or silicone paste lube on all the orings. Good luck.

May need cylinder seal # bc0438. When this seal fits loose or is cracked, air will leak past and push piston down to bottom of the cylinder. If the seal fits snuggly and looks in good order, suspect headvalve orings and cylinder spacer orings leaking. Order oring kit and seal. Use silicone paste lube on all the orings. Look carefully at the surfaces where orings make contact and remove scratches with 300 grit sandpaper(fine scratches will allow air to leak past new orings). To make the gun work with poor fitting orings. Clean inside of gun with diesel and apply plenty of silicone paste to orings (using same orings if not cut or broken). If gun works as normal, the silicone paste is temporarly sealing the orings. It may continue to work for a while untill you get new parts. Good luck with repair.

This means both banks have a lean condition. Most likely if you have a 4.0 SOHC motor your upper intake is sucking in air at the orings at the bottom of the intake. These are really bad about when they are cold in the morning the shrink and let air get by and after the engine warms up the orings soften and seal off.

This sounds like a problem within the trigger assembly itself. If you did not repalce the trigger, you may need to do so. There are internal rubber orings that may be deteriorated enough to fail when cold. They may be shrinking enough to allow air passage. I have had the triggers fail on me over the years. I consider this normal wear and tear.

Dan

There are two types of regulators used. One has a rubber diaphram sealed at perimeter with body and a piston type. Most likely you have the piston type. Remove body containing piston/ spring mech. Examine piston lip seal. Lip will face toward body of reg. and must fit snugly into cylinder. Make sure cylinder is smooth and is well lubed.
If seal/piston fits loose remove seal and wrap some teflon tape in groove and re-install lip seal /test for snug fit. Notice small metal actuator extending from center of reg. , if it is circular (about 1/8 dia) then there should be an oring of the same size mated/fit into the piston. If this oring is missing it will leak as you describe. Lastly, there should be a gasket or oring sealing outer shell to body. If you have diaphragm type look for holes, tear or shrink too small. Parts are at www.toolpartsdirect.com or Lowes in the plumbing department good place for orings and silicone lube. Good luck

There are two types of regulators used. One has a rubber diaphram sealed at perimeter with body and a piston type. Most likely you have the piston type. Remove body containing piston/ spring mech. Examine piston lip seal. Lip will face toward body of reg. and must fit snugly into cylinder. Make sure cylinder is smooth and is well lubed.
If seal/piston fits loose remove seal and wrap some teflon tape in groove and re-install lip seal /test for snug fit. Notice small metal actuator extending from center of reg. , if it is circular (about 1/8 dia) then there should be an oring of the same size mated/fit into the piston. If this oring is missing it will leak as you describe. Lastly, there should be a gasket or oring sealing outer shell to body. If you have diaphragm type look for holes, tear or shrink too small. Parts are at www.toolpartsdirect.com or Lowes in the plumbing department good place for orings and silicone lube. Good luck

The oring on the headvalve/piston should be replaced. You can use any oring that fits snugly on the groove. Factory oring is vinyl but use black rubber oring, works just fine. Most likely place to find orings is Lowes in the plumbing department. Select oring smaller than groove so that it will fit snug and should be about 1/8 in thickness. There is a smaller oring behind piston, just make sure it not cracked and check for upper seal in head to be in place. Finally check that surface there oring seals on head is not scratched. Remove fine scratches with #400 grit paper.

Your float needles and or seats are probably the cause. Of course check the fuel line itself first, if it is ok, remove the carbs then turn upside down and remove the bowl. (do one carb at a time to keep parts in order) the float will be made of plastic (sometimes brass) and as the fuel level rises in the carb it "floats" up causing the needle to seat and stop fuel flow. Check for dirt and debris on the needles. If none found, then remove the needle seat (a brass plug that the needle goes into) it should have an oring that goes between the seat and carb body. This oring will shrink over time and if it does not seal tightly it will allow fuel to leak. You can get the o rings at a auto parts store if you take an old one for sizing it will be cheap (less than 5 bucks)