Need help on fixing my w4oo gravity spray gun. i have serviced replaced the air valve seat, air valve, o ring and the air valve shaft but cannot stop the air from coming out the air valve shaft behind the trigger they are a basic type setup but this has me stumped. i have also taken to the paint shop and he cannot find the problem and thats his job ???
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Re: iwata w400 air leak behind trigger problem
Have you traced the exact spot of the leak? I will assume you have not. the reason it's important is because if there is a crack in the o-ring seat there is nothing you can do. So trace the leak. Try a small amount of auto air conditioner leak detector or something similar even ink from an ink pen will work. Place it in the air inlet, hook up your air line and trigger your gun for a 10 to 15 seconds. disassemble your trigger and see if you can locate the offending spot. Though this method has worked for me in the past, it's not something I would normally recommend. However the gun you have is to expensive to just write off. The alternative is to contact Iwata and seek help. Good luck.
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Remove the nails and take off the trigger to expose the trigger valve (usually part # tva6). Connect air and spray soapy water on the valve to determine if the air is leaking from the center of the valve or around the outer edge between the body and valve. If leaking from the center, could be defective valve or debris under oring. Pop out the valve and examine internal parts for cut oring or defect. If leaking from between body, you could have cut orings installing the valve. Make sure that there are no rough edges in the body of the gun. Bump fire or single fire happens with the trigger type not the valve. Bump fire trigger is usually black metal and single fire trigger is light color plastic. Good luck
Leak around trigger could be trigger valve internal orings or orings on the outside of the trigger valve making contact against the body of the gun. Spray soapy water to determine where the air is leaking from. If air is leaking around the outside of the valve, most likely the orings were cut upon installation of the valve. If leaking from internal valve, most likely worn or broken oring; easy to fix if you have a source for orings.
To remove the trigger valve for service or inspection (take close-up photo of trigger area for reference ): disconnect airline, remove nails, remove trigger retainer pin, remove trigger, remove roll pin /s holding trigger valve in place (use 3mm punch to remove retainer roll pins which are located in the body of the gun just above the trigger valve). With retainer pin/s removed and with gloved hand (under trigger valve), apply air pressure to gun to blow out the trigger valve (use lower pressure to push out trigger valve because it could come out with force.). With trigger valve in hand notice that there are two slots or groove cut neer top of the valve where the retainer pins rest, you will need to reinstall valve into body with slots aligned to retainer pins. Remove retainer pins holding trigger together to pull out internal valve. Good luck and post again if your have other question about the trigger valve.
This series of nailers are the most difficult to repair. Your nailer has twice as many orings as the norm. Many have said that this nailer is over-engineered. There are three areas that could cause trigger area leak. To make it simple, lets do one area at a time. Use soapy water around the trigger area to find actual leak. If air is leaking from actual trigger valve (ms719-2) and its counterpart, the cartridge (ms719-1) then these two parts need to be removed. Check for scratches in the metal of the valve. If scratched try to remove with fine paper or replace as necessary. Most leaks are due to faulty trigger valve. If air is not leaking from actual trigger valve then remove the dump valve (mn120-5) at the back of the head of gun. There should be two small allen screws then metal lid, then spring and oring. Pull out dump valve and make sure all the orings are in order. This valve should be able to move, not too tight. Use silicone paste lube on all orings (available at Lowes in plumbing department, Danco brand used for faucet orings). Reinstall dump valve and related parts and check for leaks. If air seems to be leaking from bottom of gun neer trigger, most likely problem is cycle valve (mm419-1) and related vinyl seat. These two parts are in the valve housing under the trigger. This valve also moves within its housing and seats on a vinyl oring. This part could be clear vinyl or black rubber. New seats are clear. Inspect these parts for scratches/cuts and lube with silicone paste. Hopefully you would have solved the problem with trigger valve. Good luck with your repair and do not dispare, this is one of the most difficult guns.