Dripping HVLP gun

Troubleshooting a dripping spray gun. March 29, 2000

I think I may have purchased a "lemon" spray gun.

I bought an Accuspray Model 19 HVLP gun and had problems right off the bat, getting the gun to spray an even pattern and to stop leaking. Because it was new, I took it back for a replacement. The second gun worked great for about an hour and now drips after each spray and release. Is this typical of this gun? Anyone out there have similar problems?

Forum Responses
What are you spraying with the gun? I know it is poor manners to answer a question with a question, but all spray guns can drip if you are not spraying a compatible material, i.e., water-based finishes in a gun that does not have a stainless steel tip and fluid passages.

It could also be that there's trash in your finish material, preventing the needle from properly seating in the tip, and it is therefore not closing correctly. Also, the fluid needle packing may be adjusted too tight or may need a little lubrication (Vaseline works fine).

If it's dripping from the tip, it's one of several problems.

The needle may be seizing in the packing after you release the trigger. Back off on the packing nut and smear some Vaseline on the needle.

The needle tip may be damaged (which is easy to do with Accuspray). Look at it closely and see if there are any marks on the very tip.

Finally, the needle may be mismatched to the nozzle.

The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor J:
I just found out why my gun began dripping. The two pins on the cup, which engaged the lugs on the gun, were bent slightly upward, preventing the locklever cam from pulling the cup and gun together (against the gasket). The gun would leak after a pull on the trigger was released, the pressure rises in the cup (HVLP), and voila, it leaked! Bad. After I bent the pins square to the cup and removed the extra gasket I previously tried as a fix, the gun stopped leaking. I use a Capspray commercial HVLP, and I didn't think I used too much force when I locked the cup to the gun, but I am less enthusiastic now. I don't like the cup they supply, as I have never had this problem with any other gun. Otherwise I like the Capspray.