Ask the Expert Question-and-Answer Archive

by Ron Joseph

September, 2002

Leaking Spray Gun

Q. I have a De Vilbiss JGA 510, suction-feed paint gun with a drip -free lid, just rebuilt with new needle and fluid tip and rebuild kit. Cannot seem to stop it from giving a surging fluttering type of spray. I've gone over all possible airleaks and have retightened parts and still does not work. Could you help me with this as I reached the end of my rope.

A. The only thing I can think of is that the seal between the cup and the lid has a leak and that when the suction builds up to a certain level, air is sucked from the outside into the cup, thus ruining the vacuum in the cup. Have you replaced the gasket under the lid? Have you checked that the lid or the edge of the cup are not deformed in any way? I have seen this problem when a cup was dropped and there was a small nick on the edge.

Have you asked the folks at DeVilbiss? (www.devilbiss.com) They have put together a comprehensive chart of all the problems that are often experienced with their spray guns.