Solo 4400203-P Complete Piston Sprayer Pump Assembly with Valve

Changing the piston was pretty easy following instructions. The most difficult part was putting the new assembly in making the "O" Ring sit good to seal tank. Ring is kind of loose fit and it will fold over the lip causing it to protrude out. Luckily for no sharp edges and with effort and cleaning off some of the lubrication ( PJ ) it went in and sealed up good. Works like a charm!!! My backpack is like new again. Great product!!!

Perfect replacement for the failed piston in my Solo 4 gallon sprayer. Despite the complaints in some reviews this is easy to replace if you have any skills at all. Just tap it in with a wooden block and be careful to not pinch the o-ring.

Works. No more leaks. My 425 sprayer was well over 15 years old.If you follow instructions that are included it should be pretty easy. Other than a couple additional 2x4s that I would recommend, they have the tools listed you need to replace the unit. I would suggest setting the frame on the additional 2x4s to gain a little more clearance when you drive the old unit out of the tank.Important to lubricate the new o-ring. It takes some pretty sharp raps to get the new pump ass'y to engage the tank opening. While seating the new pump ass'y its flange may not look like it seats completely down on the mating tank flange. Once you tighten the large clamp it should pull the two parts together. On mine I tightened the clamp screw until it ran out of thread.

fit perfect

The pressure control knob in the top of mine had broke off and there was no way of fixing that. So I was happy to find this! Was an easy fix. There’s plenty of videos on YouTube showing how to replace it. It also comes with good instructions too. The hardest part was knocking the old one out of the tank other than that it’s a simple install.

The media could not be loaded. I have two Solo pumps. I replaced the entire piece. And in the case of both, after several uses, the pressure chambers split into two as if they were two pieces. In the case of the ones that had the pressure chamber before, it was a single piece and that never happened to me. Now I have the doubt if the same thing will happen to me when I buy it again.

This replacement valve fixed the problem with my sprayer and made it just like new! I would highly recommend using a heat gun to heat up the plastic tank before you install this new valve assembly. I worked on it for about 45 minutes and could not get it to insert correctly into the plastic tank. After heating up the tank it went right in with no troubles.Great product to make a dead sprayer live again!!!

Solo pumps don't last as long as they should so replacing them is more than occasional. It usually takes more force than YouTube shows (I used a hydraulic press) but the replacement pump fits and works.