Diaphragm Removal

Figure 1. - Diaphragm Assembly.

To remove and repair the diaphragm:

1: Remove Paint Pump Block (3) using a 6mm allen wrench to remove the 4 Bolts (1).  Save Washers (2)

(If you are not replacing the insert ring skip to step 3)

2: Remove the Insert Ring (4) in the bottom of the paint pump block and replace with new ring

3: When housing is removed, Diaphragm (5) can be lifted out of the pressure vessel in one piece.  If the diaphragm does not come out easily, carefully pry it out as best you can.  Be sure to take extra care not to damage the grooves under the edge of the diaphragm membrane.

Tip: Before installing the new diaphragm. To avoid having to bleed the air bubbles from the hydraulic system later; before installing the new diaphragm pour an ounce or two of hydraulic fluid into the upper hydraulic chamber  (area you will be inserting the diaphragm into) before pressing the diaphragm into place.  A little oil will squirt out when you press the diaphragm into place using this method.  The advantage is the system will usually not need bleeding.

Re-Assembling Paint Pump Block

1. Before installing the 4 paint pump block bolts, it is recommended to put Anti-Seize on the threads first.  After the Anti-seize lubricant is put on; re-install the bolts, making sure to install the lock washers first, using a 6mm hex setscrew bit on a torque wrench.

2.Tighten opposite screw gradually in turn as shown.  Tighten screw evenly to 15 foot pounds.  Do not over tighten.

Tighten screw A first, then B, then C, then D.

Figure 2. - Tightening sequence for paint pump screws.   Tighten only to 15 ft lbs. torque, in the sequence shown.

Tip: If you do not own a torque wrench, many national auto-parts stores have loaner torque wrenches you can use for a deposit.  A torque wrench is recommended is to ensure you are applying equal torque to the bolts.  When torqueing the bolts down, the head is actually pressing/cutting groves into the new diaphragm.  Equal pressure is essential for proper function of the diaphragm pump.  Uneven torque can allow hydraulic fluid to force its way out from under the diaphragm.  It is also a good tip to go back and recheck this the torque on the bolts after the first 10 hours of usage after replacing the diaphragm.

3. After pump block is tightened, the hydraulic system will need to be bled.  See Bleeding Hydraulic System in your operator's manual.  (many manuals do not have this info so general info will follow below)

When checking unit before servicing, or for testing after service, always bleed the hydraulic system first. (after checking hydraulic fluid level).

General-How to bleed the hydraulic system of air bubbles after servicing.

A: Turn pressure control knob all the way counterclockwise, turn the priming knob to prime mode, and let the spray run a few minutes. (up to 5-8 minutes)  It is sometimes helpful to turn the On-Off switch On and Off to assist in bleeding.

B. Now turn pressure control knob clockwise to prime the pump.   When sprayer is primed, paint will come out of the return tube.  This may take 2-3 minutes.  If sprayer does not prime, turn pressure control knob counterclockwise and repeat procedure.

Tip:  No moving parts touch the diaphragm, it is actually the hydraulic fluid inside the upper hydraulic chamber that is moving the diaphragm up and down rapidly.   This is why bleeding out the trapped air bubbles  is needed.  And also the reason use of Wagner/SprayTech brand hydraulic fluid is the only brand we recommend due to is a NON- detergent and a 10 weight.  Many off brand hydraulic fluids contain detergent which the detergents will bubble on its own and cause problems.

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Last modified: 04/02/05

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