VSS 10-12
SERVICE GUIDE FOR REPLACING PUMP DIAPHRAGMS
1. Drain Crankcase Oil – drain pump crankcase by removing the oil drain plug located
at the bottom of the pump, also remove the oil fill cap or plug.
Note: On older pump models that do not have the oil drain plug, oil will need to be
drained after the head diaphragm and piston sleeve have been removed.
Note: When re-installing piston sleeves, the oil holes must always be aligned
parallel with the pump crankshaft.
2. External Manifold Removal – if your pump has external manifolds, they must be
removed prior to head removal.
3. Head Removal – remove the head bolts, then, remove the pump heads, which may
require some “light” prying.
4. Diaphragm Removal – turn the crankshaft to bring the piston up to the top of its
stroke, remove the diaphragm bolt and washer, and remove the diaphragm.
5. Crankcase Cleaning – to properly clean the crankcase, remove the piston sleeves
and wash the crankcase with a parts-washing solution or equivalent. Before re-
installing the piston sleeves, apply a light coating of oil to the pistons and sleeves.
Note: Make sure the oil holes in the piston sleeve are aligned parallel to the pump
crankshaft.
6. Installing New Diaphragms – install the diaphragm bolt and washer into the new
diaphragm. Install this assembly to the piston with the flat side of the diaphragm
down. Use blue thread locker or equivalent on the diaphragm bolt. Tighten the
bolts to the recommended torque specs. Rotate the crankshaft to bring the piston
and diaphragm to the bottom of its stroke and then seat the outside edge of the
diaphragm into the pump body.
7. Installing Head – it is very important to ensure that the check valves are installed
correctly when reinstalling the pump head. There are two valves for each cylinder;
one valve lets the solution into the head, the other valve lets the solution out of the
head. Tighten the pump head bolts to the recommended torque specs.
8. Installing Pulsation Dampener Diaphragm – bleed off the air in the chamber and
remove the cover bolts, cover, and diaphragm. Install the new diaphragm with the
dome down. Reinstall the cover and tighten the bolts to recommended torque
specs. Recharge the pulsation dampener with compressed air to 20% of the
pumps operating pressure.
9. Refilling Pump Crankcase – check the oil drain plug, making sure that it is installed
in the crankcase. Fill the pump with UDOR LUBE premium pump oil or SAE 30 or
40-weight non-detergent oil to the recommended mark on the oil sight glass/gauge,
about halfway on the oil sight glass/gauge. Rotate the crankshaft while filing to
eliminate air pockets.
10. Initial Start Up – run the pump for five minutes under no load conditions. This will
evacuate any remaining air pockets in the crankcase. Turn the pump off and re-
check oil level. Refill as necessary to proper oil level.
IMPORTANT During initial startup, monitor the oil color. If it turns milky white, the
diaphragms were not seated or installed correctly.
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