1984/08/06 Caterpillar

3208, 3306 And 3400 Series Truck Engines

The water seal on rebuilt water pumps can be tested more easily with the VI-A Vacuum Tester, available from Industrial Air and Hydraulic, Inc. See Illustration 1. The tester is air-operated and uses venturi suction through a hole in the rubber table to test the water pump seal. The vacuum test method can be used as an effective quality control check for water pump seals. Any water pump can be tested when the inlet and outlet sides of the pump are sealed and a vacuum of 15 to 17 inches of Mercury is drawn in the impeller chamber. When this test is done, the customer can be sure that the rebuilt water pump has met nationally accepted quality control standards.

Illustration 1.

Procedure To Test Water Pump Seals

NOTE: Steps 1 and 2 are only for water pumps on 3200 and 3400 Series Engines. For water pumps on 3300 Series Engines, start with Step 3.

1. For water pumps on 3200 Series Engines, place FT1752 Fixture on the table of the vacuum tester. For water pumps on 3400 Series Engines, place FT1762 Fixture on the table of the vacuum tester. See Illustration 2.

2. Put the water pump on the Fixture. Water pumps on 3400 Series Engines, the water outlet will need to be sealed. Go to Step 5.

Illustration 2.

3. For water pumps on 3300 Series Engines, install an 8N5929 Plate and 8N5928 Gasket over the impeller.

4. Use a 6L7527 Adjustable Closure to seal the water pump inlet. Put the water pump outlet over the vacuum hole in the rubber table.

NOTE: To help make a seal between the water pump and the fixture or table, the pneumatic cylinder shown in Illustration 1 can be used to push down on the water pump. The water pumps used on Caterpillar Engines are heavy enough to make a good seal between the rubber-covered table or fixture to prevent air leakage.

5. Move the air control knob to the UP position.

6. Move the vacuum control knob to the UP position. The vacuum gauge should read between 15 to 17 inches of mercury.

NOTE: Since the tester operates from venturi suction, the amount of vacuum can be controlled with the air pressure adjustment screw. See Illustration 3. Turn the adjustment screw counterclockwise to increase or clockwise to decrease the amount of vacuum.

7. Move the vacuum control knob to the DOWN position. If there is no vacuum decrease for 5 seconds, the water pump is good. If there is a sudden drop in the amount of vacuum, the water pump seal needs to be replaced.

8. Move the vacuum control knob to the UP position to break down the vacuum lock.

9. Move the air control knob to the DOWN position to stop the air flow.

The VI-A Tester is available from:

Illustration 3.