1983/02/28 Caterpillar

3200 And 3400 Series Engines

SUPPLEMENT: 07/16/84

SERVICE MAGAZINE, FEBRUARY 28, 1983, PAGE 6. Put a mark through the article "Use Vacuum Tester For Quality Control Check Of Water Pump Seal" and make a reference to the article with the same title in this edition of Service Magazine.

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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.

To test a water pump seal, do the steps which follow:

1. Place either an FT1752 or FT1762 Fixture on the table of the vacuum tester. The FT1752 Fixture is used to test water pumps on all 3200 Series Engines. The FT1762 Fixture is used to test water pumps on all 3400 Series Engines. See Illustration 2.

2. Put the water pump on the fixture. On 3400 Series Engines, the water outlet will need to be sealed.

3. Move the air control knob to the down position.

4. Move the vacuum control knob to the down position. The vacuum gauge will read between 15 to 17 inches of mercury if the water pump seal is good.

Illustration 2.

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 the amount of vacuum and clockwise to decrease the vacuum.

Illustration 3.

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

A sudden drop in the amount of vacuum is an indication that the water pump seal needs to be replaced. If there is no vacuum decrease after five seconds, the water pump is good.

5. Move the vacuum control knob to the up position to break the vacuum and move the air control knob to the up position.

The VI-A Tester is available from: