Using the 9U-5383 Vacuum Tester {0774, 0781, 1000, 1100} Caterpillar

Engine:Commercial All

Engine:Truck All

Machine Engines: All

Marine Engine:with Turbochargers All

Pumper:All Utility Mounted

Introduction

The 9U-5383 Vacuum Tester is used to identify a poor seal between the intake and the exhaust valve and the valve seat after the cylinder head has been reconditioned.

Note: It is impractical to use the vacuum test to identify the minor leaks between the valve and the valve seat. The vacuum testing procedure should only be used to identify abnormally high leakage between the valve and the valve seat. An unavoidable amount of leakage between the valve and valve seat is acceptable.

The cylinder head must be cleaned before vacuum testing. The cylinder head must be completely assembled before vacuum testing.

The following specifications and equipment can be used to identify the gross leakers. Gross leakers are any combination of valve and valve seat that will not maintain 16 inHg or more.

9U-5383 Vacuum Tester

Illustration 1	g01388507

The 9U-5383 Vacuum Tester consists of a hand held vacuum pump and connecting parts.

For a complete list of all parts and fabricating dimensions, request a drawing of the FT1741 Tester Group .

Contact Information

Include your dealer code and the address so that your request will receive immediate attention.

The Sioux 1630 vacuum tester is suitable for use in all instances that have a required test vacuum of 18 inHg or less.

The optimal operating pressure is 90 PSI.

A leak has been detected when the gauge indicates a drop in vacuum.

An adjustment screw is provided on the top of the tool in order to vary the sensitivity of the gauge.

To set the adjustment screw for maximum sensitivity, follow these instructions.

1. Plug the inlet of the tester and pull the trigger for air supply.

2. Back out the adjustment screw until the maximum vacuum is obtained.

   Note: The maximum reading of the gun should be no less than 15 inHg.

   Refer to Table 1 in this instruction.

3. Turn the adjustment screw clockwise until a drop in vacuum of 1.0 inHg occurs.

   Note: The minimum set point is 14.0 inHg.

   Refer to Table 1 in this instruction.

4. Tighten the nylon jam nut in order to prevent any air leaks from giving a false leakage reading.

5. After the sensitivity screw has been adjusted, attach the correct adapter to the vacuum tester.

6. Then place the adapter over the valve which will be tested.

7. Hold the trigger for the air supply in the open position for a minimum of 15 seconds.

   Note: Make sure that the adapter is in full contact with the combustion area of the cylinder head.

8. If the gauge indicates a reading less than the test specifications for a given maximum capability of the gun, the seal of the valve to valve seat is not acceptable.

9. Apply slight pressure with a press on the top of the valve stem and test again.

10. If the gauge still indicates a low reading, the valve must be removed and the sealing surfaces must be inspected.

    It may be necessary to regrind the valve face and/or the valve seat. It may be necessary to lap the valve face and/or the valve seat.

Probable Causes of Leaks

• Bent valve

• Cracked valve face or valve seat

• Damaged valve face

• Damaged contact area of the valve seat

• Debris between valve face and valve seat

• Incorrect finish on valve face or contact areas of valve seat

• Improperly installed valve seat (incorrect Total Indicated Readout)

Specifications for Vacuum Test