3608 Engine Caterpillar

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Personal injury or death can result from the engine starting. The engine can start and injure persons working on or near the engine. Be sure the engine cannot be started while service work is being performed. This is very important when the engine is equipped with an Automatic Start Stop System. On engines equipped with an air starting system, close the air supply valve to the air starting motor before service work is begun.

Illustration 1	g00754292

The crankshaft must be able to rotate in order to find the crankshaft's correct operating position within the cylinder block. The crankshaft's fore and aft movement is limited by thrust plates that are located at the number nine main bearing. The specification for the thrust of the crankshaft is a minimum of 0.2032 mm (0.008 inch) and a maximum of 0.6096 mm (0.024 inch).

The thrust of the crankshaft must be checked when one of the following events occur:

• The engine or the generator is relocated.

• The thrust plates are replaced.

• Part of an engine overhaul

• Requirements of the maintenance system

This test can also be used as the first check to confirm a bearing failure that is indicated by a high aluminum content in a scheduled oil sampling (S·O·S) report.

In order to check the thrust of the crankshaft, refer to Illustration 1. Conduct this test with the 3608 at room temperature:

1. Remove the crankcase side covers from one side of the engine at the numbers five, six, and seven cylinder positions.

2. Start the electric prelube pumps for the engine and the generator.

3. Position the dial indicator and mount the dial indicator on any convenient location. In order to check the fore and aft movement of the crankshaft, place the dial indicator on the crankshaft counterweight of the number five cylinder.

4. Use the manual barring device in order to rotate the crankshaft. Rotate the crankshaft until a pry bar can be inserted between the counterweight for the number six cylinder and the cylinder block face for the number seven main bearing.

   Note: It may be necessary for one person to maintain pressure on the pry bar while another person is zeroing or reading the dial indicator. This is due to the spring effect of the crankshaft and the flexible coupling. No more than one person should use force on the pry bar.

5. Pry the crankshaft forward and then zero the dial indicator.

6. Rotate the crankshaft until the same pry bar can be inserted between the counterweight for the number seven cylinder and the cylinder block face for the number eight main bearing.

7. Check the zero on the dial indicator.

8. Pry the crankshaft rearward and at the same time read the indicator movement.

9. Record the thrust of the crankshaft in the engine history file.