C175 Petroleum Engine Caterpillar

Introduction

Use this procedure for adjusting the Hydraulic Lash Adjusters (HLAs) on C175 diesel engines.

During service, oil is not supplied to the HLA low-pressure chamber. Therefore, events such as excessive barring, multiple HLA adjustments, and removing / reinstalling rocker mechanisms (without backing off adjusting screw), may cause the HLA to purge off oil.

If this occurs, the HLA will not be able to refill the high-pressure chamber, therefore the HLA will feel soft during adjustments. Refer to the following Testing and Adjusting procedure to refill the HLA and readjust. If the HLA is not refilled prior to start-up, the HLA will take longer to fill due to air entrainment. Therefore, you will hear valve train noise for a longer period as the HLA refills.

Required Tools

Valve Lash Adjust Preparation

1. Ensure that the number 1 piston is at the top center position. Refer to Testing and Adjusting, "Finding the Top Center Position for the No. 1 Piston".

2. The number 1 piston must be at the top center position of the correct stroke. Adjust the valves according to the chart: Refer to Testing and Adjusting, "Crankshaft Positions for Fuel Injector Adjustment and Valve Lash Setting".

   Note: Keep all parts clean from contaminants. Contaminants may cause rapid wear and shortened component life.

3. Remove the valve covers. Refer to Disassembly and Assembly, "Valve Cover – Remove and Install".
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   Illustration 1	g03896611
   (1) Rocker bolt (2) Rocker shaft

4. Remove rocker shaft bolts (1) from the rocker arm base.

5. Remove rocker shaft assembly (2) from the rocker arm base.
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   Illustration 2	g03896612
   (3) Hydraulic lash adjuster (4) Lifter

6. Remove HLAs (3) from the cup of valve lifters (4).

Valve Lash Check and Adjust

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Illustration 3	g03896613
(5) Adjusting screw nut (6) Adjusting screw

1. Loosen valve adjusting screw nuts (5).

2. Loosen adjusting screw (6) until push ball end contacts rocker arm.

   Note: This action is a best practice and acts as a reminder the HLA needs set each time.

3. There are six steps to ensure that the HLA is properly filled with oil:

   • Compression test

   • Oil fill

   • Valve depressing tool

   • Repeat compression test

   • Repeat oil fill

   • Keep HLA vertical
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   Illustration 4	g03890206

4. Depress the top of the HLA, refer to Illustration 4. If the resistance is "spongy" go to Step 5. If the HLA is "solid" go to Step 9.
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   Illustration 5	g03890207
   (A) 494-5411 Disposable Syringe (B) 494-5412 Reusable Probe

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   Illustration 6	g03890208
   (A) 494-5411 Disposable Syringe (B) 494-5412 Reusable Probe

5. Fill the HLA inside the piston with clean engine oil using the disposable syringe (A) and reusable probe (B) until full and oil accumulates in the cup. Refer to Illustration 6.
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   Illustration 7	g03890210
   (C) 494-5414 Valve Depressing Tool

6. Insert the valve depressing tool (C) into cup of the HLA. Refer to Illustration 7.
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   Illustration 8	g03890211
   (C) 494-5414 Valve Depressing Tool

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   Illustration 9	g03890318
   (C) 494-5414 Valve Depressing Tool

7. Use the HLA valve depressing tool (C) to open check valve and compress the piston to purge air from the chamber. Will take approximately 2 to 3 pumps to purge air. Refer to Illustration 9.

8. Check the HLA for "sponginess", refer to Illustration 4. The HLA should be solid (full). If still "spongy" return to Step 5.

9. Once the HLA feels solid, the HLA is full of oil. Fill the chamber inside the cup once again with oil until oil comes out into the cup.

10. Keep the HLA in a vertical position and place back into followers.
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    Illustration 10	g03896631
    (1) Rocker bolts (2) Rocker shaft (3) Hydraulic lash adjuster (5) Adjusting screw nut (6) Adjusting screw

11. Install rocker shaft assembly (2) onto the rocker arm base.

12. Place rocker shaft assembly (2) in position on the rocker arm base. Make sure that the rocker arms and HLAs (3) are aligned. Install bolts (1).

    Torque bolts ... 200 ± 30 N·m (148 ± 22 lb ft)

13. Run down exhaust adjusting screws (6) until the adjusting screws "touch". With an allen wrench, adjust each adjusting screw as a "touch" plus one full turn (360 degrees).

    Torque nut ... 120 ± 15 N·m (89 ± 11 lb ft)

14. Run down intake adjusting screws (6) until the adjusting screws "touch". With an allen wrench, adjust each adjusting screw as a "touch" plus two full turns (one full turn is 360 degrees).

    Torque nut ... 120 ± 15 N·m (89 ± 11 lb ft)

15. Install the valve covers. Refer to Disassembly and Assembly, "Valve Cover – Remove and Install".

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