C7.1 Industrial Engine Engine Valve Lash - Inspect Caterpillar

Illustration 1	g01334425
Cylinder and valve location (A) Exhaust valve (B) Inlet valve

Too much valve lash can cause broken valve stems, springs, and spring retainers. This will produce emissions in excess of the correct specification.

The hydraulic lifter will compensate for all normal wear of the components of the valve train.

Too much valve lash can be an indication of the following problems:

• Worn camshaft and valve lifters

• Worn rocker arms

• Bent pushrods

• Broken socket on the upper end of a pushrod

• Loose threaded insert on the rocker arm

• Issues with the hydraulic lifters

If the camshaft and valve lifters show rapid wear, look for fuel in the lubrication oil or dirty lubrication oil as a possible cause.

Valve Lash Check

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Accidental engine starting can cause injury or death to personnel. To prevent accidental engine starting, turn the ignition switch to the OFF position and place a do not operate tag at the ignition switch location.

1. Remove the valve mechanism cover. Refer to Disassembly and Assembly, "Valve Mechanism Cover - Remove and Install" for the correct procedure.

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Illustration 2	g01958182
Typical example

2. Remove the plug (1) from the cylinder block. Use Tooling (A) to rotate the crankshaft until the number one piston is at the top center position.

   Note: The number one piston may be on the compression stroke or the exhaust stroke.

3. Install Tooling (B) into the hole (X) in the cylinder block. Use Tooling (B) in order to locate the crankshaft in the correct position.

   Note: Do not use excessive force to install Tooling (B) . Do not use Tooling (B) to hold the crankshaft during repairs.

4. Check the rocker arms for engine valve lash. There should be no engine valve lash.

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Illustration 3	g02313353
Typical example One electronic unit injector is not shown for clarity.

5. If there is engine valve lash at any position the engine valve lash may be caused by a normal leakdown of the hydraulic lifter. Push the affected rocker arm (2) against the pushrod. Mount Tooling (C) with the pointer that is touching the top face of the rocker arm (2) . Monitor the rocker arm for movement. The rocker arm (2) should rotate as the pushrod is pushed up by the recovery of the hydraulic lifter. Once all motion has ceased test again for engine valve lash. There should be no engine valve lash.

6. Remove Tooling (B) from the crankshaft. Use Tooling (A) to rotate the crankshaft in a clockwise direction. The crankshaft should be rotated 360 degrees. Install Tooling (B) to the crankshaft.

7. Check the rocker arms for engine valve lash. There should be no engine valve lash.

8. If there is engine valve lash at any position the engine valve lash may be caused by a normal leakdown of the hydraulic lifter. Push the affected rocker arm (2) against the pushrod. Mount Tooling (C) with the pointer that is touching the top face of the rocker arm (2) . Monitor the rocker arm for movement. The rocker arm (2) should rotate as the pushrod is pushed up by the recovery of the hydraulic lifter. Once all motion has ceased test again for engine valve lash. There should be no engine valve lash.

9. If engine valve lash is found in any position, the most likely cause is that the hydraulic lifter has been purged of engine oil when the engine crankshaft has been rotated. This effect is temporary and the lifter will function correctly when the engine is in operation. If there is a large amount of lash, wear of valve mechanism components may have exceeded the adjustment range of the hydraulic lifter. Examine the valve mechanism components for excessive wear or damage. A final possibility is excessive wear or damage to the hydraulic lifters themselves. If other valve mechanism components do not exhibit excessive wear or damage, remove the hydraulic lifters. Inspect the hydraulic lifters for wear or damage.