Push Rod Wear Caterpillar

Problem:

There have been some reports of premature wear on the push rods in some of these engines.

Solution:

1. If the valve lash is found to be greater than 0.010 inch above specifications during the initial valve lash inspection for the above affected engines, the push rods should be removed and inspected for wear at the ball end/lifter interface. If the ball end of the push rod is worn (see the illustrations), all of the push rods in that engine should be replaced (the lifters do not have to be replaced). All 12 replaced push rods should be tagged to show their position in the engine and returned to the following address:

NOTE: The initial valve lash adjustment is at 24 000 km (15 000 miles) or 5700 L (1500 US gal) of Fuel or 400 Service Hours or 6 Months with deep sump oil pan, and 17 700 km (11 000 miles) or 4150 L (1100 US gal) of Fuel or 250 Service Hours or 6 Months with shallow sump oil pan. The specifications for valve lash are 0.015 inch for the inlet valves and 0.025 inch for the exhaust valves. Therefore, if the measured valve lash is equal or greater than 0.025 in. for the intake valves or 0.035 for an exhaust valve, a push rod inspection is recommended.

2. If an engine in the above serial number range is being diagnosed for a rocker mechanism noise complaint or a single cylinder miss it is also recommended that a valve lash inspection be performed after applicable preliminary trouble shooting. Once again, if the valve lash is found to be greater than 0.010 in. above specifications, the push rods should be removed and inspected for wear at the ball end/lifter interface. If the ball end of the push rod is worn (see the illustrations), all of the push rods in that engine should be replaced (the lifters do not have to be replaced). All 12 replaced push rods should be tagged to show their position in the engine and returned to the address above.

3. If a set of push rods meets the above criteria and needs to be replaced, they should be replaced under normal warranty against the push rod part number (133-6379). Also, this TIB should be referenced in the claim story.

ILLUSTRATION 1.

Acceptable Wear, Burnishing on the entire ball end.

ILLUSTRATION 2.

Unacceptable Wear, grooves in the ball end and material displaced.

ILLUSTRATION 3.

Acceptable Wear, burnishing only on the tip of the ball end insert.

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