AXLE AR-FRONT 3814370 - Caterpillar

Introduction
The problem that is identified in the technical information bulletin that follows does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below.Problem
Illustration 1 g02998357
The 296-0738 Hoist Cylinder Gp (1) that is part of 331-1801 Hoist Lines Gp is making a high pitch whistling noise when the body is in the last 457 to 610 mm (18.0 to 24.0 inch) of upward or downward travel. This noise may be noticed when the truck is cold or after the truck has been thoroughly heat soaked (three or more rated payload cycles).Solution
Hoist system testing and evaluation are taking place in both the factory and the field to determine the cause of the noise. Results from the testing and evaluation has identified that the noise emanates from the hoist cylinder only. The problem is not present on all trucks and is only a nuisance problem.The performance of the truck and the durability of the hoist system is not affected by a noisy hoist cylinder. In the field, the noise goes away after the initial 250 to 300 hours of operation. This information leads to the assumption that the noise is due to the components in the hoist system requiring a wear in period.Caterpillar is aware of this problem, but an interim repair has not been defined. We are seeking help in establishing the wear in period. Submit feedback to the questions below via email to Jason Brunner at Brunner_Jason_G.
When is the noise initially noticed? (Machine Hours and Load Count)
Is the noise present every cycle or periodic?
Is the sound less noticeable as the machine hours and load count increase? (Machine Hours and Load Count)
When is the noise no longer heard or noticed? (Machine Hours and Load Count)