- Off-Highway Truck/Tractor:
- 793F AC (S/N: EMD1-UP)
- 793F (S/N: SND1-UP; SSP1-UP; RBT1-UP)
Introduction
The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below.
ReferenceSpecial Instruction, REHS7984, "Procedure to Update the Brake Control System on Certain 793F Off-Highway Trucks"
Problem
There are reports of multiple failures of the 390-6118 Gear Pump Gp . Failures have occurred between 500 to 2000 machine hours. Failure reports are showing that high temperature oil as the main failure mode. Failures of the 390-6118 Gear Pump Gp have occurred both on field replaced pumps and production built units.
Solution
Install and monitor two 8T-2822 Temperature Indicators per the attached rework procedure. If failure occurs replace with current part. The 390-6118 Gear Pump Gp was adaptable and effective in production with the machines that are listed in Table 1.
| Sales Model | Adaptable to Machines | Effective in Production Machines |
| 793F | (S/N: SSP1-985) | S/N:SSP986-UP |
| 793F AC | S/N:EMD1-UP | |
| 793F CMD | (S/N: RBT1-171) | S/N:RBT172-UP |
| 793F XQ | (S/N: SND1-131) | S/N:SND132-UP |
Note: If machines in the Adaptable to Machine column have been updated to the new 390-6120 Gear Pump Gp per Special Instruction, REHS7984, "Procedure to Update the Brake Control System on Certain 793F Off-Highway Trucks""" then this technical information bulletin applies to your machine.
| Required Parts | ||
| Qty | Part Number | Description |
| 2 | 8T-2822 | Temperature Indicator |
- Attach two 8T-2822 Temperature Indicators (104 – 132 C). Attach one Temperature Indicator on the brake actuation tank and one Temperature Indicator on the brake pump housing as shown in Illustration 1 and Illustration 2.
 | |
| Illustration 1 | g03728917 |
View of the mounting locations of the 8T-2822 Temperature Indicator | |
 | |
| Illustration 2 | g03728918 |
Detailed view of the mounting location of 8T-2822 Temperature Indicator on the brake pump housing | |
- Check Temperature Indicators at the end of each shift, directly after machine shutdown.
| NOTICE |
|---|
If Temperature Indicator temperature is 121° C (249.8° F) or greater, contact Caterpillar product support Tom Harris, +1 815-729-6703, or Jay Perry, +1 217-741-6733. |
Be prepared to provide the following information:
- VIMs download after temperature is observed at 121° C (249.8° F) or greater
- Hours on the pump
- Recent oil sample results
- Temperature observed at the tank and pump
- Pump serial number as shown in Illustration 3.
 | |
| Illustration 3 | g03728919 |
Typical view of the pump serial number | |