Boom, Stick, Bucket, and Blade Hydraulic Cylinders May Leak on Certain 303.5E2, 304E2, and 304.5E2 Mini Hydraulic Excavators {5113, 5456, 5457, 5458} Caterpillar

Mini Hydraulic Excavator

303.5E2 (S/N: JWY1-UP)

304.5E2 (S/N: FXT1-UP)

304E2 (S/N: ME41-UP)

Reference: Disassembly and Assembly, UENR5592 , "Mini Hydraulic Excavators Machine Systems"

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.

Problem

Boom, stick, bucket, and blade hydraulic cylinders may leak on Mini Hydraulic Excavators. Rod wiper seal may need to be more robust to prevent damage due to contamination. Debris may reach the U-Cup seal, causing failure of the seal. Seal failure may cause cylinder drift and external leakage.

Solution

Illustration 1	g06426310
Hydraulic cylinder.

Caterpillar is aware of this problem, but an interim repair has not been defined. When replacing seal kit, replace failed parts with a more robust rod wiper seal and U-CUP seal.

Note: Do not use the rod wiper seal and U-Cup seal in the seal kit.

Refer to Table 1 for correct required seals that are more robust. Refer to Table 2 for the correct seal for your machine.