HARNESS AS-CONTROL 3060368 - Caterpillar

TECHNICAL INFORMATION BULLETIN MARCH 30, 2005
EXCAVATORS 330C (MCA, JAB),
330C L (KDD, GKX) EXCAVATORS
Component Code(s) 5073, 1387SUBJECT: THE SEAL ON THE SHAFT FOR THE FAN PUMP MAY LEAK ON CERTAIN
EXCAVATORS
PROBLEM:
The seal on the shaft of the fan pump may leak and blacken the color of the hydraulic oil. Due to heat, thermal degradation is a possible cause of the hydraulic oil becoming black. Two of the most common sources of extreme temperature in the hydraulic system are:
A hot spot from an external heat source that is in close proximity to the hydraulic system.
The implosion of entrained air bubbles that flow from the hydraulic tank into system components (pumps or valves) that increase the pressure of the hydraulic oil.
SOLUTION:
Inspect the oil cooler fan pump if excessive oil foaming in the tank or excessive hydraulic noise is present. Possible gas or engine oil leaks may be the cause of the blackened hydraulic oil. If necessary, replace the fan pump. Report and return the faulty fan pump to the Asia Pacific Division (APD) Service Group for engineering analysis.
The discoloration of hydraulic oil alone is not a measure of the condition of the oil. Make sure that the shaft of the oil cooler fan pump does not leak before replacing the hydraulic oil in the hydraulic system because the oil has become black.
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