Root cause can be determined due to the repetitive nature of the movement. Component replacement and effectiveness is considered "High Confidence" for problem resolution.

The procedures that follow have been developed to help determine the root causes of boom or stick drop, implement drift, or a powered movement of any implement. These procedures address drop, drift, and powered movement problem conditions.

If a field call is received or a machine is brought in to the shop for boom or stick drop, implement drift, or a powered movement of any implement, the dealer technical services should be made aware of the machine Product Identification Number (PIN), the service hour meter reading, and the problem condition. The information can then be communicated to Caterpillar Service Engineering as soon as possible.

POWERED MOVEMENT NOTE: If powered movement of any implement is the problem, the surface conditions of the main valve spool and fit are critical immediately after the reported movement. The spool fit and/or interference should be checked by a technician within 5 minutes of the report, where and when practical. Unless the spool condition indicates otherwise, the data should be compared with the stem bore fit after the machine has "cold soaked" overnight. If the known hydraulic circuit has malfunctioned as a powered movement, operate the machine after the cold soak period. Make sure to operate the machine in a safe manner and in an operating area that is free from objects. Operate the machine at straight travel until a hydraulic temperature reading of three bars or 50?C (122?F) is achieved. During this period, the operator should not operate linkage and swing functions. When the desired temperature is achieved, operate the questionable linkage function and/or travel function. If the function repeats the powered movement or if the function does not repeat the powered movement, shut down the machine in a safe manner and check for spool(s) that stick in the bore of the hydraulic control valve. This check should be performed within 5 to 10 minutes. Release stored hydraulic energy and remove the stem end caps from the main hydraulic control valve. Try to remove the stems. If they are difficult to remove, note the main valve function and contact your Technical Communicator. During operation try to identify if the function can be corrected or stopped, with the hydraulic activation control lever in the LOCKED position, or with the engine stopped. Results from either test should be communicated to your Technical Communicator. Undersized main valve stems are available from the factory in order to correct the interference between the bore in the main valve and the stem.

Check with the oil lab for the history of previous hydraulic samples from the machine. Regardless of previous history, replace the current filters with a new pilot filter, case drain filter, and main hydraulic filter(s). If wear metals are high or within specifications, proceed to Step 1 (A) or Step 1 (B).

BOOM AND/OR STICK DROP NOTE: If boom or stick drop is identified, replace the line relief valves for the boom UP, stick IN, and stick OUT functions with a new 239-8920 Relief Valve in 345B and 345B II Excavators.

1.(A) If a field technician arrives at the job site and the customer?s operator is running the machine with the reported problem reoccurring, instruct the operator to place the hydraulic activation control lever in the LOCKED position. If this does not correct the problem, turn the key switch to the OFF position. With warm machine hydraulics, obtain two hydraulic oil samples. Obtain an oil sample from the live oil sample port (at the pilot filter) and an oil sample from the hydraulic tank. The samples should be taken regardless of previous samples taken or previously reported SOS analysis indicating high particle count, or a significant increase from the previous samples collected. As a guideline for International Standards Organization (ISO) reported oil contamination levels, a 2-point rise over the trended levels should be considered as a level where an intervention should be taken to understand the contamination source and/or related problems with the oil and/or the machine?s equipment. At the time of rework and/or preventative maintenance procedures on a particular machine, an Excavator target of an ISO 16/13 should be established before the machine is returned to work.

(B) If a field technician operates the machine attempting to duplicate the problem, place the hydraulic activation control lever in the LOCK position in order to stop the problem condition. If placing the hydraulic activation control lever in the LOCK position does not stop the problem, turn the engine start switch to the OFF position. Oil samples should be obtained from the live oil sample port (at the pilot filter) and from the hydraulic tank after the machine has been warmed up. Obtain the samples even if the previous samples indicated high particle count, or a significant increase from the previous oil samples collected. As a guideline for (ISO) reported oil contamination levels, a 2-point rise over the trended levels should be considered as an alarm level where additional actions should be taken to understand the contamination source and/or related problems with the oil and/or the machine?s equipment.

NOTE: The machine should only be operated with sufficient area in order to let any of the complaint conditions occur without causing damage.

The major components (main control valve, main hydraulic pump, hydraulic motors, hydraulic cylinders) need to be disassembled, cleaned, and resealed if a major component fails. Depending on the failure, all components may not need to be disassembled and cleaned. At a minimum, the hydraulic cylinders should be cleaned and new seals should be installed.

There are several publications that describe procedures for flushing the hydraulic system. Refer to Contamination Control Guidelines, SEBF8447, "Procedure for Kidney Looping Excavator Hydraulic Oil" and Special Instruction, SMHS6936, "Procedure To Flush And Clean Excavator Hydraulic Systems". The procedure that follows and SMHS6936 are similar. Review each of the documents for a basic understanding of the procedures. The clean out hydraulic filters for flushing the system and the high efficiency filters are listed in Table 2.

Any hydraulic pump failure is serious, but some subjective judgment must used in order to determine how the failure occurred. If the pump pistons or the retaining ring for the pump swash plate failed, small metal pieces (BB to marble size) will be evident and the pump rotating group probably operated for some time prior to machine shutdown. The small pieces are probably downstream in the hydraulic system and in other major components. If only large pieces are evident and the pieces can be accounted for, it is less probable that debris has been pumped through the system.

If the pump failure produced small metal particles, the hydraulic lines should be disconnected at their lower end. Drain the hydraulic lines at each major component. Hydraulic lines on the top of the boom, lines to the travel motors, and lines to the oil cooler core are typical of the lines to major components. Make sure to inspect the oil that is drained out of the lines as they are disconnected. The drain oil should be collected in clean containers and labeled as to the source on the machine. Close inspection will indicate the severity of metal particles in the system and the magnitude of system contamination. Disassembly and flushing of the line is not sufficient if the oil shows a major particle content on a clean white towel. The associated major component must also be removed, disassembled, and thoroughly cleaned before reassembly.

If the oil on a clean white towel has minimal metal contamination present, remove the hydraulic line and flush it clean before reassembly.

Continue with the flushing procedure that follows:

After repair and reassembly of the hydraulic pump, change the hydraulic filters on the machine. Install a set of high efficiency cleanout filters on the machine.

Use a 127-8781 Transfer Cart Group. Refer to Contamination Control Guidelines, SEBF8279, "Procedure for Operating Caterpillar Filter Carts". Connect the cart to the machine by placing the suction tube in the opening of the hydraulic tank. Extend the suction tube to the bottom of the tank. Place output hose of the portable oil transfer filter cart in the opening of the hydraulic tank. When operating correctly, the suction hose should collect oil from the bottom of the tank, filter the oil through the cart, and return the filtered oil to the tank.

Do not start the machine. Continue to operate the filter cart for 15 minutes.

Start the engine and idle the engine with the engine speed dial on position "1". Move all implements to the fully extended position. The boom should be fully extended UP, the stick IN, and the bucket should be fully CLOSED. Operate the filter cart for 15 minutes.

Keep the machine running. Fully retract all of the implements. The boom should be fully retracted DOWN, the stick OUT, and the bucket should be fully OPEN. Operate the filter cart for 15 minutes.

Prepare the machine and the boom and stick linkage for bypassing all hydraulic cylinders, travel motors, and swing motors.

Note: This assumes that none of the listed components have had a catastrophic failure.

Disconnect the hydraulic lines from the hydraulic cylinders, the travel motor, and the swing motor(s). Connect the ends of the hydraulic lines or install hose loops in order to close the hydraulic circuit. The closed loop allows the oil to continuously circulate. Turn the engine speed dial to position "10". Activate the boom UP circuit for 30 seconds. Active the boom DOWN circuit for 30 seconds. Repeat the cycle for 5 cycles. Perform 5 cycles for the stick. Perform 5 cycles for the bucket. Repeat 5 cycles for the boom. Reconnect all the hydraulic lines to their respective ports. Prepare the machine for Step 7.

Swing the machine to the side and lift the left track off of the ground. Activate the left travel and allow the track to run for 5 minutes at low speed. Run the track at high speed for 5 minutes. Position the both tracks on the ground. Swing the machine to the opposite side and lift the right track off of the ground. Activate the right travel and allow the track to run for 5 minutes at low speed. Run the track at high speed for 5 minutes. Position the both tracks on the ground.

Note: Operate both travel motors in the forward and the reverse directions.

The swing from left to right will exercise the swivel and should aid in the purge of the swing circuit. Target a total of 10 minutes for cycles from left to right and from right to left in order to move the oil through the cleaning process.

Cycle the boom UP and boom DOWN for a total of 15 minutes. Alternate these actions with other hydraulic circuits every 5 minutes for a total of 15 minutes on every cylinder for the boom, stick, and bucket systems.

Shut down the machine. Remove the high efficiency cleanup filters from the machine. Cut the filters open for inspection. The filters should contain significant debris if the hydraulic system had been previously contaminated.

Install new standard hydraulic system filters.

Allow the machine to operate normally for 10 hours. Sample the hydraulic oil after 10 hours of operation. If the SOS sample indicates normal elements and particle counts, allow the machine to continue operating. If the SOS sample indicates abnormal elements and particle counts, operate the machine for 10 hours and obtain another sample. The sample will typically be within the acceptable category. If the SOS sample continues to indicate a concern, it may be necessary to repeat the filter cart procedure.

Note: The hydraulic clean out filters are ONLY for flushing and cleaning up the hydraulic system of a machine. The clean out filters should NOT be left in a machine that is returned to normal operation.

High efficiency filters should be used as standard filters for severe conditions and/or breaker applications when the machine is returned to the customer. Reference Service Magazine, SEPD0551, 20 November 2000, "A New Hydraulic Oil Filter Element Is Available for Extreme Dust Conditions", and Service Magazine, SEPD0691, 14 July 2003, "The Hydraulic Pilot Oil Filter Is Improved".

Note: The customer should be informed that the use of ONLY high efficiency main hydraulic filters will change the current 1000 hour change interval to a 250 hour change interval. SOS oil samples should be taken along with the filter change. The pilot filter service interval will remain the same.

The high efficiency filters will help monitor the condition of the oil in the hydraulic system. The customer can return to using standard filters and maintenance intervals after 500 hours to 1000 hours of monitoring the system if the oil samples indicate a clean system.