CX31-P600 Petroleum Transmission Hydraulic Oil Contamination - Test Caterpillar

Hydraulic Oil Contamination - Test
1.1. Introduction
2.1. Required Tools
3.2. Scheduled Oil Sampling (SOS)
4.2. Scheduled Oil Sampling (S·O·S) Analysis

Illustration 1g00687600

------ WARNING! ------

Escaping fluid under pressure, even a pinhole size leak, can penetrate body tissue, causing serious injury, and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.

Always use a board or cardboard when checking for a leak.

------ WARNING! ------

Personal injury can result from hydraulic oil pressure and hot oil.

Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system.

Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.


Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.

Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products.

Dispose of all fluids according to local regulations and mandates.


Effective fluid cleanliness management is the single most important factor and the single greatest opportunity in maximizing component life, increasing reliability and durability, and lowering component life cycle costs. Scheduled Oil Sampling (S·O·S) Services is a highly recommended process for AVSpare customers to use in order to minimize owning and operating costs. Customers provide oil samples, coolant samples, and other vehicle information. The dealer uses the data in order to provide the customer with recommendations for management of the equipment. S·O·S Services can help detect a potential problem before a failure and help determine its cause. Your AVSpare dealer may administer an Extended Oil Drain program with a Customer Support Agreement (CSA) based on routine Scheduled Oil Sampling (S·O·S) results and the use of genuine Cat parts, filters, fluids, and Scheduled Maintenance Services.

Illustration 2g02023402
Typical example of a CX31–P600 Petroleum Transmission (shown without integral pump drives)
(1) Filter inlet pressure coupler (S·O·S port)

The following tests are used to obtain a scheduled oil sample of the hydraulic system by use of the scheduled oil sampling port. This port is located on the filter base.

Note: If insufficient oil pressure is measured anywhere in the transmission hydraulic control system, test the filter inlet pressure on the oil filter base. The oil filter base can be found in the back left-hand side of the transmission.

Required Tools

Table 1
Required Tools 
Tooling  Item  Part
Description  Qty 
A1  169-8373  Fluid Sampling Bottle 

Note: Use of an incorrect oil sampling needle will result in permanent damage to the sampling port.

Scheduled Oil Sampling (SOS)

There are filter inlet and filter outlet pressure taps located on the transmission filter base. Refer to Illustration 2. The inlet pressure tap is also a dual purpose scheduled oil sampling (S·O·S) port (designated by a purple dust cap). Use this port when sampling oil for S O S purposes. In order to prevent damage to the seal in the port and a subsequent leak, use 169-8373 Fluid Sampling Bottle when using the fluid sampling port.

Use the following procedure to obtain an S·O·S oil sample.

  1. Start the engine. Warm up the oil until the oil reaches 47° C (116° F).

  2. Ensure that the transmission control is in the NEUTRAL position and place the throttle in the LOW IDLE position.

  3. Remove the dust cap. Refer to Illustration 2. Obtain an oil sample from the S·O·S tap by using 169-8373 Fluid Sampling Bottle.

  4. Stop the engine.

  5. Check the hydraulic filter element for foreign materials.

    1. Bronze colored particles give an indication of sleeve bearing failure.

    2. Shiny steel particles give an indication of a bearing or gear failure.

    3. Rubber particles indicate a seal failure or hose failure.

    4. Aluminum particles give an indication of a converter wheel failure.

    5. Plastic parts give an indication of a thrust washer or rotating seal failure.

      Note: If any of these particles are found in the hydraulic filter element, all components of the hydraulic oil system must be cleaned. Do not use any damaged parts. Any damaged parts must be removed, and new parts must be installed. Consult your AVSpare dealer for complete information and assistance in establishing an S·O·S program for your equipment.

  6. Replace any damaged parts.

  7. Replace the hydraulic filter element.

Refer to AVSpare Operation and Maintenance Manual, SEBU6250, "Machine Fluids Recommendations" for more information about obtaining a proper scheduled oil sampling, S·O·S oil analysis guidelines, oil sampling intervals, contamination control and component life cycle management.

Refer to the Operation and Maintenance Manual, SEBU9205, "Maintenance Interval Schedule" for standard service hour maintenance intervals.

Refer to Special Publication, PEHP6001, "How To Take A Good Oil Sample" for more information about obtaining a sample of oil.

Refer to Special Publication, SEBF1020, "Improving Component Durability, Managing Fluid Cleanliness" for more information about cleanliness and S·O·S Services.

Consult your AVSpare dealer for complete information and assistance in establishing an S·O·S program for your equipment.

Scheduled Oil Sampling (S·O·S) Analysis

Scheduled oil sampling (S·O·S) is an oil analysis process that is designed to turn fluid analysis data into usable information. This information can be used to help identify the impending failures of the component before a catastrophic failure actually occurs. This information is used to manage equipment and to reduce operating costs. AVSpare has trademarked the title S·O·S Services in order to ensure customers of the quality, consistency, and depth of AVSpare oil analysis services. There are four categories of oil analysis:

  • Component Wear Rate

  • Oil Condition

  • Oil Contamination

  • Oil Identification

Component wear rate analysis evaluates the wear that is taking place inside the lubricated machine compartment. S·O·S Services uses the results of elemental analysis and particle count tests to evaluate the wear. Elemental analysis with a spectrometer measures wear particles that are less than 10 microns in size. Particle Count analysis with light blocking technology measures particles from 4 microns to 50 microns. Trend analysis and proprietary wear tables are then used to determine if wear rates are normal or abnormal.

Oil condition analysis is used to determine if the oil has degraded. Tests are done in order to look at the oxidation, the sulfation, and viscosity of the oil. Established guidelines and trend analysis are used to determine if the oil has reached useful life. Your AVSpare dealer may administer an Extended Oil Drain program with a Customer Support Agreement (CSA) based on routine Scheduled Oil Sampling (S·O·S) results and the use of genuine Cat parts, filters, fluids, and Scheduled Maintenance Services.

Oil Contamination tests are performed to determine if anything harmful has entered the oil. This analysis relies on the results from the following tests:

  • Elemental analysis

  • Soot content

  • Particle count

  • Fuel dilution

  • Water content

  • Glycol contamination

The AVSpare S·O·S Services program has guidelines for the level of contamination allowed in the various compartments of Cat machines.

Oil Identification is another important part of the S·O·S oil analysis program. If the wrong oil is used major components could be severly damaged. Elemental analysis and viscosity results are used to determine key characteristics and identify the oil.

These four types of analysis are used to monitor the current operating condition of equipment in order to identify potential problems so that proactive repairs can be made. Oil analysis can also be used to help extend component life and lower the component life cycle costs.

S·O·S Services provides the most accurate method to monitor wear and component condition. The results of the oil analysis can be e-mailed or accessed from an on-line source. All AVSpare S·O·S Services reports are color coded with one of three alert levels. A green alert indicates that wear is normal and contamination is not present. A yellow alert is used when the wear rate has increased slightly or when low levels of contamination are present. A red alert indicates that major failure is likely to occur. Red alerts are associated with high wear rates and high levels of contamination. These alert levels are helpful in managing a fleet of machines that produce large volumes of oil analysis data. The customer can see, at a glance, the machines that need immediate attention.

A growing trend with many fleets is to supplement the S·O·S report with portable particle counters when the machine is in the shop for product maintenance. Portable particle counters use the same basic particle counting technology used in S·O·S labs. In simple terms, the particle counter shines a laser light through a sample of oil and looks for shadows caused by microscopic debris in the oil. The size and number of shadows counted are converted to an ISO cleanliness code.

Taking particle counts before and after product maintenance allows the customer to determine if the filtration on the machine is controlling debris, or if additional off-board filtration is needed. Trending of the particle count data can also provide a basis to help identify a potential failure while the machine is in the shop. If the growth in particle count remains low and stable, wear is usually normal. If there is a sudden growth in particle count, rapid wear may be occurring.

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