3 keys to maintaining automatic transmissions

David M. Sluder
Posted on February 1, 1998

Premature failure of your automatic transmissions can be minimized through proper spec'ing, preventive maintenance and technician training. By including these items in your maintenance program, it will help to ensure that you realize the maximum potential of the transmission. First step is right spec
For any piece of equipment to perform as it was designed, planning is required. The automatic transmission is no exception to this rule. The first step to prevent premature failure is to ensure that the right transmission is included in the purchase specifications. I will further clarify this statement with the following statement: Cheapest is not always best. By including in your specs a transmission that is not continually taxed to its limit, you can avoid premature failure. This will result in reduced cost over the life of the vehicle. Pay attention to intervals
The transmission oil level should be checked at the intervals specified in the vehicle operator's manual. Most transmission manufacturers recommend that the oil and oil filter be changed every 25,000 miles or 12 months, whichever occurs first. The transmission governor filter should be changed at the same time. Most auxiliary filters should be changed after the first 5,000 miles and thereafter at normal oil change intervals. Transmission oil may require change sooner than recommended depending on operating conditions. Oil must be changed whenever there is evidence of dirt or a high temperature condition indicated by discoloration, strong odor or oil analysis. Local conditions, severity of operation or duty cycle may dictate more or less frequent service intervals. At each oil change, examine the oil that is drained for evidence of dirt or water. A normal amount of condensation will emulsify in the oil during operation. However, if there is evidence of water, check the cooler (heat exchanger) for leakage between the water and oil areas. Oil in the water side of the cooler is another sign of leakage. If engine coolant leaks into the transmission oil system, immediate action must be taken to prevent malfunction and serious damage. The transmission must be completely disassembled, inspected and cleaned. All traces of the coolant and varnish deposits resulting from coolant contamination must be removed. Inspect the fluids closely
Metal particles in the oil or on the magnetic drain plug (except for the minute particles normally trapped in the oil filter) indicate transmission damage. When these particles are found in the sump, the transmission must be disassembled and closely inspected to find the source. Metal contamination will require complete disassembly of the transmission and cleaning of all internal and external circuits, cooler and all other areas where the particles could lodge. The transmission breather is located at the top of the transmission housing and serves to prevent pressure buildup within the transmission. The breather must be kept clean and the passage open. The presence of dust and dirt will determine the frequency at which the breather requires cleaning. Training is worthy investment
One area that is often overlooked in the industry is providing adequate training for technicians, who must stay abreast of new transmission technology. Most automatic transmission suppliers offer excellent training, and some will even provide on-site instruction. Training your technicians is certainly money well spent. It will teach your employees to properly diagnose a problem instead of guessing or changing parts until the problem is fixed. David M. Sluder is a transportation consultant for the North Carolina Department of Public Instruction.

Related Topics: preventive maintenance, transmissions

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