4. PREVENTIVE MAINTENANCE SERVICES
a. General
The fluid coupling and torque converter are assemblies which cannot be disassembled in the field. Therefore, there is little in the way of service that can be given.
b. Lubrication
The importance of proper lubrication cannot be over emphasized, since it is the most essential single factor that will determine the life of the units.
(1) Always refer to lubrication order pertaining to the piece of equipment begin serviced.
(2) When ever oil is changed in the fluid coupling or torque converter, the oil filter should be replaced and the screen cleaned before new oil is added.
NOTE : NEVER FLUSH THE FLUID COUPLING OR TORQUE CONVERTER.
(3) Before changing oil in the fluid coupling or torque converter, the oil temperature should be at the operating range. If the piece of equipment begin serviced is not equipped with an oil temperature gage, start the engine and let it run until the engine temperature gage has risen to the operating range.
5. TROUBLESHOOTING
a. General
The ability to diagnose troubles in the fluid coupling or torque converter requires a knowledge of the construction and operation of these units. Also, it requires a knowledge of what to check for, what troubles may occur, and what effects these troubles will cause.
b. Overheating
Should the fluid coupling or torque converter, become overheated, a high temperature reading on the temperature gage will result, and a hot oily smell may be emitted. Overheating may be caused by loss of oil, failure of the oil to circulate, failure of the oil cooler to function, or overload. Loss of oil could result from a leaky oil seal or even from a relief valve that is stuck open, this condition permits the oil to flow directly from the oil pump back to the reservoir without entering the coupling or torque converter. The lack of sufficient oil will cause the units to overheat. If the oil cooler is clogged with dirt, or if the coolant is low, the engine oil temperature will be high. Operating in the wrong speed range will overwork the coupling or torque converter causing excessive heat.
c. Slipping
It is not always easy to detect a slipping fluid coupling or torque converter without certain tests. They both naturally slip to a certain extent; this slippage varies with the terrain in which the equipment operates, the driving conditions, and the temperature. An accurate test for slippage can be made by using an engine RPM indicator (tachometer0. To do this, measure the engine speed and then with the service and parking brake applied accelerate the engine with transmission in high. If engine accelerates rapidly without lugging, a serious slippage is occurring, and the oil level should be checked.
Fluid couplings and torque converters can be mounted to a transmission in a housing or can be made integral by itself. If mounted together with a transmission, some of the troubles may be diagnosed as part of the transmission and therefore are much harder to detect.