Twin Disc TA-90-8501, Operator'S Manual

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Twin Disc, Incorporated
Troubleshooting
Power Transmission System Operator’s Manual #1020510
Poor Engine Flywheel Scavenge
Another possibility is that the engine flywheel housing is running with too
much residual oil. The lube oil and normal leakage from the torque
converter must be removed (scavenged) from the flywheel housing and
returned to the transmission sump. This is done with the scavenge pump
mounted on the torque converter. If the oil is not completely scavenged
from the flywheel housing, the excess oil will cause drag on the engine.
This will create both heat and loss of power.
Poor flywheel housing scavenging can be detected by looking for heat
discolored paint on the torque converter housing or on the transmission
at the scavenge oil return port area. Or, after running the engine at low
idle for a few minutes, shut the engine off and feel the transmission
housing in the area of the scavenge oil return port. If this area is much
hotter than the other areas of the transmission, the scavenge return
system is not working properly.
Inspect and clean the strainer screen at the inlet side of the scavenge
pump.
Disconnect the hose at the outlet side of the scavenge pump and direct
it to a bucket. Start the engine and observe if oil is coming from the
pump. Initially the hose should run full until the oil from the flywheel housing
is evacuated. While the hose is running full, catch the oil in a 2 liter or ½
gallon container and measure the time to fill the container. At 700 RPM,
the pump should deliver 21.3 liter/minute (5.6Gal/minute) or fill the
container in about 5 to 6 seconds. When the flywheel housing is
evacuated, the hose should flow a mixture of air and oil. If the pump
outlet is below the expected value, check for damaged or loose hose or
fittings in the suction side of the scavenge pump. Also, check the drain
port at the bottom of the engine flywheel housing for obstructions.
Replace the scavenge pump if necessary.
Failed Converter
If the pump continues to deliver a solid stream of oil and the pump is
delivering as expected , it is likely that the leakage from the torque
converter is greater than normal and the scavenge pump can not keep
up. The torque converter must be removed for repair. Raise engine rpm
to approximately 1000 rpm and run for several minutes. Repeat the oil
flow measurement at this engine rpm. A solid oil stream at this rpm
supports the decision to remove the torque converter because of
excessive leakage.