I have an old 977h lever steer. The transmission seems to get weak after a cpl hours. It starts to heat ,and oil level goes up. If I let it idle and cool it goes back to normal. In the manual it refers to a bypass valve in the filter . I checked it and the spring seemed very weak ,the plunger a bit scored. It said if not working properly it can divert pressure away from the torque converter or away from clutches. Does anyone know more about this?
Check your pressures first sounds like a weak torque convertor. the bi pass valve only bipasses the filter if the filter becomes clogged
Gauge reads normal until it gets to the hot side. But its an old gauge.