86 F-250 Automatic Transmission
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86 F-250 Automatic Transmission
Auto Trans not shifting smoothly -- during acceleration stays in lower gear longer before shifting, when it does you feel a definite surge, same slowing down it shifts abruptly. I have checked fluid and replaced all the transmission fluid, no change. Truck has 237,000mi with a 6.9l Diesel/4x4. Any ideas??
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Joined: Jan 2001
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From: Virginia
How are the brakes? If you have a hard pedal, then your vacuum pump may be going out. If you have plenty of vacuum from the pump, then look up at the center of the engine where the injection pump and the throttle cable meet. There is a vacuum gizmo there that varies the vacuum according to throttle position. Check all the lines there, and follow the line all the way down to the passenger side rear of the tranny where it goes to the vacuum modulator. If there are any cracks or holes in the lines, it will cause it to shift late and hard.
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