Can anyone tell me how the vacuum is used on the Automatic Trany?
What are some of the common problems which faulty vacuum lines can cause?
My '91 EB 4x4 Automatic trany is making a loud vibration (perhaps 20 Hz) noise when it tries to downshift under a slow, gentle load. Once it does downshift, the noise stops. I suspect a vacuum problem, but it could be something else.
Thanks in advance,
Mike
The vacuum line is attached to the modulator valve. Essentially, it tells the transmission what kind of load the motor is under. High vacuum (as in low throttle opening/light load or coast down) would cause a drop in transmission line pressure while low vacuum ( a sign that the engine is under a heavy load) will increase transmission main line pressure.
-- Jim Warman snipped-for-privacy@telusplanet.net
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