Transmission not shifting properly

1984 CHEVROLET TRUCK
150,000 MILES • V8 • 2WD • AUTOMATIC
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TOMBOYWV
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After pulling out and getting my truck to shift through all the gears as soon as I let off the gas it shifts down. When I put it into neutral and back in drive it works until I let off of the gas again then it shifts down into second again and will not shift back up until I put it into neutral again.
Dec 14, 2017 at 6:26 PM
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STRAILER
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Hello,

It sounds like you have a vacuum leak to the modulator. There is a vacuum line that runs from the engine intake manifold to the valve. Here is a diagram that will show you the location. Check the hose for leaks and sometimes it just falls off #22.

Check out the diagrams (below).

Please let us know what you find. We are interested to see what it is.

Cheers, Ken
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Dec 16, 2017 at 11:30 AM
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TOMBOYWV
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I have changed the vacuum modulator, and the tv cable. Checked the vacuum line that runs all the way up to the intake manifold. Nothing has helped. Do you have any more suggestions
Dec 18, 2017 at 6:39 PM
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TOMBOYWV
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Now when I let off of the gas it acts like it goes into neutral instead of shifting down into 2nd
Dec 18, 2017 at 6:42 PM
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STRAILER
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It sounds like you have an internal issue such as a broken sprag or planetary gear. It might be time for a rebuild.

Please let us know what happens.

Cheers, Ken
Dec 19, 2017 at 12:57 PM