1984 Chevrolet Silverado Couple quick questions about transmission

RALPHIENACHO

MEMBER
1984 CHEVROLET SILVERADO
7.4L
V8
RWD
AUTOMATIC

I have a 1984 chevy silverado pick up truck. It has a 454 engine.
It is a Turbo 400 Transmission.
if there is no power going to the kick down solenoid, could that keep the truck from shifting into 3rd gear?
and also, in the valve body of the transmission, what causes the manual valve go back into park position, when the gear selector is moved into park?
any/all help is appreciated. Thank you

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,700 POSTS

A turbo 400 is vacuum actuated and shifts based on hydraulic pressure. You should have a vacuum modulator on the side of the transmission. Is that correct?

As far as the internals of the trans, there is a parking paw that is engaged when you shift to park which locks the transmission. It is done by internal linkages.

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Tuesday, September 8th, 2015 AT 7:07 PM

RALPHIENACHO

MEMBER
2 POSTS

Yes there is a vacuum modulator on the side of the transmission.
At first the problem was that it would not shift into 3rd gear anymore.
So they pulled the valve body off, and checked it. Of course when they took it off all the check balls fell out and they had no clue where they went. Looked on internet for right locations, and not even sure they got those right. Then they put it back together, and now
All the gears seem to be all forward now. If I shift to neutral, it goes forward, if I put it in reverse, it goes forward.

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Wednesday, September 9th, 2015 AT 11:55 PM

JACOBANDNICKOLAS

MECHANIC
109,700 POSTS

The valve body was put together incorrectly. Why did they take the valve body apart? Did they do anything other to the transmission?

I attached an exploded view of the valve body to hopefully help.

Image (Click to make bigger)