700R-4 Shift Problems

[datsunatx]

I just purchased a 1984 chevy pickup with 305 and auto trans. The truck starts out from a stop in 1st then shifts into 2nd normaly but at 25mph shifts back into 1st. I have already replaced the pan gasket and filter and checked the plastic governer drive gear and it is fine, what am i missing?. I really dont want to take it to a shop, so any pros on the 700r-4 please chime in thanks.

[357mag]

Check your throttle valve cable for proper sdjustment. It looks like a kickdown cable but it's much more important. It controls line pressure inside the trans, and if not adjusted right, your trans will slowly fade away. Chilton's should have the adjustment procedure.

Tim sends

[datsunatx]

Thanks Ill try that, Anymore suggestions are welcomed

[Brian1]

Could be a vacuum tube leaking or is not connected. Haven't been around a 700r4 for many years but the Company truck I drove for 5 years with a 700 in it would occasionally have the vacuum line come off. I usually would cut off about 1/2 inch and plug it back on. I could here the leaky line under the truck when running.